The Use of Eluent Generation in Ion Chromatography

Mi h l G H i dMichael G. Hvizd2014 Eastern Analytical Symposium

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Eluent Preparation in Ion Chromatography

M ll (Si l C t ti )• Manually (Single Concentration)• Weigh reagents• Dilute in water• Prone to inconsistencies and contamination

• Dilution (Single Concentration)• Aliquot of a stock solution (manually or automatic)• Dilute in water• Prone to inconsistencies and contaminationProne to inconsistencies and contamination

• Electrolytically Generated (Variable Concentrations)• “Just Add Water”• Consistent (day to day, week to week, operator to operator)• Contamination free• Gradient capable

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Gradient capable

What is Eluent Generation

• In Eluent Generation, an Eluent Generator (EG) is used to electrolytically generate clean, pure mobile phases for anion or cation separationsanion or cation separations

• Since the process is electrolytic and is controlled by a power supply, it creates very pure, contamination-free eluentseluents

• Eluent concentration is proportional to the applied current and flow rate

• The subsequent analysis is very reproducible and can run for months

• It is important to note that this is not “eluent dilution”It is important to note that this is not eluent dilution• Eluent Generation is one component of the Reagent-Free™

Ion Chromatography (RFIC-EG) system

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RFIC System Components

• RFIC systems are ion chromatography systems that utilize electrolysis and/or electrolytic devices to generate eluents in the separation processes and produce regenerant ions in thethe separation processes and produce regenerant ions in the suppression process• Thermo Scientific™ Dionex™ Eluent Generation (EGC) Cartridge• Continuously Regenerated Trap Columns

• Thermo Scientific™ Dionex™ CR-ATC Continuously Regenerated Anion Trap Column

• Thermo Scientific™ Dionex™ CR-CTC Continuously Regenerated Cation Trap Column

• Continuously Regenerated Suppressors• Thermo Scientific™ Dionex™ AES™ Atlas™ Electrolytic Suppressor• Thermo Scientific™ Dionex™ CES™ Capillary Electrolytic Suppressor

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RFIC-EG System Schematic

Waste

PumpElectrolytic

EluentH O Gas Removal Pump Eluent Generator

H2O Device

InjectorSeparationColumn

ConductivityDetector

ElectrolyticSuppressor Column

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Electrolytic Generation of KOH Eluents

Pt anode CurrentPt anode

(H2O 2H+ + ½O2 + 2e–)K+

ElectrolyteReservoir

[KOH] Current

Flow rateVent

Cation-ExchangeConnector

HydroxideGeneration ChamberPump

Reservoir

K+

HC a bep

H2OKOH + H2

KOH

H2

DegasUnit

Pt Cathode(2H2O + 2e– 2OH– + H2)

Dionex CR-ATCColumn

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Electrolytic Generation of Methanesulfonic Acid (MSA)

VentPt Cathode [MSA]Current

Fl R t

Anion-

Vent

(2H2O +2e– 2OH– + H2)

[MSA] Flow Rate

MSA-

ElectrolyteReservoir Anion

ExchangeConnectorMSA

Generation ChamberPump

MSA-

O2

H2O

Pt A d

MSA + O2MSA

Dionex CR-CTCColumn

Degas Unit

Pt Anode(H2O 2H+ + ½O2 + 2e–)

Column

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Improved Performance for Trace Anion Analysis

Column: Thermo Scientific™ Dionex™ IonPac™ AG11/AS11 (2 mm)

Eluent: (A) NaOH(B) KOH (Di EGC KOH t id th )

1.20(A) Conventional 119

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using a Thermo Scientific™ Dionex™ EGC KOH Eluent Generator Cartridge

(B) KOH (Dionex EGC-KOH cartridge as the source)0.5 mM to 2.5 min, to 5.0 mM at 6 min,to 26 mM at 20 min

Flow Rate: 0.5 mL/minInj. Volume: 1.0 mLSuppressor: Thermo Scientific™ Dionex™ ASRS™ Suppressor,

external water mode

µS

( )Gradient* 10

765

43

21

external water modeDetection: Suppressed conductivity

Peaks: 1. Fluoride 0.37 µg/L (ppb)2. Acetate 1.03. Formate 0.934. Chloride 0.445 Nit it 0 27

1.20

08

µS

5. Nitrite 0.276. Bromide 1.07. Nitrate 0.338. Carbonate –9. Sulfate 0.64

10. Oxalate 0.3911 Phosphate 1 1

(B) EG Gradient

1110

91

23 4

56

7

Minutes0 5 10 15 20

0

11. Phosphate 1.111103 6

* Baseline increase due to carbonate impurity

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Minutes

Reproducibility of an RFIC-EG Anion SystemColumn: Dionex IonPac AS18 4 mmColumn: Dionex IonPac AS18, 4 mmEluent Source: Dionex EGC-KOH Eluent Generator Cartridge with a Dionex CR-ATC ColumnEluent: 22–30 mM KOH: 7–8 minFlow Rate: 1.0 mL/minTemperature: 30 °C

Overlay of 20 consecutive runsRetention time RSD: 0 012% (NO ) t 0 035% (PO 3 ) Inj. Volume: 25 µL

Suppressor: Thermo Scientific™ Dionex™ ASRS™ ULTRA II Anion Self-Regenerating Suppressor at 100 mA

Detection: Suppressed conductivity

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2

39

0.012% (NO3–) to 0.035% (PO4

3–)

Sample: Anion StandardPeaks: 1. Fluoride 2.0 mg/L

2. Acetate 103. Formate 104. Chlorite 105 Chl id 3 0

4µS1

2

4

5

10

5. Chloride 3.06. Nitrite 107. Carbonate —8. Bromide 109. Sulfate 15

10 Nitrate 10

6

7

811

1210. Nitrate 1011. Chlorate 1012. Phosphate 1510 20 300

Minutes

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Separation of Anticorrosion Amines and Cations Using a RFIC-EG System

3.00

5

16 17

55 mM

Column: Dionex IonPac CG16/CS16, 3250 mmEluent: MSA (EGC gradient)Temperature: 60 °CFlow Rate: 0.5 mL/minInj. Volume: 10 µLD t ti S d d ti it

1 2

34

58

Detection: Suppressed conductivity,Thermo Scientific™ Dionex™ CSRS™ ULTRA II Cation Self-Regenerating Suppressor, recycle mode

Peaks:1. Lithium 0.5 ppm

67

9

1112

14

15µS

2. Sodium 23. Ammonium 2.54. Monoethanolamine 15. Methylamine 0.56. Diethanolamine 17 Eth l i 1 511

1315

10

7. Ethylamine 1.58. Potassium 59. Dimethylamine 110. Triethanolamine 111. Methyldiethanolamine 112 Dimethylethanolamine 1

10 20 30 40 500.20

Concentration: 6 mM

Minutes

12. Dimethylethanolamine 113. Morpholine 514. 1-Methoxypropylamine 115. Dimethylamino-2-propanol 116. Magnesium 2.517. Calcium 5

10

Minutes

Common Cations on a 2 mm Dionex IonPac CS12A Column

Column: Dionex IonPac CG12A/CS1S12A, 2250 mmEluent Source: Dionex EGC II MSA cartridgeEluent: 20 mM MSA Temperature: 30 °CFl R t 0 25 L/ i

5.0

4

Flow Rate: 0.25 mL/minInj. Volume: 5 µLDetection: Suppressed conductivity,

Dionex CSRS ULTRA II Suppressor, recycle modePeaks:

µS1

2 3 5 6 1. Lithium 1.0 mg/L2. Sodium 4.03. Ammonium 5.04. Potassium 105. Magnesium 5.06. Calcium 10

Overlay of 30 consecutive runsRetention time RSD:

0.0 16.0-0.5

Minutes

Retention time RSD: 0.043% (Li+) to 0.051% (K+)Peak area RSD:0.09% (Ca2+) to 0.12% (K+)

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Eluent Generator Cartridge Specifications

• Dionex EGC 500 KOH Eluent Generator Cartridge• 0.1 to 100 mM (Capillary 0.1 to 200 mM)• 5000 psi max pressure• 5000 psi max pressure• Up to 25% methanol

• Dionex EGC 500 MSA Eluent Generator Cartridge• 0.1 to 100 mM (Capillary 0.1 to 200 mM)• 5000 psi max pressure• No solvents• No solvents

• Dionex EGC 500 K2CO3 Eluent Generator Cartridge• 0.1 to 15 mM• 5000 psi max pressure• No solvents

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Benefits of RFIC-EG Systems

• Use Dionex 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• Improve retention time reproducibility for both isocratic and gradient separations

• Compatible with a wide range of high-performance detection th d i l di d ti it UV Vi l t h i l dmethods 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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Simplify system operation and reduce overall operating cost

Thank you!

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OT71427-EN 1114S