Continual Innovation and Achievement: 40 Years of Ion ... · Reagent-Free Ion Chromatography (RFIC)...
Transcript of Continual Innovation and Achievement: 40 Years of Ion ... · Reagent-Free Ion Chromatography (RFIC)...
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The world leader in serving science
25th Annual Good Laboratory Practice Conference
Virginia AWWA / VWEA
Laboratory Practice Committee
Buddy Goodnight
NA COE IC Support Specialist
Continual Innovation and Achievement: 40 Years of Ion Chromatography
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Agenda
• Define Ion Chromatography
• History of Ion Chromatography
• Typical IC Configuration
• Markets
• Role of Chemical Eluent Suppression
• Typical Applications
• (Reagent Free Ion Chromatography) Technology
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Ion Chromatography
Ion Chromatography is an analytical technique that
utilizes ion exchange mechanisms to separate ionic
substances followed by detection utilizing conductivity,
amperometry, UV/Vis, fluorescence, and mass
spectrometry.
Analyte classes include:
Anions
Cations
Organic Acids
Amines
Transition Metals
Carbohydrates & Amino Acids
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Definitions http://en.wikipedia.org/wiki/Ion
• Ion chromatography (or ion-exchange chromatography) is a process
that allows the separation of ions (or ionizable) and polar molecules
based on the charge properties of the molecules. It can be used for
almost any kind of charged molecule including carboxylic acids,
amines, large proteins, carbohydrates, small nucleotides and amino
acids.
• The solution to be injected is usually called a sample, and the
individually separated components are called analytes. It is often used
in water analysis, quality control, and protein purification.
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Definitions
• Mobile phase or eluent
• The phase that travels through the column
• Typically a liquid
• Its purpose is to transport the analytes and permit interaction with the
stationary phase
• Stationary phase or Column
• Generally an inert solid or gel to which various functional groups are
attached
• The stationary phase interacts with the compounds being analyzed and
slows their passage through the column
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• Limited automated instrumentation
• Most ion analysis was colorimetric, turbidimetic or ISE
• Ion-exchange resins were used but only as a sample prep tool
for wet chemical analysis methods
• Data handling: Do you remember “chart recorders” and “integrators”?
• Reports: Typed with carbon paper on an electric typewriter and mailed with
a stamp
Disadvantages of Wet Chemistry Methods
• Large matrix effects, color interference, low sensitivity,
labor intensive
Chromatography Goal: Water as a mobile phase
• Tried and discarded
The Landscape Before Ion Chromatography
Ionic analysis was a desert, a wet desert
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Essential Elements of an Ion Chromatography System
IC was a disruptive technology.
What was missing for today’s IC?
• Manufacturing process for ion-exchange stationary phases
• Suitable mobile phase
• Aqueous solutions had electrical conductance due to high ionic content
• Device to strip ionic content from the mobile phase
• Low electrical conductance. Water is the perfect background (goal)
• Detector for analytes that do not have chromophores
• A conductivity cell for conductivity detection
• Instrument to run the separation and detection methods
• “Integrator” or method to process or present the data
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• Defined “ion chromatography”
exclusively as a combination of
1) Ion-exchange separation
2) Eluent suppression
3) Electrical conductance detection
Fathers of Ion Chromatography
• Hamish Small, Bill Bauman and Tim Stevens
(Dow Chemical)
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The Very First Ion Chromatograph – Dow Chemical
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Cations Came First: 26 min for Three Cations!
• 10 mM lithium, sodium, and potassium
as chloride salts
• Only monovalent cations
• Column: a lightly sulfonated
styrene–divinylbenzene (DVB) polymer, 50 µm
• Eluent: 20 mM HCl
• Injection Vol.: 100 µL
• Dowex 1 “Stripper” (suppressor): (hydroxide form)
Hamish laboratory notebook,
November 9, 1971
Hamish Small, LCGC April 02, 2013
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In 1975, Established the Foundations of IC
• Licensing agreements: Dow Chemical and Durrum Instruments
• Durrum/Dow ION EXchange = DIONEX
• Formation of one company
– Dionex Corporation (1978)
• Column Process: Surface-sulfonated
styrene–DVB resin with a suspension of a
colloidal anion-exchange resin
• Eluent system: Carbonate based buffers
• Suppressor: Switching packed bed
• Detector: Suppressed conductivity
• First commercial IC: Dionex Model 10
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Sample Inject
(Autosampler)
Eluent
Non-
Metallic
High-
Pressure
Pump
Separation Detection
Data
Management
Ion-Exchange
Analytical Column
Eluent
Suppressor
Conductivity
Detector
Principles of Ion Chromatography
Main Menu
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Ion Chromatography answers a Wide Diversity of Application Areas and the Markets it Supports
• Environmental
• Chemical & Petrochemical
• Pharmaceutical & Biotechnology
• Power & Energy Production
• Electronics, Semiconductors & Plating
• Pulp & Paper
• Foods & Beverages
• Personal Care & Household Products
• Agricultural Products
• Forensics
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Typical Ion Chromatographic System - Anion Analysis
Eluent Bottle (CO3/HCO3 or NaOH)
Pump
Guard Column
Analytical Column
Suppressor
Regen In (H2SO4)
Conductivity Cell
Chromatography Software Ion
Exchange Separation
Post-
Suppression Conductivity
Data Handling and Instrument Control
Sample Injection
Regen Out (H2SO4)
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Chemical Suppression
Analytical Column (Anion
Exchanger )
Anion Suppress
or (Cation
Exchanger)
HF, HCI, H2SO4 in H2CO3
NaF, NaCI, Na2SO4 in Na2CO3
Waste
H+
Eluent (Na2CO3)
Sample F–, CI–, SO4
2–
F–
SO42
– CI –
Time
µS
With Suppression
H2CO3
Without Suppression Counterions
µS
Time
F–
SO42
– CI–
Na2CO3 Background
Main Menu
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1980s: Developing Continuous Suppression
• Switching packed bed suppressors required periodic regeneration
• Disadvantages: defined capacity (4 to 8 hr)
• Periodically replace with another suppressor or
• Wait while suppressor was being regenerated off line
• Led to development of continuous tubular suppressor (Tim Stevens –
Dow; Sandy Dasgupta –Texas Tech)
• In 1985 Dionex Corp. introduced flat membrane continuous suppressor,
the MicroMembrane Suppressor (MMS)
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Suppressor Innovations Inspire Column Innovations
• Goal: NaOH as anion eluent because it suppresses to water
Efficient suppressors to neutralize high concentrations of strong base
• Thermo Scientific™ Dionex™ MMS™ MicroMembrane suppressor has sufficient
suppression capacity
Sparking Column Innovations
• Optimized polymer branching in stationary phases to include hydroxide
selectivity
• Result: increased selectivity, more control over resolution
• Launched with the introduction of Dionex IonPac AS5A column in 1985
Chris Pohl: Stationary Phases and Suppressors in Ion Chromatography, 1975-2000
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Selection of Eluent Driven by Column Innovations
• Goal: NaOH as anion eluent because it suppresses to water
• Limitations
• Hydroxide has low affinity for 1970’s anion-exchange columns
• Columns require high eluent concentrations to elute analytes
• High hydroxide concentrations strain the suppressor capacity
• Compromise: Carbonate eluents
• Converts to weak and low conducting carbonic acid
• Compatible with the early suppressors
• Issue: the baseline conductivity is ~10–22 µSiemens
• Eluent family for more than 20 yrs
circa 1974
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1990’s: Fixing Carbonate Eluent Limitations
• Conductivity is 10–20x higher than pure water which impacts sensitivity
• Nonlinear responses at lower analyte levels
• Gradient separations were difficult
• Ramping
• Baseline disturbances
• Slow buffering
Solution: Hydroxide based eluent
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Hamish Small et al.
Publish First IC paper
Switching Packed Bed Suppressor
Fiber suppressor (continuous suppression)
Micromembrane suppressor
(high capacity continuous
suppression) I
Cation Suppression Introduced
Self-regenerating micromembrane
suppressor (electrolytic
regeneration)
1975 1981
1985
1992 1978
2007
Thermo
Scientific™
Dionex™
SRS™ 300
Suppressor
Continuous development to extend lifetime,
pressure range, and robustness
2010
Cap IC
Thermo
Scientific™
Dionex™ CES™
300 Suppressor
2013
Thermo
Scientific™
Dionex™ CRS™
500 Suppressor
Suppressor Development
Thermo
Scientific™
Dionex™ ERS™
500 Suppressor
2015
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Altering Selectivity in Ion Chromatography
Mobile phase parameters
• Eluent Ion
• Eluent concentration
• Eluent pH
• Organic additives
• Temperature
Mainly retention changes Little control on selectivity
Better control of selectivity
Stationary phase parameters
• Material
• Functional group
• Capacity
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Supermacroporous
(SMP) Microporous
Resin Technology
• Resin: polystyrene-divinylbenzene
• Bead type: microporous, macroporous, supermacroporous
• Size: down to 4 µm i.d.
Hyperbranched Polymer
Grafting
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Pellicular Anion-Exchange Bead (Latex)
SO– 3
SO– 3
SO– 3
SO– 3
SO– 3
SO– 3
0.1-mm Diameter Latex Core Ion-Exchange
Surface
R3N+
R3N+
N+R3
N+R3
N+R3
R3N+
R3N+
N+R3
N+R3
R3N+
R3N+
N+R3
N+R3
R3N+
R3N+
N+R3
N+R3
SO–3
3183-03
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Latex Agglomerated Supermacroporous Resin
Anion Exchange Latex Coating
65-nm Diameter Microbeads
Ethylvinylbenzene-Divinylbenzene Core
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+
Cl–
Cl–
Cl–
Cl–
Positively
Charged
Polymeric
Particle
Anion Exchange Mechanism
Stationary Phase
OH– < BO3– < HCO3
– << CO32–
+
+
+
+
+
+ +
Mobile Phase
Cl–
Eluent
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Ion-Exchange Chromatography Principles
Ion separation is determined by the analytes different
affinities towards the stationary phase.
----> High affinity for the functional group results in longer retention
Ion properties determining retention:
● Ion’s charge: single charge = weak retention, double charge = strong retention
● Ion’s size: large solvated ion = shielded charge = weak retention
● Ion’s polarizability (hydrophobicity): no or poor solvation = very strong retention
General isocratic elution order for anions:
F– Cl– Br– NO3– HPO4
2– SO42–
For cations:
Li+ Na+ NH4+ K+ Mg2+ Ca2+ Sr2+ Ba2+
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Total Conductivity (Σ ) Detection
Σ = λanion + λcation
where λ = equivalent conductance
Anions Cations
OH- 198 H+ 350
F- 54 Li+ 39
Cl- 76 Na+ 50
NO3- 71 K+ 74
Acetate- 41 CH3NH3+ 58
Benzoate- 32 N(CH3CH2)4+ 33
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1° Amines
R-NH2
2° Amines
R’
R-N-H
4° Amines R4N
+
Functional Groups Detected with Suppressed Conductivity
3° Amines
R’
R-N-R”
Suppressed Conductivity Detection
Inorganic Anions
e.g., F_,
CI_,
NO2
_,
NO3
_,
SO42_
,
PO43_
, I_,
Br
_, CIO3
_,
SCN
_,
S2 O3 2_
Inorganic Cations
Alkali Metals:
Li+, Na+, K+,
Rb+, Cs+,
Alkaline Earths:
Mg2+, Ca2+
Sr2+, Ba2+ ,
Ammonia:
NH4+
Phosphates
O
R-O-P-OH
OH
Sulfates
R-O-S-OH
O
O
Sulfonates
R-S-OH
O
O
Phosphonates
R-P-OH
O
OH
Carboxylics
R-C-OH
O
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Column: IonPac™AG4A-SC/AS4A-SC Eluent: 1.7 mM Sodium bicarbonate/ 1.8 mM sodium carbonate Flow Rate: 2.0 mL/min Injection: 50 µL Detection: Suppressed conductivity, ASRS™ ULTRA Anion Self Regenerating Suppressor, recycle mode
Peaks: 1. Fluoride 2 mg/L 2. Chloride 3 3. Nitrite 5 4. Bromide 10 5. Nitrate 10 6. Phosphate 15 7. Sulfate 15
0 2 4 6 8
Minutes
0
µS
10
10
1
2 3 4 5
6
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IC Written into U.S. EPA Method 300.0 (A) (Drinking Water Analysis)
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Column: IonPac® AG14A, AS14A, 5µm, 3 x 150 mm
Eluent: 8.0 mM sodium carbonate 1.0 mM sodium bicarbonate
Flow Rate: 0.8 mL/min
Temperature: 30 °C
Inj. Volume: 5 µL
Detection: Suppressed conductivity,
ASRS® ULTRA II, 2 mm, AutoSuppression® recycle mode
Peaks: 1. Fluoride 5 mg/L (ppm) 2. Acetate 20 3. Chloride 10 4. Nitrite 15 5. Bromide 25 6. Nitrate 25 7. Phosphate 40 8. Sulfate 30
Isocratic Anion Separation EPA 300.0
0 1 2 3 4 5 6
Minutes
0
12
1 3
4 5
7
2
µS
6 8
15907
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Reagent-Free Ion Chromatography (RFIC) Systems
● RFIC™ systems are ion chromatography systems
that utilize electrolysis and/or electrolytic devices
to generate (EG) or regenerate (ER) eluents in
the separation processes and produce
regenerant ions in the suppression process.
●RFIC-EG™ systems (2003)
●RFIC-ER™ systems (2008)
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Electrolytic Eluent Generation and Suppression
Eluent
Generation
(KOH)
Anion Suppressor
Anion Column
HF, HCI, H2SO4 in H2O
KF, KCl, K2SO4 in KOH
Waste
Time
µS
With Suppression
Waste H+
K+
F–, CI–, SO42 –
F–
CI– SO42–
Sample
H2O
Detector
Without Suppression
Counterions
µS
Time
F– CI– SO42 –
KOH
Main Menu
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Essential Elements of RFIC
Electrolytic functions built on the simple electrolysis of water
• Electrolytic eluent generation and purification
• Electrolytic suppression of eluents
“Just Add Water”
Cathode 2e– + 2H2O 2OH– + H2 (g)
Anode H2O 2 H+ + ½ O2 (g) + 2e– + OXIDATION
REDUCTION -
RFIC = Reagent-Free Ion Chromatography
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Benefits of RFIC-EG™ Systems
• Use EGC cartridges to generate high purity acid, base, or carbonate eluents on-line using deionized water as the carrier
• Produce eluents of precise and reproducible concentrations through the convenient control of electrical current
• Improve retention time reproducibility for both isocratic and gradient separations
• Compatible with a wide range of high-performance detection methods including conductivity, UV-Vis, electrochemical, and MS
• Improve the ease of use, sensitivity, and performance of IC methods (day-to-day and lab-to-lab) for the determination of target analytes in a wide variety of sample matrices
• Simplify system operation and reduce overall operating cost
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Separation of Common Anions and Oxyhalides:
(A) IonPac AS9-HC (Isocratic)
0 5 10 15 20 25
0
10
µS
1
2 3
4
5
7
6
8
11
10
Minutes
–1
40
1 2 3
4 5 6 7 8
9
10
11
0 5 10 15 20 25 30
µS
(B) IonPac AS19 (Gradient)
Column: (A) IonPac AG9-HC, AS9-HC (B) IonPac AG19, AS19, 4 mm
Eluent: (A) 9 mM sodium carbonate (B) Potassium hydroxide: 10 mM 0 to 10 min, 10–45 mM 10 to 25 min
Eluent Source: (B) ICS2100 EG with CR-ATC
Temperature: (B) 30 °C
Flow Rate: 1.0 mL/min
Inj. Volume: 25 µL
Detection: ASRS® ULTRA II, 4 mm, recycle mode, 130 mA
Peaks: 1. Fluoride 3 mg/L 2. Chlorite 10 3. Bromate 20 4. Chloride 5 5. Nitrite 15 6. Chlorate 25 7. Bromide 25 8. Nitrate 25 9. Carbonate — 10. Sulfate 30 11. Phosphate 40
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RFIC™ System for Anions Using EPA Method 300.0 (A)
Column: IonPac® AG18, AS18, 4 mm
Eluent: 22–40 mM KOH from 7–8 min
Eluent source: ICS-2000 with CR-ATC
Temperature: 30 °C
Flow rate: 1.0 mL/min
Inj. volume: 25 µL
Detection: ASRS® ULTRA, 4 mm recycle mode, 100 mA
Peaks (A) (B) 1. Fluoride 2 0.07 mg/L (ppm) 2. Chloride 5 45.3 3. Nitrite 10 0.07 4. Carbonate — --- 5. Bromide 20 0.03 6. Sulfate 10 58.7 7. Nitrate 20 2.88 8. Phosphate 30 1.44
Sample: Sunnyvale, CA, drinking water
0 4 8 12 16 0
µS
20
1
2 3
4
5
6 7
8
Standard
Minutes 0 4 8 12 16
0
14
1
2
3 4 5
6
7 8
µS
Municipal Drinking
Water
(A)
(B)
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Eluent
Autosampler
High-Pressure
Nonmetallic
Pump
Thermo Scientific
Dionex
IonPac™ NG1
Thermo Scientific
Dionex
IonPac AS7
Post column
Reagent
System Configuration for Hexavalent Chromium by U.S. EPA Method 218.6
Mixing
Tee
UV-vis
Detector
Knitted Reaction
Coil
Waste
Sample Loop
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Chromate Detection
Column: IonPac AS7 (2 × 50 mm), AS7 (2×250)
Eluent: 250 mM (NH4)2 SO4,
100 mM NH4OH
Flow: 0.36 mL/min
Inj. Vol: 1000 µL
Postcolumn Reagent: 2 mM diphenylcarbazide
10% methanol
1N sulfuric acid
Reaction Coil: 125 µL
Flow Cell: Standard (PEEK), 11 µL
0 1 2 3 4 5 6 7 8 9 10 -0.5
2.5
Minutes
mAU
A. DI water blank
B. 0.005 µg/L Cr(VI) in DI water
B
A
Blank and low-level chromate Comparison of chromate in high ionic-strength
water (HIW) and Sunnyvale tap water
Column: IonPac™AS7 (2 × 50 mm),
AS7 ( 2 × 250 mm)
Eluent: 250 mM (NH4)2 SO4,
100 mM NH4OH
Flow: 0.36 mL/min
Inj. Vol: 1000 µL
Postcolumn Reagent: 2 mM diphenylcarbazide
10% methanol
1N sulfuric acid
Reaction Coil: 125 µL
Flow Cell: Standard (PEEK), 11 µL
A. 0.1 µg/L Cr(VI) in DI water
B. 0.1 µg/L Cr(VI) in HIW
C. 0.1 µg/L Cr(VI) spiked in
Sunnyvale, CA tap water
1 ppt Detection can be achieved!
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• IC is extremely sensitive and can measure down to 1ppt MDL
• Cr(VI) is very stable in most waters
• Holding time in EPA 218.7 is 14 days
• Cr(VI) contamination has been found in chemicals used for eluents and preservation
buffers
• EPA 218.7 allows easier pH adjustment to pH 8.0
• Also uses weaker buffers to prevent column overloading
• Free chlorine will oxidize Cr(III) to Cr(VI)
• Need to minimize impact with NH4SO4 addition to form chloramines
• Chlorine must be <0.1 ppm prior to collection
• Filtering samples is not required
• Preservative is prepared once every 30 days
• Can add preservative to bottles prior to sample addition
• Chilling of samples is not required.
Analytical Issues involving Cr(VI) determination in water
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Maintaining a Healthy IC
• In this workshop session, we will provide tips and tricks to maintain your IC at optimum performance for a more practical, lean, and green operation.
• Four Steps to IC Troubleshooting 1. Identify the symptom
Know your systems vital signs Check for leaks and alarms
2. Identify the consequences 3. Isolate the cause of the problem
Start with the basics Change only one variable at a time Record the changes to the system and the results of the changes
4. Repair the problem
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Know Your System’s Vital Signs
Backpressure
Background
Baseline noise
Retention times
Peak shape
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ICS Components That Impact System Wellness
Eluent
Pump
Injector
Column
Suppressor
Detector
“Keep it Simple”
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M & T: Backpressure
Measured by the pump transducer
Too much backpressure may cause… Not enough backpressure may cause…
Leaks
Damage to components
Noise
Performance problems
Trapped bubbles
Noise
Unstable flowrate
Performance problems
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M & T: Background Conductivity
Symptoms
Background too high Background too low
Eluent too strong
Contaminated eluent
No current
Bad water
Eluent too weak
Wrong eluent
Bad flow cell
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M & T: Retention Times
Possible causes of retention time shift:
Contamination
Incorrect eluent strength
Gradient problem
Inconsistent flowrate
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M & T: Noise
Possible causes for baseline noise:
Small leak
Air
Pump problems
Turbulent flow path
Contaminated eluent
Temperature instability
Faulty electronics
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Pumps—Theory
• Piston
• Draws and expels liquid
• Check valves
• Control direction of flow
• Piston seal
• Allows piston to travel in and out
• Blocks liquid from leaving
• Series pumps
• Only the primary head has check
valves
• Sides collaborate & increase efficiency
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Check Valves
Check valve assemblies have removable
cartridges
Inlet and outlet assemblies are different
Inlet and outlet cartridges are identical
Purpose:
Controls direction of flow
FLOW
Check Valve Cartridge
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Suppressor Troubleshooting
• Alarms
• Spikes
• Increased noise
• High background conductivity
• Leaks
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M & T: Peak Shape
Peak shape variation may be a symptom of a problem
Peak broadening
Peak tailing
Peak fronting
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Tips for Column Care / Cleanup
• Always use a guard column to retain contaminants and protect the analytical column. Replace or clean guard when capacity is 50% from new.
• When unsure of the appropriate column cleaning solution, use 10x to 100x the eluent concentration.
• During column cleanup, place the guard column after the analytical column.
• Place after pressure transducer for minimum contamination.
• Use low flow rate: 0.5 mL/min for 4 mm columns.
• Always pump cleaning solution through the columns in the same direction as the eluent flow.
• Column manuals contain detailed information on operation, maintenance, and troubleshooting.
• Organic contaminants, use solvents; transition metals, use 0.2 M oxalic acid. Wash with deionized water in-between.
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Column Troubleshooting Summary
• Remake eluent
• Check for leaks
• Check if pump is running properly
• Check capacity on guard column
• Remove or replace the guard column; recheck backpressure and
retention time of standard
• Check bed supports for discoloration
• Clean or replace column
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To contact your local Thermo Fisher Scientific Sales Representative
• Central-Eastern Virginia/Eastern NC: Dan Ciminelli
• Washington/DC-Beltway Maryland/North VA: Donna Zwirner
• Charlotte, Greensboro, Fayetteville, and parts of Western NC and
Western Virginia: Samantha Stikeleather
• Your representative will be determined by your company location and
your zip code
• I can be contacted by email: [email protected]
• http://www.thermoscientific.com/dionex
• https://appslab.thermofisher.com/
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The world leader in serving science 54 54
Thank You!
Thank you for your attention!