Unity 2 User Manual - Orsatorsat.com/pdfs/MARKESSYSTEM_QUI1057UserManual.pdf · Markes...

Markes International Ltd

T: +44 (0)1443 230935 F: +44 (0)1443 231531 E: [email protected]

www.markes.com

QUI-1057

Version 2.0 – February 2014

User manual

UNITY 2™

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Contents

1. Preface ................................................................................................. 5

1.1 Notices ............................................................................................ 5

1.2 Warranty .......................................................................................... 5

1.3 Regulatory compliance .................................................................. 5

1.4 Important safety warnings ............................................................. 5

1.4.1 Labels/symbols ................................................................. 6

1.4.2 Mains voltages .................................................................. 6

1.4.3 High temperatures ............................................................ 6

1.4.4 Hydrogen gas safety ......................................................... 7

1.4.5 Cleaning and decontamination ........................................ 7

1.5 Environment operating conditions ................................................ 7

1.5.1 Temperature ...................................................................... 7

1.5.2 Humidity ............................................................................ 7

1.5.3 Altitude .............................................................................. 8

1.6 Technical Specifications ................................................................ 8

1.6.1 Physical properties ........................................................... 8

1.6.2 Electrical properties .......................................................... 8

1.7 Technical support contact details ................................................. 8

2. Instrument familiarisation .................................................................. 9

2.1 Hardware ........................................................................................ 10

2.1.1 Sample tubes .................................................................... 10

2.1.2 Tube desorption oven ....................................................... 10

2.1.3 Tube filters and seals ....................................................... 10

2.1.4 The cold trap ..................................................................... 10

2.1.5 Cold trap cooling and heating .......................................... 10

2.1.6 Trap filters and seals ........................................................ 11

2.1.7 Split filters ......................................................................... 11

2.2 Sequence of operation ................................................................... 12

2.2.1 Standby .............................................................................. 12

2.2.2 Leak test ............................................................................ 13

2.2.3 Prepurge ............................................................................ 14

2.2.4 Primary (tube) desorption ................................................ 15

2.2.5 Pre trap fire purge ............................................................. 16

2.2.6 Secondary (trap) desorption ............................................ 17

2.3 Insertion and removal of a sample tube in UNITY 2 .................... 18

2.3.1 Insertion............................................................................. 18

2.3.2 Removal ............................................................................. 18

2.4 Desorb and split flows .................................................................... 18

2.4.1 Gas flow through the cold trap ........................................ 18

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2.4.2 When should desorb/split flows be measured? ............. 18

2.4.3 The Set Gas Flow function................................................ 19

2.4.4 Measuring and adjusting flows during Set Gas Flow ..... 19

2.4.5 To exit the Set Gas Flows Function .................................. 20

2.4.6 Gas flow constraints - minimum & maximum settings .. 20

2.4.7 Sample splitting ................................................................ 20

2.4.8 Analytical column capacity ............................................... 20

2.4.9 GC system detection limits ............................................... 20

2.4.10 Calculating analyte masses in the sample tube ............. 21

2.4.11 Calculating splits/split modes ......................................... 21

2.4.12 UNITY 2 systems with Electronic Carrier Control (ECC) .. 22

2.4.13 UNITY 2 systems configured with Electronic Mass

Flow Control....................................................................... 22

3. Software ............................................................................................... 23

3.1 Running the software ..................................................................... 23

3.2 Status bar ....................................................................................... 23

3.2.1 External ready signal ........................................................ 24

3.3 Toolbar functions ............................................................................ 25

3.3.1 Method Linking ................................................................. 27

3.3.2 The Trap Heat Method ...................................................... 29

3.3.3 Schematic display of UNITY 2 status ............................... 30

3.3.4 Controlling method ........................................................... 30

3.4 UNITY 2 Options.............................................................................. 30

3.4.1 Configuration ..................................................................... 31

3.4.2 GC Interface ...................................................................... 32

3.4.3 Gas & Flow ........................................................................ 32

3.4.4 Methods ............................................................................. 33

3.4.5 Reporting ........................................................................... 35

3.5 UNITY 2 method options ................................................................ 36

3.5.1 Split on or off in standby .................................................. 36

3.5.2 The Leak Test .................................................................... 36

3.5.3 Determining the prepurge time ....................................... 36

3.6 Desorption modes .......................................................................... 37

3.6.1 Tube conditioning mode ................................................... 37

3.6.2 Standard 2(3) stage desorption ...................................... 38

3.6.3 Sample tube prepurge ...................................................... 42

3.6.4 Sample tube prepurge at elevated temperature ............ 43

3.6.5 SecureTD-Q™ - Re-collection for repeat analysis ........... 43

3.6.6 Cold Trap conditioning ...................................................... 44

3.6.7 UNITY 2 parameter specifications ................................... 45

3.7 Uninstalling UNITY 2 software ....................................................... 46

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3.7.1 Windows 7 ......................................................................... 46

3.7.2 Windows Vista ................................................................... 47

3.7.3 Windows XP ....................................................................... 47

4. Accessing product and support information ...................................... 48

4.1 Markes International Limited - Home Page and facilities............ 48

4.2 Consumables and Spares .............................................................. 48

4.3 Applications library ......................................................................... 48

4.4 Technical support ........................................................................... 48

5. Technical Support ................................................................................ 49

5.1 Routine maintenance schedule .................................................... 49

5.2 Sorbent Tubes ................................................................................ 49

5.2.1 Packing tubes .................................................................... 49

5.2.2 Lifespan of tubes .............................................................. 50

5.2.3 Conditioning tubes ............................................................ 51

5.2.4 Long term storage of clean and sampled tubes ............. 52

5.2.5 Changing tube seals and filters ....................................... 52

5.2.6 Changing the charcoal split tube filters .......................... 53

5.2.7 Changing DiffLok cap o-rings (UltrA) ............................... 53

5.3 Cold Trap ......................................................................................... 55

5.3.1 Packing / conditioning a cold trap................................... 55

5.3.2 Removing / replacing a cold trap .................................... 56

5.3.3 Removing / replacing a broken cold trap ....................... 61

6. Trademarks .......................................................................................... 67

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1. Preface

This manual provides detailed instructions on the use of the UNITY 2. It is suitable for users with little or

no prior experience of the system and details the software/hardware interface and procedure for first

sample runs.

1.1 Notices

No part of this manual may be reproduced in any form or by any means (including electronic storage and

retrieval or translation into a foreign language) without prior agreement and written consent from Markes

International.

Please note that the material contained in this document is subject to being changed, without notice, in

future editions. Markes International shall not be liable for errors or for incidental or consequential

damages in connection with the supply, use or performance of this document or of any information

contained herein, unless a separate agreement between Markes International and the user should take

precedence.

1.2 Warranty

UNITY 2 is designed for laboratory use only. It is not intended for use in domestic establishments or

establishments directly connected to a low-voltage power supply network that supplies buildings used for

domestic purposes. Where equipment is used in a field placement environment, care must be taken to

ensure that the instrument is not exposed to detrimental conditions, i.e. rain, wind, or sun. Exposure may

diminish the performance, cause damage to the instrument and/or cause the equipment to become

unsafe to the user.

If the equipment is not used in a way specified by Markes International, the safety protection provided by

the equipment may be reduced. Furthermore, system failures arising from such use may not be covered in

standard warranty and/or service contract agreements.

1.3 Regulatory compliance

The instrument is designed and manufactured under a quality system registered to ISO 9001.

The instrument conforms to the following standards:

International Electrochemical Commision (IEC):

o 61010-1:2001.

o 61010-2-010:2003.

o 61010-2-081:2001.

CAN/CSA C22.2 No. 61010-1 and UL 61010-1.

The instrument conforms to the following regulation on electromagnetic compatibility (EMC):

o IEC/EN 61326-1:2006.

1.4 Important safety warnings

There are several important safety notices to keep in mind when installing and using this instrument.



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1.4.1 Labels/symbols

Throughout this manual symbols will appear where carrying out an operation may involve hazards.

Symbols and warnings also appear on the instrument, and these should be adhered to

Markes International can accept no liability for failure to do so.

BURN HAZARD

A hot surface may result in a burn injury.

INSTRUMENT/PART DAMAGE

Damage to the instrument or module may occur. This damage may not be covered under

the standard warranties.

LIFTING HAZARD

Injury may occur if proper lifting procedures are not followed.

WARNING

General warning symbol to alert the user that personal injury or instrument damage may

occur if the instrument is improperly used or if instru

DISPOSAL

This label indicates the instrument must not be disposed in regular waste but in

accordance with the WEEE scheme

1.4.2 Mains voltages

Ensure at all times that the plug (electrical isolator) can be easily and

accessed during equipment use.

The instrument must be suitably earthed via the power cord.

NOTE: Voltages within the instrument will be a maximum of 24 V. Although there is

decreased risk of serious injury, these internal voltages should still be

as dangerous. Contact with any live parts may cause personal injury and/or

instrument damage.

1.4.3 High temperatures

Several parts of the UNITY 2

these zones whilst the system is in operation

zones are:

o Heated valve.

o Tube oven.

See Section 2 for the location of these zones. Both these zones are labelled with

‘Burn hazard’ labels similar to that shown above.

ALWAYS operate the instrument with the covers in pl

with these zones.

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Symbols and warnings also appear on the instrument, and these should be adhered to

Markes International can accept no liability for failure to do so.

A hot surface may result in a burn injury.

INSTRUMENT/PART DAMAGE


standard warranties.

Injury may occur if proper lifting procedures are not followed.

symbol to alert the user that personal injury or instrument damage may

occur if the instrument is improperly used or if instructions are not followed correctly.


accordance with the WEEE scheme.

Ensure at all times that the plug (electrical isolator) can be easily and

accessed during equipment use.

The instrument must be suitably earthed via the power cord.

: Voltages within the instrument will be a maximum of 24 V. Although there is

decreased risk of serious injury, these internal voltages should still be


instrument damage.

Several parts of the UNITY 2 can be operated at high temperatures

these zones whilst the system is in operation can cause serious burn injury. These


‘Burn hazard’ labels similar to that shown above.

ALWAYS operate the instrument with the covers in place to avoid accidental contact

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Symbols and warnings also appear on the instrument, and these should be adhered to at all times.


symbol to alert the user that personal injury or instrument damage may

ctions are not followed correctly.


Ensure at all times that the plug (electrical isolator) can be easily and quickly

: Voltages within the instrument will be a maximum of 24 V. Although there is

decreased risk of serious injury, these internal voltages should still be treated


high temperatures. Contact with

can cause serious burn injury. These


ace to avoid accidental contact

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Due to the high temperatures involved in the flow path, other zones of the instrument

will be at higher temperatures during operation. These may not on visual inspection

be obvious to the user. These zones are:

o The insulation of the GC transfer line.

o Top and side covers (especially directly above the heated valve).

See Section 2 for the location of these zones.

1.4.4 Hydrogen gas safety

Hydrogen is a colourless, odourless, highly flammable gas. Hydrogen presents a

hazard as it is combustible over a variety of concentrations at ambient temperature

and pressure. It has a low ignition temperature and is very fast-burning.

If the user does use hydrogen as their carrier gas, then they do so at their own risk.

The user must ensure that all adequate safety precautions are taken and that the

installation of the hydrogen system is carried out in accordance with all applicable

codes and standards.

Markes International will assume no liability for any damage or injury caused by the

use of hydrogen.

For further advice on the use of hydrogen as a carrier gas, please contact Markes

International Technical Support.

1.4.5 Cleaning and decontamination

Please consult Markes International or your local agent for information on decontamination or the use of

cleaning agents

NOTE: Incorrect cleaning/decontamination could result in damage to the instrument.

1.5 Environment operating conditions

The instrument should be protected from conditions that could cause exposure to frost, dew, percolating

water, rain, excessive direct sunlight, etc.

Performance can be affected by sources of heat and cold from heating, air conditioning systems, or drafts.

It is advisable to operate the system in a clean laboratory environment, with minimal atmospheric

concentrations of organic vapours.

1.5.1 Temperature

Recommended operating ambient temperature range is 15 to 30°C.

1.5.2 Humidity

Recommended operating humidity range is 5 to 95% non-condensing.

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1.5.3 Altitude

The product has been evaluated for operation up to a maximum of 6500 ft (2000 m), in accordance with

safety standards. Higher altitudes pose no safety risk, but instrument performance may be reduced.

NOTE: For storage or shipping the allowable temperature range is -40 to 70°C and the allowable humidity

range is 5-95% non-condensing. After instrument exposure to extremes of temperature or

humidity, allow 2 hours for return to the recommended ranges before switching on.

1.6 Technical Specifications

1.6.1 Physical properties

Height: 40 cm (15.75”)

Width: 16 cm (6.3”)

Length: 51 cm (20”)

Mass: 16 kg (35.2 lbs)

1.6.2 Electrical properties

Maximum Power: 650 W

Line voltage: 100-240 V (automatically selected)

Frequency: 50/60 Hz

Input inrush current (A): <40 A (cold start)

1.7 Technical support contact details

In the first instance please contact your distributor. If they are unable to resolve your query, please contact

Markes International (details below).

Address: Gwaun Elai Medi-Science Campus, Llantrisant, RCT, UK, CF72 8XL

Website: www.markes.com

E-Mail: [email protected]

Telephone: +44 (0)1443 230935

Fax: +44 (0)1443 231531

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2. Instrument familiarisation

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2.1 Hardware

2.1.1 Sample tubes

UNITY 2 is compatible with industry standard sample tubes - 3.5 inches (89 mm) long by ¼-inch (6.4 mm)

O.D with 5 mm (stainless steel and coated steel) or 4 mm (glass) I.D. Sorbent is retained in stainless steel

(or coated steel) tubes using stainless steel (or coated steel) gauzes and a gauze retaining spring. Quartz

or glass wool is recommended for retaining the sorbent in glass tubes.

2.1.2 Tube desorption oven

The UNITY 2 tube desorption oven heats up rapidly (~150°C/min) at the start of elevated temperature

purge (see Section 3.6.4) or tube desorption. It begins to cool at the end of primary (tube) desorption and

reaches 50°C from 300°C within 10 minutes.

2.1.3 Tube filters and seals

When ready for analysis, sample tubes are placed into the ambient temperature desorption oven with the

sampling (grooved) end pointing to the rear of the instrument. Operation of the lever mechanism seals

the sample tube into the UNITY 2 flow path. Temperature resistant Viton O-rings seal onto the outer wall

of the sample tube, ~2 mm from either end. Each O-ring should last for >1000 tube-sealing operations. In

the event of failure, O-rings at both ends of the sample tube are readily replaced by the user (see

Technical Support Manual). A porous PTFE filter sits just behind the O-ring in both sample tube seals.

These prevent UNITY 2 flow path contamination in the event that sorbent particles or high boiling sample

materials migrate out of the tube. The filters are readily accessed for user replacement (See Technical

Support Manual).

2.1.4 The cold trap

The quartz cold trap contains a 2 mm diameter x 60 mm long bed of sorbent (30 to 100 mg depending on

sorbent density) supported by quartz or glass wool. Note that the length of the first plug of glass wool is

included in the total 60 mm sorbent bed.

2.1.5 Cold trap cooling and heating

UNITY 2 contains a 2-stage Peltier cell, which uniformly cools the entire 60 mm sorbent bed to a minimum

of -30°C in ambient temperatures as high as +25°C (see UNITY 2 Installation Manual Section 1). No

liquid cryogen is required. Dry air or nitrogen flows into the cold trap box creating a slight positive pressure

and minimising ingress of water from the laboratory atmosphere. If the cold trap box was not purged, ice

would quickly build up around the Peltier cell which is maintained at sub zero temperatures throughout

UNITY 2 operation.

NOTE: C2 hydrocarbons (ethyne, ethene, ethane) and the most volatile freons cannot normally be

sampled using sorbent tubes at ambient temperatures - breakthrough volumes are too small for practical

use, even with the strongest tube sorbents. These compounds must be collected in bags or canisters or

sampled on line. These whole air/gas samples are then introduced to the UNITY 2 cold trap using an Air

Server Accessory.

Once all the target analytes have been collected and focused in the cold trap, the trap oven heats rapidly

reaching rates in excess of 60°C/sec for the first critical stages of trap desorption. Uncompromised

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capillary chromatography is produced without on-column focusing and with desorption flows as low as 2

ml/min. This facilitates splitless operation with high-resolution capillary GC.

2.1.6 Trap filters and seals

As with the sample tube, the cold trap is sealed into the gas flow path of UNITY 2 via O-rings, which seal on

the outer wall of the trap tube. At the cool non-valve end of the trap, the O-ring is backed up with a porous

PTFE filter to prevent contamination of the pneumatics in the event of sorbent particles migrating out of

the trap. The user has access to this O-ring seal and filter in the connector (see Technical Support

Manual), but a Service visit is required to access and change the trap O-ring seal in the heated valve. As

the cold trap is only changed infrequently, the seals will rarely, if ever, need to be replaced. It is

recommended that UNITY 2 is professionally serviced once per year and that the valve-end seal be

changed as part of this annual maintenance operation.

2.1.7 Split filters

There is a split filter tube packed with charcoal (SERUTD-5065) on the split line upstream of the on/off

solenoid and needle valves. This prevents the split portion of the sample from contaminating the valves

and from reaching the laboratory air. The flow path up to the charcoal filter is heated and constructed of

inert-coated, stainless steel tubing. The split filter itself is the same size as a standard sample tube and

may be readily replaced by a clean sorbent tube if the split effluent is to be re-collected for repeat

analysis, see Section 3.6.5. The split filter (or re-collection tube) is sealed into the split flow line using

easy-connect, Viton O-ring seals and by operating a lever in the same manner as the sample tube. The

sampling end/grooved end of the re-collection tube should point to the rear of the instrument.

Conventional charcoal split filters will become contaminated over time and should be reconditioned or

repacked when required.

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2.2 Sequence of operation

When a tube is placed and sealed into the flow path of UNITY 2 for conventional 2(3) stage desorption, it

undergoes the following sequence of operations: standby, leak test, prepurge, primary desorption, pre trap

fire purge and secondary desorption.

2.2.1 Standby

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

STANDBY

Pressure and flow

Pressure (flow optional)

Pressure, no flow

KEY

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2.2.2 Leak test

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

Pressure and flow


Pressure, no flow

KEY

From the Standby position the UNITY 2 Status changes to Leak test. The system allows carrier gas through

the tube and into the cold trap and split filter and the whole sample flow path is pressurised to capillary

column head pressure. Carrier gas continues to be supplied to the capillary analytical column throughout

the leak test (as it is through every other stage of UNITY 2 operation).

After 5 seconds the flow path is isolated from the capillary column head pressure and a pressure

transducer monitors the pressure in the sample flow path. If the measured pressure drops by more than

5% in 30 seconds this is classified as a leak in the sample flow path and UNITY 2 status changes to Tube

Leaked.

If the system maintains pressure, no leak is detected and UNITY 2 passes on to the second part of the

leak test. The flow path is depressurised briefly. The sample flow path pressure is again monitored to see

if it increases by 5% over 30 seconds. This would indicate an internal leak across the heated valve. If

UNITY 2 fails this part of the leak test, the status again changes to Tube Leaked. Failure of this part of the

leak test requires the attention of a trained service engineer.

The main causes of Leak Test Failure are:

Wearing of the O-rings which seal the tube

Interference with the tube seal by fibres and particles

Damaged O-rings

Leaking split filter tube seal

Wearing of the cold trap seals

See the Technical Support Manual for further information.

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2.2.3 Prepurge

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

Pressure and flow


Pressure, no flow

KEY

Each tube must be purged thoroughly with carrier gas to remove air before heat is applied. Even the

smallest trace of oxygen could result in sorbent and possible analyte oxidation, generating artifacts and

compromising data quality.

There is also the option in this step to perform an elevated temperature purge. See Section 3.6.4.

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2.2.4 Primary (tube) desorption

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

Pressure and flow


Pressure, no flow

KEY

At the start of primary (tube) desorption the tube oven begins to heat (either from ambient or from the

temperature of the optional elevated temperature purge if selected). Note that the tube desorption time is

measured from the beginning of tube oven heating and not from the time at which the sample tube

reaches the desorption temperature.

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2.2.5 Pre trap fire purge

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

Pressure and flow


Pressure, no flow

KEY

Following primary desorption, the heated valve is moved and carrier gas is flushed through the split tube

and the trap to remove any residual air and water prior to trap injection. It may also be used to dry purge

the cold trap prior to injection when direct desorbing solid or humid samples.

This pre-trap fire purge time can be adjusted in the TD method.

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2.2.6 Secondary (trap) desorption

Sam

ple

Tube

Split

Tube

Cold

Tra

p

GC

Heated Valve

Pressure and flow


Pressure, no flow

KEY

The final stage is secondary trap desorption. The cold trap is heated at a rate of 100°C/s during the first

seconds ensuring rapid desorption of analytes into the carrier gas stream. The flow through the cold trap

at this stage is determined by the column flow and any outlet split.

NOTE: the flow path of UNITY 2 remains in the trap desorption configuration until the trap has cooled

below 50°C.

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2.3 Insertion and removal of a sample tube in UNITY 2

2.3.1 Insertion

Tubes are inserted using the left-hand lever mechanism. Orientate the tube such that the sampling

(grooved) end is pointing to the rear of the instrument. Before inserting a sample ensure that the tube

oven is relatively cool, note that the oven temperature is displayed on the UNITY 2 software status bar

(see section 3.2). Place the tube horizontally in the tube oven, such that it is clear of the seals at both

ends. Operate the lever towards the rear of the instrument to seal the tube into the UNITY 2 flow path.

The instrument is then ready to run.

2.3.2 Removal

As soon as a tube has been desorbed (i.e. after primary desorption) it can be removed from the desorption

oven. If the oven and tube are still hot (you can check this by looking at the software status bar, it is

strongly recommended that the tube extractor tool, included in the shipping kit, is used to remove the

tube. Use the tool to grasp the tube at the end released from the tube seal and pull steadily.

2.4 Desorb and split flows

2.4.1 Gas flow through the cold trap

The UNITY 2 cold trap operates in backflush mode - the sample gas stream enters and leaves the cold trap

through the narrow-bore/restricted end which points to the rear of the instrument. Backflush desorption

allows use of a series of 2 or 3 sorbents of increasing strength in the cold trap. This facilitates the

analysis of wide volatility range samples (High boiling compounds are retained by and quantitatively

desorbed from the first weak sorbent, without ever coming into contact with the stronger sorbents behind).

2.4.2 When should desorb/split flows be measured?

Whenever a needle valve adjustment knob has been moved (deliberately or accidentally).

Whenever the GC column has been changed.

Whenever the carrier gas pressure to UNITY 2 has been changed.

Measuring the flows is often done at the start of a sequence of analyses to confirm/ensure that no

system changes have taken place.



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2.4.3 The Set Gas Flow function

The Set Gas Flow function is accessed by selecting Instrument and then Set Gas Flow from the drop down

menu. Alternatively, click on the Set Gas Flows icon

On selecting Set Gas Flows a dialogue box is displayed.

If the analysis method is to include a split (single or double) then answer ‘Yes’ to the question in the box.

The UNITY 2 flow path will then alter to allow both the desorb flow and the split flow to

measured at the split and desorb flow vents.

If the analysis method is completely splitless or if only the desorb flow needs to be set, then answer ‘No’ to

the question in the box. The UNITY 2 flow path will then alter so that there is no

flow, to be adjusted and measured.

2.4.4 Measuring and adjusting flows during Set Gas Flow

A flow meter is used to measure the gas flows on UNITY 2 (non Electronic Carrier Control, ECC). A simple

bubble flow meter will suffice, however a digital one is more convenient and is available from Markes

International Ltd. (C-FLMTR).

NOTE: When UNITY 2 is setup with ECC, the flow can be read from the GC. However it can be useful to

confirm the flow readings with a flow meter. See Electronic

further information.

Most applications will require a flow meter with a minimum working range of 1 and 100 ml/min.

If a manual bubble flow meter is being used, then a stopwatch will also be required. It only m

to adjust and measure flows for the current controlling method.

To measure the flow, push the flow meter tubing over the relevant copper outlet pipe. Flows are adjusted

by turning the adjustment knob clockwise to close the needle valve and redu

to open and increase the flow.

NOTE: The flows measured using Set Gas Flows are approximate. Approximate flows and split ratios are

sufficient for most methods, as there will be minimal run to run flow/split ratio variability

to know absolute flow rates for some reason, re

before the start of sample analysis. Measure the desorb and split flow (if applicable) during tube

desorption and the split flow again (if applicable) during trap desorption. The split flow may be slightly

lower during trap desorption than during tube desorption because of the relatively higher impedance of

the narrow cold trap tube.

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menu. Alternatively, click on the Set Gas Flows icon on the toolbar.

cting Set Gas Flows a dialogue box is displayed.


The UNITY 2 flow path will then alter to allow both the desorb flow and the split flow to

measured at the split and desorb flow vents.


the question in the box. The UNITY 2 flow path will then alter so that there is no split flow, only the desorb

Measuring and adjusting flows during Set Gas Flow


er a digital one is more convenient and is available from Markes

When UNITY 2 is setup with ECC, the flow can be read from the GC. However it can be useful to

confirm the flow readings with a flow meter. See Electronic Carrier Control (ECC) Installation Manual for


If a manual bubble flow meter is being used, then a stopwatch will also be required. It only m

to adjust and measure flows for the current controlling method.


by turning the adjustment knob clockwise to close the needle valve and reduce the flow and anticlockwise

The flows measured using Set Gas Flows are approximate. Approximate flows and split ratios are

sufficient for most methods, as there will be minimal run to run flow/split ratio variability

to know absolute flow rates for some reason, re-measure the actual flows by desorbing a blank tube


(if applicable) during trap desorption. The split flow may be slightly


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The UNITY 2 flow path will then alter to allow both the desorb flow and the split flow to be adjusted and


split flow, only the desorb


er a digital one is more convenient and is available from Markes

When UNITY 2 is setup with ECC, the flow can be read from the GC. However it can be useful to

Carrier Control (ECC) Installation Manual for


If a manual bubble flow meter is being used, then a stopwatch will also be required. It only makes sense


ce the flow and anticlockwise

The flows measured using Set Gas Flows are approximate. Approximate flows and split ratios are

sufficient for most methods, as there will be minimal run to run flow/split ratio variability. If it is necessary

measure the actual flows by desorbing a blank tube


(if applicable) during trap desorption. The split flow may be slightly


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The column flow should be measured at the detector end using procedures recommended for the GC in

question. Once adjusted and measured as required, all the flows can be entered into the Confirm/Enter

Flows dialog box on the controlling method, see Section 3.6.2.

2.4.5 To exit the Set Gas Flows Function

After the measurement of gas flows is complete the user must press the Stop sequence icon to exit

the Set Gas Flows function and return UNITY 2 to Standby status.

2.4.6 Gas flow constraints - minimum & maximum settings

The system must be set up with at least 10 ml/min flow through the tube - and at least 2 ml/min desorb

flow through the cold trap during tube desorption to provide efficient desorption of the tube and efficient

transfer of analytes to the cold trap.

Use much faster flows through the hot tube (>50 ml/min) and at least 10 ml/min through the cold trap

when analysing high boilers (>n-C20).

At least 2 ml/min must be used when desorbing the trap. The total flow can be directed to the GC

analytical column or to a combination of column and split vent. The flow through the cold trap should not

normally be allowed to exceed 100 ml/min during either tube desorption or trap heat.

Some variation in flow will be observed through a needle valve if used at less than 2 ml/min.

Flow through tube during tube desorption = desorb flow + split flow (if selected)

Flow through trap during tube desorption = desorb flow

Flow through trap during trap heat = column flow + split flow (if selected)

2.4.7 Sample splitting

UNITY 2 may be set up to offer sample splitting between zero (splitless) and 10,000:1 (double split). The

split that is required for a particular analysis will be dependent on the analyte mass in the sample tube,

the analytical column capacity and the sensitivity of the GC detector selected.

2.4.8 Analytical column capacity

The capacity of an analytical column will depend on its diameter and the thickness of the film of stationary

phase. As a general rule a 0.25 mm I.D. column with a 0.25 µm film has an approximate sample capacity

of 100 ng per component. Wider bore and thicker film columns will have a higher sample capacity - up to

low micrograms in the case of thick film (5 mm), 0.53 mm I.D. columns. Narrower bore and thinner film

columns will have a lower sample capacity - below 10 ng per component in some cases.

2.4.9 GC system detection limits

The specification of GC detectors varies from type to type and manufacturer to manufacturer and it is

advisable to consult the relevant manufacturer regarding detection limits. However, the following general

guidelines may be useful:

Mass Spec., full scan mode: Modern systems should comfortably be able to detect and quantify a single

compound at 10-100 pg.

Mass Spec., single ion mode: Modern systems should comfortably be able to detect and quantify a single

compound at 1 pg.

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Flame Ionisation Detector (FID): Typical detection limits 10-100 pg for individual hydrocarbons.

Electron Capture Detector (ECD): Highly selective detector. Used for halogenated solvents. Detection

limits well below 1 pg for compounds such as carbon tetrachloride and some heavily halogenated

pesticides.

Thermal Conductivity Detector (TCD): General purpose, low sensitivity detector. Typical detection limits in

the order of 10 ng.

2.4.10 Calculating analyte masses in the sample tube

In order to determine the required split it is necessary to have an approximate idea of the mass of analyte

which is expected to be retained/collected in the sample tube.

For direct desorption of volatiles from materials, the mass of analyte is most easily determined

experimentally from control or real-life samples. It can also be calculated from relevant material

specifications where appropriate e.g. if the specification for residual chloroform in cough medicine is 1%

w/w a 20 mg sample will contain 200 µg or less of chloroform.

For air monitoring applications the calculations are a little more complex as they depend on variables such

as diffusive uptake rate, pumped volume and molecular weight (See Markes TDTS 25).

2.4.11 Calculating splits/split modes

Once the expected mass of analyte, the detection limits of the system and the analytical capacity of the

column are all known, then an overall ideal split can be calculated. For example if the expected mass of

analyte on the sample tube is 50 µg and the analytical column capacity is 100 ng then a total split of at

least 1/500 is required to prevent column overload - i.e. only 0.2% of the sample must be transferred to

the column. One of three different split modes can be utilised:

Zero split or

splitless

Unusually among thermal desorbers,

UNITY 2 can operate in splitless mode

in conjunction with narrow bore (0.32

mm ID) columns and MS detectors as

the minimum flow required through

the cold trap during trap heat is 2

ml/min.

During tube desorption the desorb flow must

be set to at least 10 ml/min to provide

enough flow through the sample tube for

efficient thermal desorption.

During tube desorption the desorb flow should

not far exceed 50 ml/min or there may be a

risk of breakthrough from the cold trap.

Single split During single split operation the split

may either be open during tube or trap

desorption. The advantages of having

the split open on the way into the trap

(inlet split) are:

1. That a relatively fast flow can be

used through the tube to

facilitate desorption while, at the

same time, the flow passing

through the cold trap is kept low

to aid retention and focusing of

analytes.

During tube desorption the desorb flow must

be set to at least 10 ml/min to provide

enough flow through the sample tube for

efficient thermal desorption.

During tube desorption the trap flow should

not exceed 50 ml/min or there may be a risk

of breakthrough from the cold trap.

During tube desorption the trap flow should

not be less than 2 ml/min to ensure efficient

sweeping of analytes onto the trap sorbent.

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2. That the cold trap is not

overloaded with solvent or

analytes. Split discrimination

and / or peak splitting may be

observed if the trap is allowed to

become overloaded with volatile

solvent or water.

Double split During double split operation the split

is open both during tube desorption

and trap heat.

As above for single split operation.

During splitless operation:

Flow through tube during tube desorption = Desorb Flow

Flow through trap during tube desorption = Desorb Flow

Flow through trap during trap heat = Column Flow

During single split operation:

Flow through tube during tube desorption = Desorb Flow + Split Flow (if selected)


Flow through trap during trap heat = Column Flow + Split Flow (if selected)

During double split operation:

Flow through tube during tube desorption = Desorb Flow + Split Flow


Flow through trap during trap heat = Column Flow + Split Flow

2.4.12 UNITY 2 systems with Electronic Carrier Control (ECC)

When installed with certain models of commercial GC(-MS), UNITY 2 systems can be configured with

electronic control of the carrier gas as it leaves the cold trap and enters the fused silica (or length of

analytical capillary column) inside the transfer line. In this case, manual adjustment of the desorb and

split flows, as described above, is still required.

Key benefits of electronic control of the carrier gas through the column include retention time stability

(even when split flows are changed significantly) and pressure programming for enhanced

chromatographic performance with higher boiling compounds.

For further information see the Electronic Carrier Control (ECC) Installation Manual.

2.4.13 UNITY 2 systems configured with Electronic Mass Flow Control

Mass Flow Control Accessories are available and offer automatic adjustment and closed loop control of

the flows during the thermal desorption cycle. For example, this means that different split flows can be set

for each of these different phases of operation. The accessories also offer electronic flow readout during

manual adjustment of the desorb flow.

For further information see the MFC Installation Manual.

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3. Software

UNITY software will run on most 32-bit versions of Windows® and 64-bit versions of Windows 7, however,

use of currently supported versions of Windows is strongly recommended. In general, a PC with sufficient

resources to run 32-bit Windows should have enough performance to control UNITY.

Other Windows software may be active on the PC at the same time as UNITY 2 software, for example data

handling software, word processing and spreadsheet functions.

3.1 Running the software

First ensure UNITY 2 is switched on then start the software as described in the UNITY 2 Installation

Manual.

If communications between the PC and UNITY 2 are established successfully the software will open.

UNITY 2 then begins to operate using the active controlling method, see Section 2.3.4. The controlling

method will contain default parameters when UNITY 2 software is first downloaded.

If for some reason, communication is not established, an ‘Instrument not Detected’ box appears with a

number of options.

Cycle Power and retry?

Run simulation?

Select options?

Exit?

Choose Select options. This will take you to the Ports tab of Options under the View menu (see Section

2.4.4.). Ensure that the correct PC comms port is selected. Change the default comms port if necessary by

clicking on the down arrow and then clicking on the correct comms port in the list. Close down UNITY 2

software, switch the power to UNITY 2 off, wait ten seconds and then switch UNITY 2 back on again. Re-

access the UNITY 2 program on the PC as described above.

3.2 Status bar

The UNITY 2 status bar displays all key UNITY 2 parameters and is always visible and on top of the

desktop while the software is open, whether maximised or minimised.

Status Elapsed

Time Pressure UNITY zones GC

The level of information presented for each category may be selected by a right click of the mouse on the

appropriate section of the status bar. The parameters shown on the status bar are as follows:

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Status Shows the overall status of UNITY 2 as it progresses through the various stages of

the sequence - Standby, Leak Test, Trap Heat etc. Status will also report tube

failures i.e. Tube Leaked.

Elapsed Time Shows the time elapsed since the start of the function currently operating on UNITY

2 and should be read in conjunction with the Status parameter. For example if the

Status is reading Prepurge and the Elapsed Time is reading 0.3 this tells us that

UNITY 2 is 0.3 minutes (i.e. 18 seconds) into the ambient purge. If the Status is

reading Primary Desorb and the Elapsed Time is 4.9 - then it is 4.9 minutes since

the start of tube desorption etc.

Pressure Shows the pressure of the carrier gas within the UNITY 2 flow path.

UNITY zones UNITY 2 continually monitors the actual temperature of its internal heated/cooled

zones (tube oven, cold trap, transfer line and heated valve) and the actual carrier

gas pressure and compares them to the set values.

When first switched on UNITY 2 status changes to Standby and the display for UNITY

2 temperature will be highlighted blue until all zones reach the relevant set point.

The Purge Gas indicates whether the dry air or nitrogen is at a high enough pressure

for the Peltier coolers to operate. If Purge Gas is displayed as ‘Off’ then this

indicates that the purge gas pressure is not high enough. In this scenario the Peltier

coolers will be switched off.

NOTE: A run may be started when UNITY 2 is Not Ready and the run will then pause,

waiting for the appropriate zone to reach temperature before desorbing the tube.

The status will read Equilibrating at this stage.

NOTE: The actual temperature of the tube oven has no effect on the ready status as

heat is not applied to the oven until tube desorption starts.

GC Indicates whether the GC status is ready () or not ready ().

See Section 3.2.1 below.

3.2.1 External ready signal

UNITY 2 is connected to the GC via the relevant GC Interface Harness:

SERUTE-5142 Agilent GC

SERUTE-5143 Thermo GC

SERUTE-5144 Varian GC

SERUTE-5141 Other GC (including Shimadzu)

The analytical system should be configured such that all components "downstream" of the GC (e.g. mass

spectrometer, data handling system) must be ready before the GC becomes ready. This ensures that no

sample is injected from UNITY 2 onto the GC when the analytical system is not able to analyse the sample

and collect the data.

When the GC comes ready it will provide a signal to UNITY 2 via the Interface Harness and the GC indicator

on the status bar will change from a cross to a tick. UNITY 2 checks this signal, to ascertain whether the

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GC is ready, twice during its operation sequence, before starting an analysis and/or before desorbing the

cold trap.

3.3 Toolbar functions

The toolbar is used to access commonly used functions within the TD software. A description of each icon

is given below.

Generating a new

method

New methods are generated by either selecting File > New, by clicking the New

File Icon ( ) at the top left-hand side of the toolbar, or by pressing CTRL and N.

A new method screen will be brought up containing a set of default parameters

ready for you to modify. Once the method has been generated it can be named

and saved, see below.

Opening a stored

method

Methods are opened by either selecting File > Open or by clicking the open file

icon ( ) at the top left-hand side of the toolbar. This brings up the directory

(nominated under Options, see Section 3.4.1) containing UNITY 2 method files.

Select the required file name and click OK or double-click on the required file

name to access it.

Saving a method New methods can be saved by

1. Pressing the floppy disk icon ( ) at the left of the tool bar

2. Selecting File > Save

3. Pressing CTRL and S

4. Selecting File > Save As

Using the first three routes brings up the Properties dialogue box. Using route 4

brings up the Method File Directory and allows a file name to be entered for the

method. The Properties dialogue box then automatically appears with the file

name in the appropriate field.

The Method Author and Company names will appear in the Method Properties

dialogue box, as set up under Options, see Section 2.4.1. If nothing has been

entered for these fields under Options the blanks may be filled in at this stage.

The Method Name and Notes sections can be used to provide additional

information on the method if required.

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Method linking Methods can be linked together to perform consecutively on a given tube. This is

most useful where an analytical method is to be followed by a tube conditioning

method or to automate the process of thermal desorption method development.

Method linking is accessed by clicking the Link icon ( ) on the toolbar, or by

selecting Link on the main menu bar.

See Section 3.3.1 for further details.

Print method Select File > Print or click on the print icon ( ) to print the method. This

function will either print the entire method, including properties and gas flows (if

entered), as a text string or will simply print the main method page as it appears

on the computer screen. Method print format is selected under Options, see

Section 3.4.1. Print Preview under the File menu will display the print format on

the screen if needed. It is the active method that is printed.

Copy method

parameters

Ensure that the UNITY 2 method you wish to copy is the active method. Clicking

on it with the left hand mouse button will make it active if necessary.

Select Edit > Copy, or click the copy icon ( ) on the toolbar (the shortcut CTRL

and C can also be used).

Copy will put a "text copy" of the active method onto the Windows Clipboard (in

English Only), thus allowing you to Paste the text string into another application

such as a word processor

Paste Paste is activated after Copy has been used and allows for a copy of the active

method to be pasted to another method (after THAT method has been made

Active).

Note: UNITY 2 does not support pasting from the Windows clipboard i.e. you

cannot paste from the Word processor to UNITY 2

Start run Start run is used to start a desorption sequence.

Start is accessed by clicking the Start Run icon ( ) on the toolbar or selecting

Instrument and then Run.

Set gas flows Used to set the split and desorb flows.

Accessed by clicking the icon

See Section 2.4.3

Trap heat Trap Heat is selected either by selecting Instrument and then selecting Trap Heat,

or by selecting the Trap Heat icon ( ) on the toolbar.

See Section 3.3.2

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Exchange split tube Used to divert any split flow in standby mode so that the split/recollection tube

can be removed without loss of carrier gas.

Accessed by clicking the icon.

See Section 3.6.5

Stop run/sequence The Stop sequence function is used to stop a run or sequence of runs, exit the

Set Gas Flows mode, Exchange split tube mode and Trap Heat procedure.

Stop is accessed by the Stop sequence icon ( ) on the toolbar.

NOTE: If you stop a run at any point after the tube desorption process has started

then some components will have already passed onto the trap which will

therefore need cleaning - along with the GC column - prior to analysing a new

sample.

UNITY 2 schematic This is accessed using the status icon ( ) or by selecting View > Status Show.

See Section 3.3.3

Controlling method Used to assign the active method as the controlling method by clicking the

icon. See Section 3.3.4.

Leak test A leak test may be carried out manually via the leak test icon ( ). Clicking on

this icon opens a dialogue box with a button to pressurise the flow path and to

perform a leak test. The Leak Test function should be used in conjunction with a

He leak detector. The Leak Test dialogue box also allows the valves controlling

the flow path to be operated independently for assistance with diagnosis of

faults. See Section 3.5.2.

Shutdown Peltier

Coolers

Used to turn off the instruments Peltier coolers.

Accessed by clicking on the icon

3.3.1 Method Linking

Once selected, Method linking asks the user to add the relevant methods to the Link table and to indicate

how many injections (repetitions) of each method are to be carried out.



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Method linking sequence which is setup in this example to run two injections with a 2 stage desorption

method followed by a tube conditioning step.

After a method has been run the next method in the sequence is downloaded to UNITY 2 and run. The

procedures to setup and edit linked sequences are:

Open a new sequence

Open an existing sequence

Add an existing method to the link table

Insert a previously stored sequence into

the current sequence

Delete a highlighted method from the

link table

Change the number of injections

Recycle the sequence

[email protected]

which is setup in this example to run two injections with a 2 stage desorption

method followed by a tube conditioning step.


ed sequences are:

Right click and select ‘New Sequence’ to open a new

method linking table.

Right click and select ‘Open Sequence’ to enable the user to

open a previously saved method linking table.

xisting method to the link table Right click and select ‘Add Item’ from the list of options.

The appropriate method can then be selected for the

directory.

Insert a previously stored sequence into Right click and select ‘Add Sequence’ then select the

desired sequence file.

Delete a highlighted method from the Right click and select the ‘Delete Item’ option or press the

delete key on the keyboard.

Double click on the existing number and

appropriate figure from the drop down method. The

software allows 1 - 100 injections of a particular method.

Checking the ‘recycle’ box at the top left corner of the

method linking table. This will recycle the process unt

stopped by the user. However, a set number or recycles can

be selected by checking the ‘stop after’ box, and entering

the appropriate number of repeats in the ‘cycles’ box.

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which is setup in this example to run two injections with a 2 stage desorption


Right click and select ‘New Sequence’ to open a new

Right click and select ‘Open Sequence’ to enable the user to

open a previously saved method linking table.

Right click and select ‘Add Item’ from the list of options.

The appropriate method can then be selected for the

’ then select the

Right click and select the ‘Delete Item’ option or press the

Double click on the existing number and select the

appropriate figure from the drop down method. The

100 injections of a particular method.

Checking the ‘recycle’ box at the top left corner of the

method linking table. This will recycle the process until

stopped by the user. However, a set number or recycles can

be selected by checking the ‘stop after’ box, and entering

the appropriate number of repeats in the ‘cycles’ box.



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NOTE: Should the stop sequence button be pressed during a linking sequence, a

a number of options appears. This enables the user to either continue running, or stop the sequence at

one of the stages listed.

NOTE: GC cycle time will operate in the same manner as a single tube desorption.

3.3.2 The Trap Heat Method

UNITY 2 can use two sets of parameters when undertaking Trap Heat. Either those used in the existing

Controlling Method or a special set of parameters identified as the Trap Heat Method. The choice

between these two is made under Options, see Section 2.4

default Trap Heat conditions whenever this function is accessed.

To view and edit the Trap Heat method click View > Trap Heat Method. The required parameters are

entered in the boxes. Checking the relevant box

Trap Heat is selected either by selecting Instrument and then selecting Trap Heat, or by selecting the Trap

Heat icon ( ) on the toolbar. The following dialogue box then appears.

Once Trap Heat has been selected, UNITY 2 will ask you to confirm that the default method is that which

you wish to use. For example, if the default method was set to Use Controlling Method Parameters then

the box message will read Heat Trap with the Cont

If Yes is selected, UNITY 2 proceeds with trap heat. If No is selected the instrument software immediately

takes you to the relevant section under Options to change your selection.

Also, a ‘Wait for GC Ready, before Heating?’ option is made available. Depending on the response to this

option, UNITY 2 will either wait for an External Ready signal from the GC equipment before proceeding, or

continue the trap heat regardless of the GC status.

Caution: Ensure that the dedicated Trap Heat Method or the Controlling Method, if being used, is

compatible with the maximum temperature of the least stable sorbent in the cold trap.

When using Trap Heat several times to clean a freshly packed trap, it is advisabl

Heat Method and set the Trap Low Temperature to its maximum +50°C, in order to save the time taken

for the system to equilibrate.

Caution: For traps containing carbon molecular sieves Trap Heat Method must not be used until th

trap has been extensively purged with helium immediately prior to Trap Heat. Refer to the

cold trap certificate supplied with your trap for further information.

[email protected]

Should the stop sequence button be pressed during a linking sequence, a dialogue box containing


GC cycle time will operate in the same manner as a single tube desorption.



between these two is made under Options, see Section 2.4. The selected option will then appear as the

default Trap Heat conditions whenever this function is accessed.


entered in the boxes. Checking the relevant boxes will activate the split on during trap heat / standby.


) on the toolbar. The following dialogue box then appears.



the box message will read Heat Trap with the Controlling Method Parameters? Select Yes, No, or Cancel.


takes you to the relevant section under Options to change your selection.

GC Ready, before Heating?’ option is made available. Depending on the response to this


continue the trap heat regardless of the GC status.

Ensure that the dedicated Trap Heat Method or the Controlling Method, if being used, is


When using Trap Heat several times to clean a freshly packed trap, it is advisable to use a dedicated Trap


or traps containing carbon molecular sieves Trap Heat Method must not be used until th

has been extensively purged with helium immediately prior to Trap Heat. Refer to the

cold trap certificate supplied with your trap for further information.

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dialogue box containing




. The selected option will then appear as the


es will activate the split on during trap heat / standby.




rolling Method Parameters? Select Yes, No, or Cancel.


GC Ready, before Heating?’ option is made available. Depending on the response to this


Ensure that the dedicated Trap Heat Method or the Controlling Method, if being used, is


e to use a dedicated Trap


or traps containing carbon molecular sieves Trap Heat Method must not be used until the

has been extensively purged with helium immediately prior to Trap Heat. Refer to the



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3.3.3 Schematic display of UNITY 2 status

A simple schematic illustrating the status of UNITY 2

system operation.

This is accessed using the status icon (

The schematic display of UNITY 2 status is linked directly to operation of the instrument. The di

thus not just cosmetic, but is a representation of the actual status of the instrument.

3.3.4 Controlling method

One method is identified by UNITY 2 as that controlling the system i.e. the method dictating the set

parameters. This method is called the C

method is loaded as the controlling method.

To load another method use either the Load icon or select File and then Load from the menu. The loaded

method will not automatically become the co

as such in the bar at the top of its window, whether active or not.

To make a loaded method the controlling method, select it (to make it the active method) then click the

icon. Once set UNITY 2 immediately starts to set the new parameters. The instrument status

changes accordingly. Only one method is identified as the controlling method at any one time.

NOTE: An active method is not necessarily the controlling method. The active method

modified or accessed by the operator.

3.4 UNITY 2 Options

The Options page is accessed in the UNITY 2 software via ‘View > Options’

[email protected]

Schematic display of UNITY 2 status

A simple schematic illustrating the status of UNITY 2 can be displayed on the screen at all times during

This is accessed using the status icon ( ) or by selecting View and then Status Show.

The schematic display of UNITY 2 status is linked directly to operation of the instrument. The di

thus not just cosmetic, but is a representation of the actual status of the instrument.


parameters. This method is called the Controlling Method and cannot be deleted or closed until another

method is loaded as the controlling method.


method will not automatically become the controlling method. The controlling method is always identified

as such in the bar at the top of its window, whether active or not.


TY 2 immediately starts to set the new parameters. The instrument status


An active method is not necessarily the controlling method. The active method

modified or accessed by the operator.

The Options page is accessed in the UNITY 2 software via ‘View > Options’

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can be displayed on the screen at all times during

) or by selecting View and then Status Show.

The schematic display of UNITY 2 status is linked directly to operation of the instrument. The display is


ontrolling Method and cannot be deleted or closed until another


ntrolling method. The controlling method is always identified


TY 2 immediately starts to set the new parameters. The instrument status


An active method is not necessarily the controlling method. The active method is simply that last



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3.4.1 Configuration

The configuration page contains the current instrument configuration settings.

Instrument Configuration

For UNITY 2 operation the Instrument Configuration will be set to UNITY (manual).

Communications Port

The communications port determines serial port number (e.g. Com1) that is used for communicating with

UNITY.

Sequence Options – Enable Direct Mode

If the Enable Direct Mode option is selected an additional mode of operation will be available. Additional

hardware is required for this mode to be used correctly. Direct mode is only required when the any of the

following hardware accessories are installed:

U-INLET accessory.

[email protected]

The configuration page contains the current instrument configuration settings.

For UNITY 2 operation the Instrument Configuration will be set to UNITY (manual).


Enable Direct Mode



cessories are installed:

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Markes H5-TD accessory.

Connection to an external headspace autosampler (e.g. Agilent G1888 Headspace system).

Sequence Options – Post Tube Desorb Pressure Release Time

Pressure can be released from a sample tube prior to completion of desorption. This reduces the potential

loss of adsorbent from a pressurised tube, particularly if the tube has no gauze fitted to restrain the

adsorbent, as it is removed from UNITY 2 flow path. sets the time taken to release the carrier gas pressure

in the tube at the end of tube desorption. The default is 0.3 min.

Enable extended standby

In extended standby the Peltier coolers will be switched off. When enabled the time-out period before

which extended standby is entered can be set.

NOTE: The time-out period only starts once the instrument has entered standby.

3.4.2 GC Interface

Used to set the GC Interface logic.

The GC Interface logic is set to reflect whether the GC sense is Open or Closed for both GC Start (Out) and

GC Ready (In) i.e. for the particular GC being used is the contact Open or Closed to reflect a Start signal,

and Open or Closed to reflect a Ready signal. This information is usually provided in the GC Users Manual.

3.4.3 Gas & Flow

This page contains all settings for the carrier gas and mass flow controllers. If an MFC has been installed

on UNITY 2 it is configured under the Flow Control section of this page. For further information please

refer the MFC installation manual.

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The Carrier Gas being used can be set using the drop down box.

NOTE: Carrier type only needs to be set when using MFCs.

The carrier gas pressure as measured by the pressure transducer, within the UNITY 2, can be displayed in

either psi or kPa depending upon preference, and is selected here.

3.4.4 Methods

This is accessed by selecting ‘View > Options > Methods’. There are two method functions which can be

changed.

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Paths – Method Dir

Set by default to the directory where UNITY 2 is installed. To change this directory double click on the

current path and select the new path from the directory.

Paths – Show Full Path

If selected then the active window bar will show the full path and file name of the method in the active

window bar, if it is not selected then the active window bar will only display the file name for that method.

Paths – Show Method Path

If selected then the active window bar will show the text entered in the Method Name section of the

properties dialogue box.

Paths – Show Method Name

If selected then the active window bar will show the file name of the method in use, with or without the full

path depending on whether Show Full Path is selected.

Trap Heat Method

UNITY 2 can use one of two sets of parameters when undertaking Trap Heat. Either those used in the

existing Controlling Method or a special set of parameters identified as the Dedicated Trap Heat Method.

The choice between these two is made here. See section 3.3.2 for further details.

User Details

Details of the Author and Company which will automatically appear in the properties dialogue of each

saved method.

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3.4.5 Reporting

This option influences the information recorded in the ‘sequence reporter’ page of method linking, see

Section 3.3.1. Recording parameters are selected by clicking on the appropriate box(es).

NOTE: the reporting options available will change if an accessory is being used in conjunction with UNITY

2.

Method Name

Displays the name of the method used.

Desorb Start Time

Displays the time at which tube desorption started.

Desorb End Time

Displays the time at which tube desorption was completed.

Peak Desorb Temp

Displays the maximum temperature the tube oven reached during the analysis.

Trap Fire Time

Displays the time at which the cold trap desorption started (and therefore the time at which a GC

connected to the UNITY would have been triggered to start).

Unity Deviation

Displays any error messages encountered during operation (e.g. Tube Leaked)

Injection Count

Displays the number of times a given sample has been analysed.

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Cycle Count

Displays the number of sequence cycles that have been completed.

3.5 UNITY 2 method options

3.5.1 Split on or off in standby

When UNITY 2 is in standby state, i.e. not being used overnight or at weekends, it is usual to have the split

turned off in order to save expensive carrier gas (8 hours overnight at 50 ml/min would use ~24 litres of

carrier gas).

However if UNITY 2 is being operated with a mass spectrometer (MS) or an electron capture detector

(ECD) on the gas chromatograph, it is strongly recommended that the split be left on in standby [if there is

no positive gas flow passing through the split vent for long periods of time, air will enter the system

through the split vent and cause an undesirable increase in background signal. This is common to all split

capillary injectors].

The split flow may be reduced to 10 ml/min to minimise carrier gas consumption if required.

Checking the box on the top line of the method page selects Split On in Standby. An unchecked box will

turn the Split Off in Standby.

3.5.2 The Leak Test

Once in position in the desorber flow path, each tube is pressure tested, without heat or carrier gas flow,

to ensure there are no leaks. The test is deliberately stringent. If sample tubes fail to seal properly or if a

leak develops in any other part of the system flow path, data obtained from that analysis would be invalid.

Every part of the UNITY 2 flow path, including the main valve, is tested for leaks during the pressure test

(the only exception is the point where the transfer line is connected to UNITY 2). For this reason, following

installation of the transfer line, it is recommended that a leak detector is used to detect any leaks at this

point in the flow path. Many competitive thermal desorption systems do not offer such a comprehensive

leak test. Without this, there is always risk of an undetected leak and data integrity cannot be guaranteed.

The 'no-heat, no-flow' specification ensures that sample integrity is maintained while the UNITY 2 leak test

is in progress. If the tube fails the leak test, it will not be analysed and UNITY 2 displays a Tube leaked

error message in the status box on the main status bar. The user must clear this message by pressing the

Stop sequence icon ( ) on the tool bar, before proceeding.

3.5.3 Determining the prepurge time

The flow through the sample tube during the ambient temperature purge is controlled as follows:

Trap in line, split off purge flow controlled via the needle valve on the desorb flow vent

Trap off line, split on purge flow controlled via the needle valve on the split vent

Trap in line, split on total purge flow = flow through cold trap (controlled via the needle valve

on the desorb flow vent) + flow through split vent (controlled by the needle

valve on the split vent)

The Prepurge time should be set such that, with the given purge flow, the necessary purge volume is

passed through the sample tube before the end of ambient purge and the beginning of tube heat. Typical



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prepurge times are 1-3 minutes for normal sorbents and materials samples and 10 minutes for molecular

sieves and carbonised molecular sieves.

3.6 Desorption modes

Two modes are available:

Standard 2(3) Stage Desorption

Tube Conditioning

Select between the modes by using the up and down arrows or

left clicking the desired option.

3.6.1 Tube conditioning mode

This mode is used to condition sorbent tubes prior to sampling.

Freshly packed sorbent tubes, including the Tenax tube shipped with UNITY 2, will require conditioning

prior to use. There are several points to note when conditioning sample tubes using UNITY 2 as opposed

to an external Tube Conditioning/Dry-Purge Rig (e.g. a TC20).

Always use the dedicated Tube Conditioning Mode so that contaminants from the tube are vented to the

charcoal filter and are not passed onto the cold trap.

Set the split flow to at least 50 ml/min (preferably 100 ml/min) to assist efficient conditioning.

Carefully double-check the maximum isothermal temperature for the sorbent in use. We advise restricting

the conditioning temperature to at least 10°C below this sorbent maximum.

Set the flow path temp to at least 190°C while conditioning tubes. This prevents contaminants f

condensing inside the UNITY 2 flow path and helps to condition the system.

In tube conditioning mode, the cold trap is off line all the time so that desorbed materials cannot

contaminate this or the GC analytical column.

Method parameters may either be entered by clicking on each box in turn, typing in the parameter and

then pressing Enter or by entering in the first parameter and then using the tab key to automatically enter

the parameter and move the cursor to the next active box. The last parameter

completed by pressing Enter.

Only a few of the usual thermal desorption parameters are relevant in a Tube Conditioning Method:

Mode Set to Tube Conditioning.

Split on in Standby Click on the box to enter a check if Split On in

Prepurge Set Prepurge time by clicking in box and typing the required time. 1 minute

at 30 ml/min is enough to purge oxygen from most sorbent tubes. However,

this should be extended to 5 or 10 mins at 30 ml/min for molecular sieve

and carbonised molecular sieve type sorbents.

Note: The cold trap is, by default, off line during ambient purge in tube

conditioning mode. The split flow is therefore switched on by default.

Tube Desorb The desorb time

clicking in the relevant boxes and typing in the required values. The split

[email protected]

3 minutes for normal sorbents and materials samples and 10 minutes for molecular

sieves and carbonised molecular sieves.

Select between the modes by using the up and down arrows or

This mode is used to condition sorbent tubes prior to sampling.

including the Tenax tube shipped with UNITY 2, will require conditioning


Purge Rig (e.g. a TC20).

dicated Tube Conditioning Mode so that contaminants from the tube are vented to the

charcoal filter and are not passed onto the cold trap.


heck the maximum isothermal temperature for the sorbent in use. We advise restricting

the conditioning temperature to at least 10°C below this sorbent maximum.

Set the flow path temp to at least 190°C while conditioning tubes. This prevents contaminants f

condensing inside the UNITY 2 flow path and helps to condition the system.


contaminate this or the GC analytical column.

be entered by clicking on each box in turn, typing in the parameter and


the parameter and move the cursor to the next active box. The last parameter change should always be


Set to Tube Conditioning.

Click on the box to enter a check if Split On in Standby is required.

Set Prepurge time by clicking in box and typing the required time. 1 minute



nd carbonised molecular sieve type sorbents.



The desorb time - Time 1 - and desorption temperature -


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3 minutes for normal sorbents and materials samples and 10 minutes for molecular

including the Tenax tube shipped with UNITY 2, will require conditioning


dicated Tube Conditioning Mode so that contaminants from the tube are vented to the


heck the maximum isothermal temperature for the sorbent in use. We advise restricting

Set the flow path temp to at least 190°C while conditioning tubes. This prevents contaminants from


be entered by clicking on each box in turn, typing in the parameter and


change should always be


Standby is required.

Set Prepurge time by clicking in box and typing the required time. 1 minute





Temp 1 - are set by


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flow is automatically switched on during tube desorption in this mode. The

gas flow through the sample tube is controlled by the needle valve on the

split flow vent.

It is recommended that a split flow of at least 50 ml/min be used during

tube conditioning.

Flow Path Temp Set the temperature required for the sample flow path by clicking in the box

and typing in the required value. High temperatures (180 to 210°C) are

recommended during tube conditioning.

Min Carrier Pressure Set a minimum carrier gas pressure just below that at which you normally

operate UNITY 2 and the GC analytical column. If the carrier gas pressure

drops below this minimum pressure, UNITY 2 status will change to Low

Carrier Pressure and UNITY 2 will become Not Ready. This prevents tubes

being heated with a low carrier gas supply which could damage the sorbents

in the tube.

3.6.2 Standard 2(3) stage desorption

Standard 2(3) stage desorption is the mode used for most routine thermal desorption work.

Mode Set to Standard 2(3) stage desorption.

Split on in Standby Click on the box to enter a check if Split On in Standby is required.

Prepurge Set the ambient Prepurge Time by clicking in the relevant box and typing the

required time (See Section 22.1.1 for advice on prepurge times).

If required, select Trap In Line during the prepurge by clicking on the box to

enter a check. Similarly, click on the Split On box to enter a check if a split is

required during the prepurge. Remember one or other or both of these flows

must be selected during the prepurge.

Tube Desorb Set the Time 1 - desorption time - and the Temp 1 - desorption purge

temperature - by clicking in the relevant boxes and typing in the required values.

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Tube desorption may be carried out split or splitless i.e. all the sample from the

sample tube can be transferred to the trap or part of it sent to the split vent. If a

split is required during tube desorption (a so-called inlet split, see Section 1.4)

check the relevant box. If the split is selected to be off during tube desorption,

all the analytes will be transferred from the tube to the cold trap.

If an elevated temperature purge is required, see Section 2.6.4, then Time 1

and Temp 1 should be set to reflect the required elevated Prepurge time and

temperature. In this case, Time 2 and Temp 2 become the actual analytical tube

desorption time and temperature and time values should be entered

appropriately.

Typical elevated temperature purge settings are 5-15 minutes at 50-100°C.

Trap Desorb Set the Trap Low temperature by clicking in the box and typing in the required

value.

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Most applications work well with a Trap Low of -10°C. Obvious exceptions to

this include the analysis of samples containing high levels of water or standards

containing unwanted solvent. In these cases it may be useful to maintain a Trap

Low temperature at or near ambient (25-30°C). This allows water and volatile

solvents such as methanol and methylene chloride to breakthrough the trap

(depending on which sorbents are in the trap) and be eliminated from the

system before trap desorption and the beginning of the chromatographic

analysis.

Set the Trap High temperature as appropriate for the trap sorbent and target

analytes. The correct Trap Hold time should ensure all analytes are desorbed

from the trap and that the trap is again clean and ready to use for the next

sample. This is typically set to 3 minutes.

Trap desorption can be carried out split or splitless i.e. if a split is required

during trap desorption (a so-called outlet split, see Section 1.4), check the

relevant box. If the split is selected to be off during trap desorption, all the

analytes will be transferred from the trap to the GC analytical column during

desorption.

The flow through the trap when it is hot = the flow through the GC column plus

that through the split vent, if any.

Flow Path Temp

Set the temperature required for the heated valve and sample flow path by

clicking in the box and typing in the required value. The following general

guidelines may be applied:

All analytes, volatile enough to be present in the air in the vapour phase at

ambient temperature, will pass comfortably through the system with the flow

path between 120°C and 150°C.

For ease of use, extended system lifetime and trace level operation a lower

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temperature (e.g. system default temperature of 140°C) is often preferred.

Whenever analysing labile compounds use a low (<100°C) flow path

temperature and, where possible, increase gas flow rates (linear gas velocities)

inside the system.

Use the highest possible flow path temperature (200 - 210°C) for analysing

semi volatile organics.

Min Carrier Pressure Set a minimum carrier gas pressure below that at which UNITY 2 is normally

operated. If the carrier gas pressure drops below this minimum pressure, UNITY

2 status will change to Low Carrier Pressure and UNITY 2 status will read Not

Ready. If the carrier gas pressure drops below the minimum pressure during a

run, UNITY 2 will enter Low Carrier Gas status and the tube oven (if heating) and

trap heater (if heating) will start to cool down.

GC Cycle Time The GC Cycle Time = GC Run Time + GC Cool Down Time + Equilibration (if

appropriate).

If a GC Cycle Time is entered, UNITY 2 will calculate the time at which it can

begin the next tube desorption stage such that at the end of that tube

desorption and at the time the trap is ready to heat, the GC will have just come

ready from the previous analysis. To enter a GC Cycle Time click in the relevant

box and type in the required value.

Split Ratios – split

flow calculator

NOTE: This tool only calculates the split flows – it does not set them.

The inlet, outlet and total split ratios can be viewed, when applicable, in the box

at the bottom right hand corner of the method page once the measured flows

have been entered into the method.

Flows may be entered by clicking on the Confirm/Enter Flows button to bring

up the relevant dialogue box.

Once the values have been entered and confirmed by pressing OK, the split

ratios are automatically calculated and displayed.

For measurement of gas flows see Section 1.4.4.

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3.6.3 Sample tube prepurge

With normal porous polymer or graphitised carbon sorbents, a volume of carrier gas, ~ 10 times the

capacity of the sample tube, is required to completely eliminate air. This equates to 20 ml purge volume

for glass tubes (capacity ~2 ml) and 30 ml purge volume for stainless steel tubes (capacity ~ 3 ml). A

more stringent purge (~50 times the tube volume) is required to completely eliminate air from tubes

packed with conventional or carbonised molecular sieve-type sorbents.

Control of the carrier gas flows during ambient purge

The ambient purge carrier gas flow can either pass through the cold trap to the 'desorb flow' vent or

through the split filter to the 'split flow' vent or both as it comes out of the sample tube.

Trap in or out of line

The cold trap is user selectable to be in or out of line during the ambient temperature purge. It is generally

recommended for the cold trap to be off line at this stage, to ensure that any water purged from the tube

is not re-trapped on the cold trap. Applications involving the direct desorption of volatile components from

materials such as pharmaceuticals, plastics etc. are an exception to this rule. In these cases, and

especially if the material contains ultra volatile target analytes such as acetaldehyde, it is advisable to

have the trap in line.

Split on or off

If the trap is selected to be off line during tube purge (the most usual configuration), by default the split

flow is always turned on to give a flow through the tube.

If the trap is selected to be in line the user has a choice of whether the split vent is on or off. The split

should be selected to be the same as during the tube desorb process and is therefore determined by the

sensitivity of the analysis. Further information on selecting and setting split flows is given in Section 3.4.

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3.6.4 Sample tube prepurge at elevated temperature

The elevated purge option is used for selectively eliminating water and/or high levels of unwanted volatile

components. The trap is, by definition, almost always out of line during elevated temperature purge,

which means that the split flow must be on. The elevated temperature purge immediately follows, and

does not replace, the ambient temperature purge.

Example applications are:

Eliminating high levels of water collected on sorbent tubes when monitoring humid atmospheres.

Eliminating high levels of ethanol from a sample of the flavour profile of potable spirits when the

components of interest are higher boiling esters and ketones.

Eliminating high levels of volatile solvent from higher boiling (e.g. aromatic) standards introduced onto

sorbent tubes as droplets of liquid solution.

It is the entry of the second tube desorb time (Time 2) in the appropriate box, which indicates to the

system that an elevated temperature purge is required. When a value is entered for Time 2 an extra Trap

In Line check box appears in the line referring to stage 1 of tube desorb. As stage 1 of tube desorb is now,

effectively, an elevated temperature purge, it becomes appropriate, as in ambient temperature purge, to

deselect the cold trap. The cold trap is invariably selected off-line and the split flow on during elevated

temperature purge because the purpose of elevated temperature purge is generally to eliminate volaties

from the tube and system before analysis of higher boiling target analytes.

Gas flows during elevated temperature purge are controlled as described in Section 2.6.2 for the ambient

temperature purge.

When using 2 stages of tube desorption, remember to place a check in the second split on box if an inlet

split is required for the analysis. The gas flow through the hot tube during its analytical desorption = the

flow through the cold trap (the so-called desorb flow - controlled via needle valve) + the inlet split flow i.e.

the flow through the split vent (also controlled via needle valve), if any.

3.6.5 SecureTD-Q™ - Re-collection for repeat analysis

UNITY 2 facilitates the quantitative re-collection of the split portion of a sample onto a clean sorbent tube

thus facilitating repeat analysis. This is of real benefit in situations where it is not possible, or prohibitively

expensive, to collect replicate samples.

To re-collect the split effluent, the normal charcoal-packed split filter tube (SERUTD-5065) supplied with

UNITY 2 must be replaced with a conditioned sorbent tube - the SecureTD-Q tube.

NOTE: This procedure should only be carried out with the system in standby mode.

In order to access the tube on the split side (charcoal or SecureTD-Q), the exchange split tube icon ( )

must be selected. This will isolate the split tube from the carrier gas supply without disrupting the flow to

the analytical column allowing chromatography to continue uninterrupted as the SecureTD-Q and charcoal

tubes are exchanged.

Once ‘exchange split tube’ has been selected, lift the right-hand levered tube cover to release the charcoal

split tube from one of its seals. Use your fingers or the tube extractor tool to gently pull the tube free from

the other seal. Once the charcoal tube has been removed, the clean (SecureTD-Q) sorbent tube should be

inserted with its sampling (grooved) end pointing to the rear of the instrument. Lower the right-hand

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levered tube cover to seal it into position then press the stop icon ( ) to return the carrier gas flow path

to normal standby status.

If the sample is being re-collected during an analysis, re-activate the ‘exchange split tube’ icon as soon as

the desorber returns to standby mode after trap desorption. Remove the re-collected sample using the

above procedure and cap it immediately. Insert another clean (SecureTD-Q) sorbent tube or the charcoal

split tube as required, and press the stop icon ( ) to return to normal standby mode.

NOTE: SecureTD-Q will not work for methods that are operated entirely splitless. Either an inlet or outlet

split or both are required.

As well as repeat analysis, SecureTD simplifies method development, provides a convenient method

validation tool and allows critical samples to be archived when required.

For further information on split re-collection for repeat analysis see TDTS 24.

3.6.6 Cold Trap conditioning

Before using for sample analysis, the cold trap must be cleaned/conditioned. If the cold trap contains no

molecular sieve or carbonised molecular sieve type sorbents, trap conditioning is most easily achieved

using the Trap Heat function on UNITY 2 (see Section 2.3.2.). As with tube conditioning it is essential to

check the maximum isothermal temperature of the sorbent in the trap and never to set the trap

temperature more than 10°C below this. In addition, use a split flow of at least 50 ml/min to ensure

efficient conditioning of the trap and to reduce the mass of contamination allowed to reach the analytical

column.

For cold traps containing molecular sieve sorbents refer to the relevant cold trap certificate and purge the

trap with sufficient quantity of helium prior to operating the Trap Heat Method.

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3.6.7 UNITY 2 parameter specifications

Parameter Range

Mode Standard 2(3) Stage Thermal Desorption

Tube Conditioning

Split on in standby Yes/No

Ambient temperature carrier gas purge Time settable between 0.0 and 99.9 minutes in

0.1 minute increments

Split on during tube purge Yes/No

Trap in-line during tube purge Yes/No

Elevated temperature purge or stage 1 of primary

(tube) desorption (optional)

35 to 400°C (settable in 1° increments) for 0 to

999.9 minutes (settable in 0.1 minute

increments)

Trap in-line during elevated tube purge Yes/No

Split on during elevated tube purge Yes/No

Primary tube desorption (stage 2 if optional

elevated temp. purge employed)


999 minutes (settable in 0.1 minute increments)

Split on during primary (tube) desorption Yes/No

Cold trap focusing temperature -30 to +50°C (settable in 1° increments)

Cold trap (secondary) desorption temperature

minutes


99.9 (settable in 1 minute increments)

Cold trap heating rate Max (ballistic heating reaching 100°C/sec during

first critical stages of trap heat) or options

between 1° and 40°C/sec

Split on during secondary (trap) desorption Yes/No

Flow Path Temperature 50 to 225°C

GC Cycle Time 0 to 999.9 minutes

Minimum Carrier Gas Pressure 0.0 to 99.0 psi

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3.7 Uninstalling UNITY 2 software

When new UNITY 2 software is issued it is important that any previous installations of software are

completely removed prior to installing the new version.

In order to ensure that the PC system is correctly purged of all relevant files it is necessary to follow these

instructions fully.

As with any Windows software the correct way to uninstall the software is to use the Add/Remove

Programs option from the Control Panel. Exactly how this is done will depend upon the version of

Windows.

3.7.1 Windows 7

1. Click on the start button and select control panel.

2. Under Programs click on Uninstall a program.

3. Scroll down the list presented and select Markes TD 5.1.0

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4. Select Uninstall/Change Program and follow the on screen prompts (when asked to remove shared

files click yes). The Markes TD software should now be uninstalled.

3.7.2 Windows Vista

1. Click on the start button and select control panel.

2. In the control panel select Programs and Features.


4. Right click and select Uninstall/Change Program and follow the on screen prompts (when asked to

remove shared files click yes). The Markes TD software should now be uninstalled.

3.7.3 Windows XP

1. Click on the Start button and select Control Panel.

2. In the Control Panel select Add/Remove Programs.


4. Click on Add/Remove and follow the on screen prompts (when asked to remove shared files click

yes). The Markes TD software should now be uninstalled.

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4. Accessing product and support information

4.1 Markes International Limited - Home Page and facilities

Markes International can be accessed at: www.markes.com where details of new products, applications,

and technical help are available.

Registration (www.markes.com/registration) allows you to access further technical information.

4.2 Consumables and Spares

An up to date list of available consumable items is given in the brochure ‘Focusing on Volatiles’ which is

available from Markes International Ltd. direct on

Email [email protected]

Fax +44 (0) 1443 231531

For itemised spares please refer to the shipping kit list in Section 5.1.

4.3 Applications library

Information on thermal desorption applications can be obtained from your Markes International sales

office. Alternatively contact Markes International Ltd. direct on:

Email [email protected]

Fax +44 (0) 1443 231531

4.4 Technical support

In the first instance please contact your local Markes International sales office. Alternatively, contact

Markes International Ltd. direct on

Email: [email protected]

Fax: +44 (0) 1443 231531

Tel: +44 (0) 1443 230935

Please provide as much information as possible, including your instrument serial number(s).

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5. Technical Support

5.1 Routine maintenance schedule

A routine maintenance kit is available for UNITY 2 (RMK-0001-2S) containing all UNITY 2 consumables

that are required for an annual service.

UNITY 2 ITEMS Frequency

Check Oxygen / organics trap - replace if necessary Weekly

Sample tubes - repack / replace 200 desorptions

Change the charcoal filters (split tube) 3 months

Cold trap – repack / replace 12 months

Cold trap seals Only if damaged / leak test failing

Replace sample tube seals and filters Only if damaged / leak test failing

UltrA ITEMS

Replace DiffLok cap o-rings Only if damaged / leak test failing

Change nozzle seals Only if damaged / leak test failing

5.2 Sorbent Tubes

5.2.1 Packing tubes

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Ensure that empty tubes are fitted with a sorbent retaining gauze in the correct position at the front of the

tube - the position of this gauze is critical for diffusive sampling. (Factory supplied empty tubes arrive with

the gauze pre-fitted). Insert a quantity of quartz wool after the gauss to prevent migration of fine sorbent

particles out of the tube.

Tubes should be gravity filled with sorbent (not filled under pressure). For compliance with International

Standards and accreditation schemes the mass of sorbent packed into the tube should be measured and

recorded.

Once the appropriate mass of sorbent has been poured into the tube a few taps on a hard surface will be

sufficient to settle the packing.

A small amount of quartz wool should be inserted followed by a second sorbent retaining gauze, inserted

using a TubeMate (C-TBMTE) or other suitable tool, until the gauze sits firmly on top of the sorbent

(without compressing the packing).

A gauze retaining spring is then inserted using the TubeMate to hold the gauze in place.

Tubes should be impedence tested prior to use

A range of pre-packed sorbent tubes is available from Markes International (see relevant Accessories for

Thermal Desorption catalogue or contact Markes on [email protected] )

5.2.2 Lifespan of tubes

The lifespan of a freshly packed tube will depend upon the following:

The sorbent type

The maximum temperature the tube has been desorbed at

The temperature the tube has routinely been desorbed at

The number of desorption cycles (analytical and tube conditioning) it has undertaken

Assuming the sorbents have not been taken over their maximum temperatures, Tenax TA tubes and tubes

packed with carbon based sorbents are good for 100 - 200 cycles, other porous polymers such as

Chromosorb, Porapak and HayeSep tubes should be re-packed once they have undergone 100 thermal

cycles.

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5.2.3 Conditioning tubes

Tubes will require conditioning when freshly

packed and when they have been stored for

longer than 24 hours (for trace level analysis)

or 7 days (for ppm level analysis), without

being fitted with ¼-inch brass storage caps.

Tubes should be cleaned using the dedicated

tube conditioning mode on UNITY or using the

TC-20 Multi tube conditioning rig.

See Application information (TDTS 5 /

TDTS19) for further details.

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5.2.4 Long term storage of clean and sampled tubes

Conditioned or sampled tubes should always

be stored using ¼-inch brass Swagelok-type

screw caps fitted with combined PTFE ferrules

(C-CFO20 (pk20), C-CF200 (pk200)). It is

recommended that these be tightened by

hand plus a further quarter turn using

conventional spanners or ideally a Markes

International Ltd. CapLok tool (C-CPLOK).

It is not necessary to store capped tubes in refrigerated conditions unless they are sampled, multibed

tubes in which case refrigeration may be required to prevent analyte migration to the stronger sorbents.

In fact in most cases differential contraction of the tubes and seals at fridge or freezer temperatures can

cause the caps to come loose. If refrigeration is to be used, caps must be retightened (a quarter turn)

once they have reached their storage temperature.

NOTE: A tube should be allowed to warm up and equilibrate properly at ambient temperature before the

beginning of sampling. If this is not done, a significant mass of water from the atmosphere will be retained

in the tube via simple condensation.

NOTE: If tubes are to be transported in such a way as to be exposed to very cold temperatures, it is

advisable to follow the above retightening procedure by cooling the tubes prior to shipment. When

monitoring trace level atmospheric components, conditioned and sampled tubes can be wrapped in

uncoated aluminum foil and / or placed in a sealed, non-outgassing container, such as an uncoated tin,

during transportation and storage.

5.2.5 Changing tube seals and filters

The tube O-ring seals (U-COV10 (pk 10), U-

COV100 (pk 100)) are found at either end of

the tube sealing mechanism. UNITY should be

switched off before O-rings are removed or

replaced.

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If they are required to be changed they should

be hooked out with the O-Ring extraction tool

(SERZ-0351) from the shipping kit.

Use the same pointed implement to hook out

the PTFE filter disks.

The clean filters (U-DISK1) should be pushed

in with the O-Ring insertion tool (SERZ-0285)

or with any clean, flat-ended metal rod of

suitable diameter.

New O-rings should also be pushed into

position using the O-Ring insertion tool

supplied in the shipping kit.

Also use the O-Ring insertion tool to smooth

around the inner diameter of the O-Ring as it

is being pushed into place to avoid distortion.

5.2.6 Changing the charcoal split tube filters

If you are not recollecting the split effluent for subsequent analysis, the charcoal filters will trap the split

effluent to prevent it being vented to the atmosphere. Therefore the filters will require changing at routine

intervals.

SERUTD-5065 Split Filter Tube Packed with Charcoal (UNITY 2)

SERAAA-1600 Split Filter Tube, Glass, Packed with Charcoal (Air Server systems)

It is suggested that the filters are repacked with conditioned charcoal every three months. Charcoal filters

are loaded in the same manner as tubes, with the grooved end (or fritted end of the glass tube) facing the

back of UNITY.

Once the split tube has been isolated from the carrier gas flow by selecting the ‘Change Split Tube’ icon,

remove the charcoal tube by lifting the black knob of the sealing mechanism and using the Tube Extractor

tool (SERUTD-5062) to grip the charcoal tube and remove it from the seal.

5.2.7 Changing DiffLok cap o-rings (UltrA)

It is rare for the O-rings in the DiffLok caps (U-COV10 / U-COV100) to require replacing, however if

necessary (O-rings have become worn or badly contaminated), then it is a simple operation to remove the

O-rings and replace using the following O-ring extraction tool (SERZ-0351) and insertion tool (SERZ-0285).

Spare DiffLok caps are available as follows:

C-DLS10 Cap, DiffLok, inert coated, pk 10 - for use on hot end

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C-DL1S0 Cap, DiffLok, inert coated, pk 100 - for use on hot end

C-DL010 Cap, DiffLok, st. st. pk 10 – for use on cold end

C-DL100 Cap, DiffLok, st. st. pk 100 – for use on cold end

C-DLP10 Cap, DiffLok, inert coated / st. st, pk 10 pairs

C-DL1P0 Cap, DiffLok, inert coated / st. st, pk 100 pairs

2.7 Changing the nozzle seals (UltrA)

NOTE: Before proceeding ensure that UltrA and UNITY 2 are switched off by closing down the software

and switching off the main power switch at the back of the instruments.

The required parts are:

U-COV07 O-ring, Size 007, pk 10

SERZ-0351 O-ring extraction tool

SERZ-0285 O-ring insertion tool

To gain access to the nozzle seals,

remove the interface tube of the heated

interface from UNITY 2 and the three

rear covers from UltrA - as described in

the UltrA installation manual.

Release the two securing screws

holding the oven retaining bracket in

place and slide temporarily upwards in

the frame to release the oven.



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To gain access to the nozzle / seal

assemblies, rotate the oven assembly

around its hinge point towards the back

of the instrument. This allows access to

both hot and cold nozzle assemblies.

Using the suggested tools, replace the

O-rings in both nozzle assemblies as

required.

Ensure the new O-ring(s) are correctly

seated and damage free.

5.3 Cold Trap

5.3.1 Packing / conditioning a cold trap

Ready-packed traps are available from Markes International Ltd.

Empty trap tubes (U-T7EMP-2S) are also

is constructed of quartz. It is fragile and should be packed with care.

Empty cold traps should be packed from the wider (2 mm) bore end using the following procedure.

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assemblies, rotate the oven assembly

around its hinge point towards the back

of the instrument. This allows access to

both hot and cold nozzle assemblies.

Using the suggested tools, replace the

ring(s) are correctly

Packing / conditioning a cold trap

packed traps are available from Markes International Ltd.

2S) are also available for the user to pack as required. The UNITY 2 cold trap

is constructed of quartz. It is fragile and should be packed with care.


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available for the user to pack as required. The UNITY 2 cold trap


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First insert a 2-5 mm plug of quartz or glass wool using a suitable flexible tool such as a 15 cm length of

1/16 -inch, narrow bore plastic tubing (PTFE or PEEK tubing is ideal.)

Pour in the required amount of sorbent. Analytes enter and desorb from the trap through the restricted

end. Multibed traps must therefore be packed with the sorbents arranged in order of increasing strength

from the narrow end. 1 to 3 mm plugs of quartz wool must separate different sorbents.

Plug the end of the trap with another glass wool plug, backed with a packing retaining spring.

If unsilanised glass (rather than quartz) wool is used in the cold trap, it may cause degradation and / or

tailing of polar and labile compounds. Silanised glass wool does not suffer from these limitations but

must not be taken above 275 °C or breakdown products from the silylating reagent will coat the sample

flow path of the desorber, reducing recovery of high boiling compounds.

NOTE: A 6 cm length of the wider bore section of the trap tube, measured from the point of the bore

restriction, is subjected to full cooling and heating power. The trap packing, including all but the

back glass / quartz wool plug, should be within this 6 cm length of the trap

NOTE: Do not over-compress the cold trap packing as this will cause high impedance, which may limit

trap desorption flows.

If high trap desorption flows will be required, for example when using a high split ratio, use 40-60 rather

than 60-80 mesh sorbent.

5.3.2 Removing / replacing a cold trap

The carrier gas supply and

compressed air to the

instrument and the instrument itself

must be turned off before starting.

See video tutorials for animated cold trap removal



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Remove the front top cover from

UNITY 2

1. Pull the cover back

2. Lift up

Loosen the steel fitting attached to the

cold trap

Keep a firm hold of the trap

pneumatics assembly during these

steps – if it is allowed to twist it can

snap the cold trap.

1. Loosen screw by ~4 turns. Do not

remove the screw completely.

2. Gently pull the desorb pneumatic

assembly towards the front of the

instrument being careful to keep it in

the horizontal plane.

Move the assembly clear of the cold

trap.

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Loosen the steel fitting attached to the

1.

2.

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Once clear of the screw, pull the

pneumatics forward and rotate to the

left thus providing sufficient space to

remove the cold trap.

Grip the glass flange and remove the

cold trap by gently pulling (a rubber

laboratory glove will provide a better

grip).

DO NOT APPLY EXCESSIVE

FORCE TO THE QUARTZ COLD TRAP

TUBE.

Most difficult with a cold system - can

switch the unit back on to warm up

before switching off again and

reattempting to withdraw the trap.

Remove the new packed cold trap

from its packaging.

Gently push the trap tube into the cold

trap box.

DO NOT APPLY EXCESSIVE

FORCE TO THE QUARTZ COLD TRAP

TUBE.

If in doubt practice with the trap

alignment tool supplied in the shipping

kit.

NEVER SWITCH UNITY 2 ON

WITH THE TRAP ALIGNMENT

TOOL INSTALLED.

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pneumatics forward and rotate to the

can

Gently push the trap tube into the cold

alignment tool supplied in the shipping

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You will feel increased resistance as

the cold trap pushes into the seal at

the valve end.

Once the trap is properly inserted the

glass flange should be approximately

1 mm from the black plate

Keep a firm hold of the trap

pneumatics assembly during these

steps – if it is allowed to twist it can

snap the cold trap.

Bring the pneumatic assembly back

and relocate the screw in the slot.

Push the assembly gently back in the

horizontal plane guided by the screw.

THE CONNECTOR CAN SNAP

THE END OF THE QUARTZ COLD

TRAP

Apply gentle steady pressure to push

the trap into the sealing O-ring located

inside the steel trap connector.

Retighten the screw firmly

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Gently tighten the steel fitting

attached to the cold trap until slight

resistance is felt

Refit the front cover

Turn on the carrier gas, compressed

gas and instrument power.

Restart the software.

Leak test around the cold trap with a

helium leak detector.



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5.3.3 Removing / replacing a broken cold trap

The carrier gas supply and compressed air to

the instrument and the instrument itself must

be turned off before starting.

Remove the visible end of the cold trap using the

method described in Section 3.2

Unscrew the 2 screws securing the front panel.

Remove the front panel.

Slide the side panels towards the front of

instrument then lift away to remove.

Remove the air lines that supply the heated valve by

pulling the white tube while pressing the black lip of

the connector.

Remove the split tube and any sample tubes /

interconnects.

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Removing / replacing a broken cold trap

The carrier gas supply and compressed air to

instrument itself must

Remove the visible end of the cold trap using the

Unscrew the 2 screws securing the front panel.

Slide the side panels towards the front of the

Remove the air lines that supply the heated valve by

pulling the white tube while pressing the black lip of

Remove the split tube and any sample tubes /

1. 2.

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3.

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Disconnect the thermocouple and heater wire

connectors

1. Loosen the 4 screws highlighted

2. Slide the whole assembly back to allow access to

the brass connector and hold in position by

tightening one of the rear screws.

2.

1.

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Using a 7/16 ” spanner loosen the brass connector

and remove the broken trap with an appropriate tool

If the brass connector needs to be removed, to

access the broken trap, then replace it before

continuing.

1. Feed the trap alignment tool through the cold

trap box to ensure any broken glass is removed.

2. Loosen the screw holding the heated valve

assembly in place and slide forwards again.

3. Retighten the 4 screws.

4. Reattach the thermocouple and heater

connectors.

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1. Place the trap alignment tool into the cold trap

box.

2. The tool should pass smoothly up to the o-ring in

the heated valve before further gentle pressure

moves the tool another 1-2 mm.

If the tool does not move smoothly past the

point where it enters the brass connector

there may be a misalignment problem.

Loosen the 4 screws again and ensure the assembly

is pushed up against the cold trap box.

Reinstall a new cold trap as shown in Section 4.2

1-2 mm 2.

1.



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Turn on the carrier gas, compressed gas and

instrument power.

Restart the software.

In the leak test dialog box select SV4 and HV

Leak test around the brass connector with a helium

leak detector.

If a leak is detected, gently tighten the brass

connector 1/8 turn with a 7/16” spanner and check

for leaks again. Repeat until no leak is detected.

DO NOT OVERTIGHTEN OR YOU RISK

BREAKING THE COLD TRAP AGAIN.

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carrier gas, compressed gas and

In the leak test dialog box select SV4 and HV

Leak test around the brass connector with a helium

ently tighten the brass

n with a 7/16” spanner and check

for leaks again. Repeat until no leak is detected.

DO NOT OVERTIGHTEN OR YOU RISK

BREAKING THE COLD TRAP AGAIN.

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Changing the cold trap seals and filters

The user may change the cold trap O-ring seal on the pneumatic assembly if the cold trap has been

broken and damaged the seal.

To change the seal remove the pneumatic

assembly taking care not to damage the cold

trap (see Section 3.2)

Loosen the thread on the steel connector and

remove the cap

Replace the O-ring (U-COV06).

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6. Trademarks

UNITY 2™, ULTRA™, ULTRA 50:50™, Air Server™ and SecureTD-Q™ are all trademarks of Markes

International Ltd., UK

Windows® is a registered trademark of Microsoft Corporation, USA.

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