2-Inlets.pdf

7/29/2019 2-Inlets.pdf

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Inlets


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In This Section, You Will Learn:

Identifying the Types of Inlets

Identifying the Components in the Packed and Split Inlets

Understanding the Flow Dynamics of the Split Inlet

Calculating Split Ratio

Identifying preventative Maintenance and Troubleshooting


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Inlet Systems

Purpose: To allow the insertion of a sample into the gas

chromatograph in a repeatable, reproducible manner.

The sample should be representative of the bulk, and

unless specifically desired should be inserted without

chemical change.

EPC onlyVolatiles Interface

EPC onlyProgrammed Temperature Vaporization

EPC onlyCool on-columnEPC and non-EPCPurged Pack

EPC and non-EPCSplit/Splitless

Gas ControlInlet Type


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Flow System: Purged Packed Inlet

Flow controlled mode (recommended for packed columns)

Pressure controlled mode (recommended for capillary columns)


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Exploded View of Purged Packed Inlet

Insulation

Insulation cup

Ferrule

Column nut

Insulation

Septum nut

Knurled nutHeater/sensor assembly

SeptumO-ring

PurgedPackedInlet body

Insulation


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Liners/Adapters

Inlet Fitting

1/4-Inch Ferrule

1/4-Inch Nut

1/8-Inch Liner

Front Ferrule

Back Ferrule

1/8-Inch Nut

1/8-InchColumn

Using Two Wrenches in Opposition

to Tighten Column Fittings

1/4-Inch MetalFerrule

Back Ferrule

1/4-Inch Nut

1/4-Inch Column

Inlet Fitting

1/4-Inch Metal Column, 1/8-Inch Metal Column,

Packed InletPacked Inlet

There are a variety of liners

and adapters for different

columns, inlets and detectors.


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Split/Splitless Inlet

Split Mode forPulsed Split

Splitless Mode forPulsed Splitless

Major Component AnalysesAllows for larger injection volume.

Trace Component AnalysesAllows for larger injection volume


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Split/Splitless Flow System


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Split Flow Diagram: Pre-Injection

SEAL

(INLET)

(SEPTUM)

SPLIT VENT

TOTAL FLOW

COLUMN

SEPTUM

CARRIER GAS

LINER

50 mL/min

2 mL/min

0.6 mL/min

48 mL/min

47.4 mL/min

PURGE VENT

PURGE VALVE


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Split Flow Diagram: Sample Injection

(INLET)

(SEPTUM)

SPLIT VENT

TOTAL FLOW

COLUMN

= CARRIER GAS

PURGE VALVE

PURGE VENT

SPLIT RATIO = COLUMN + SPLIT VENT FLOW

COLUMN FLOW

= LIQUID SAMPLE MOLECULES


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Split Flow Diagram: Sample Vaporization

COLUMN

(INLET)

(SEPTUM)

SPLIT VENT

TOTAL FLOW

= CARRIER GAS

= SAMPLE MOLECULES

= SOLVENT MOLECULES

PURGE VENT

PURGE VALVE

Vaporization takes place whensufficient thermal energy istransferred to the sample. Thiscan occur in the carrier gas, but

is more likely upon contact witha solid surface, such as the lineror mixing medium.


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Split Flow Diagram: Sample/Carrier Mixing

(INLET) PURGE VALVE

(SEPTUM)PURGE VENT

SPLIT VENT

TOTAL

FLOW

COLUMN

= CARRIER GAS

= SAMPLE MOLECULES

= SOLVENT MOLECULES

For the concept of SPLIT RATIO tobe valid, the sample (solvent +analyte) must be mixed with thecarrier gas to give a homogeneousmixture.

At the bottom of the injection port a

small part of this mixture will transferto the column, while the bulk of themixture will leave the chromatographvia the SPLIT VENT.


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Split Flow Diagram: Liner Overload

(INLET)

PURGEVALVE

(SEPTUM)

PURGE VENT

SPLIT VENT

TOTAL FLOW

COLUMN

= CARRIER GAS= SAMPLE MOLECULES

= SOLVENT MOLECULES

A large injection of a solvent with alarge expansion volume can causean overload of the injection portliner.

This can result in loss of sample out

the PURGE VENT as well ascontamination of the in-comingcarrier gas line.


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Split Ratio Calculations

Split Ratio = Split Vent Flow + Column Flow

Column Flow

Split Vent Flow = (Split Ratio)(Column Flow) - Column Flow

33:1952.03.0100530

98:1972.01.0100320

196:197.52.00.5100200

SplitRatioSplit Flow

Septum

Purge

Column

FlowTotal Flow

Column

I.D. (m)

DCBA


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Gas Saver

Gas Saver reduces the carrier gas flow from the split vent after thesample is on the column.

Column head pressure and the column flow rate are maintained,while the purge/split vent flows decreases. Can be used in split and splitless modes. Gas Saver time is set to activate during the run after the sample is

on the column.

Split vent

flow(mL/min)

200 -175 -150 -

100 -75 -50 -25 -

-2 -1 0 1 2 3 4 5 6 7 8 9 10

Prep Run Time

Gas Saver

Flow

StartGas saver time set to 2.5 min.

Run ends

Gas saver flow

RegularFlow


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Splitless Flow Diagram

Purge valve closed during injection (no split vent flow). At a specified time after injection, the purge valve opens to sweep remaining

vapors out of inlet.


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Split/Splitless Capillary Inlet Exploded View

Insert Assembly

Liner

Insulation

Washer

Reducing Nut

Insulation

Ferrule

Column Nut

Septum retainernut

Septum

O-ring

Split vent line

Split/splitlessinlet body

Retaining nut

Inlet base seal

Insulation cup


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Ferrule:

GRAPHITE: Good seal easilyVESPEL: Excellent seal - hard

GRAPHITE/VESPEL: Very good seal

with some difficulty

Column Nut: 5181 - 8830

5020 - 8292 Finger-tight

5020 - 8293 530 um Finger-tight

19258-20920 spring loaded -Vespel

Seal: 18740 - 20885, new with 2 slits 5182-9652

Septum: 5182 - 0739

High-temperature

11 mm DIAMETER

Liner Seal:

Viton: 5180 - 4182

Graphite: 5180 - 41685180 - 4173

BELOW 300 C

SPLIT LINER ABOVE 300 CSPLITLESS LINER ABOVE 300 C

3 - 6 mm

APPLICATION

DEPENDENT

GOLD PLATED, STAINLESS STEEL MUST BE KEPTCLEAN CAN BE DEACTIVATED

Washer obsolete

CHANGE WITH LINER

Capillary Injection Port Consumables


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Most Commonly Used Liners

#See the HP Analytical Columns and Supplies Catalog for the complete list of liners.

4-mm id 1000-ul nominalvolume, borosilicateglass (untreated)

silanized glass wool plug

Split and splitless modes,especially recommended forrapid injections with the 7673

Automatic Sampler

19251-60540Split/Splitless

Liners: Untreated

Configuration Recommended Use Part No.Type

4-mm id, nominal volume900 ul, boroscilicate

glass (deactivated),silanized glass wool plug(deactivated)

Split and splitlessmodes.

Can be self-packed.

5062-3587Packed, tapered

Liners: Deactivated

4-mm id, nominalvolume 900 ul,boroscilicate glass(deactivated)

5181-3316Unpacked, tapered Split and splitlessmodes.Can be self-packed.

!!New Deactivated Split Liner!! 5183-4647


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Capillary Liner Maintenance

General Purpose, Non-Deactivated LinersCLEANING PROCEDURE:1. Remove glass wool

2. Sonicate in solvent or acid bath3. Rinse & dry4. Replace deactivated glass wool5. Deactivate Silylate*

6. Dry*Silanizing agents available from column suppliers.

Factory Deactivated (Pesticide Liners)CLEANING PROCEDURE:1. Remove glass wool2. Sonicate in solvent(s)3. Dry4. Care should be taken to avoid scratching the inner surface of the liner.

#TREAT AS ULTRA CLEAN PART


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Injection Port Seal: Maintenance

Sonicate in Solvent Bake Dry

Deactivate with Non-Chlorinated Reagent HMDS BSTFA BSA

TSIM Wash with Solvents

Inert First Wash - Toluene Alcohol Second Wash - Methanol

Bake Dry

#TREAT AS ULTRA CLEAN PART


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Injection Port Problems

Non-Representative sample Incorrect Temperature

Blockage Contamination Leaks

Detecting Leaks Snoop Electronic Leak Detector Pressure test Chromatographic Changes (compare shifts in retention time

and area counts)


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Injection Port Maintenance

Change the septum regularly.

Use the lowest practical temperature.

Purge with flow. Use clean liners.

Solvent clean the seal.

Use clean syringes.


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Other Inlets

Programmed Temperature Vaporization Inlet:

Large Volume Injection (LVI) with PTV for trace analysis of

later eluting solutes and dirty samples. Multiple injections are made in a cool inlet and then the

temperature is ramped.

Inlet uses Septum-less head.

Volatiles Interface:

Introduce a gas sample from an external device such as the

headspace, purge and trap, or air toxics samplers.

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