Ion Chromatography: Green Chemistry for a Green Environment Ken Kirkbride Somerset, New Jersey October 12, 2011

2

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 or mass spectrometry detectors.

Analyte classes include:

Anions

Cations

Organic Acids

Amines

Transition Metals

3

Regulatory Methods that Use Ion Chromatography Chemical or Contaminant ASTM EPA

Method Description

Anions D4327 300.0 9056 The Determination of Inorganic Anions in Water by Ion Chromatography

D4327 300.1 9056

The Determination of Inorganic Anions in Drinking Water by Ion Chromatography

D5794 Standard Guide for Determination of Anions in Cathodic Electro-Coat Permeates by Ion Chromatography

D5827 Test Method for Analysis of Engine Coolant for Chloride and Other Anions by Ion Chromatography

E1787 Standard Test Method for Anions in Caustic Soda and Caustic Potash (Sodium Hydroxide and Potassium Hydroxide) by Ion Chromatography

WK 5500

Standard Test Method for Chloride at Trace Levels in Monoethylene Glycol (Ion Chromatography Method)

E1787 Standard Test Method for Anions in Caustic Soda and Caustic Potash

ISO Method 10304-1

Water Quality—Determination of Dissolved Fluoride, Chloride, Nitrite, Orthophosphate, Bromide, Nitrate and Sulfate Ions, Using Liquid Chromatography of Ions—Part 1 Method for Water with Low Contamination

4

Regulatory Methods that Use Ion Chromatography

Chemical or Contaminant ASTM EPA

Method Description

Bromate 300.1 The Determination of Inorganic Anions in Drinking Water by Ion Chromatography

302.0 2-D Determination of Bromate by Ion Chromatography

317 Determination of Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using Ion Chromatography with the Addition of a Postcolumn Reagent for Trace Bromate Analysis

321.8 Determination of Bromate in Drinking Waters by Ion Chromatography Inductively Coupled Plasma—Mass Spectrometry

326 Determination of Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using Ion Chromatography Incorporating the Addition of Two Postcolumn Reagents for Trace Bromate Analysis

ISO 15061

Water Quality— Determination of Dissolved Bromate— Method by Liquid Chromatography of Ions (ISO 15061:2001); German Version EN ISO 15061:2001

Hexavalent Chromium D5257 218.6

Determination of Dissolved Hexavalent Chromium in Drinking Water, Groundwater, and Industrial Wastewater Effluents by Ion Chromatography. (IC with AS16)

5

Regulatory Methods that Use Ion Chromatography

Chemical or Contaminant ASTM EPA

Method Description

Perchlorate 314 IC with AS16

314.1 Determination of Perchlorate in Drinking Water Using Inline Column Concentration/Matrix Elimination IC with Suppressed Conductivity. (IC with Cryptand Column)

314.2 2-Dimensional IC with the AS20 and AS16 IonPac® Columns and Suppressed Conductivity Detection

331.0 LC-MS/MS Using the IonPac AS21 Column 332.0 IC-MS and IC-MS/MS with the IonPac AS16 and AS20 Columns

WK652 Test Method for Perchlorate in Water by Chemically Suppressed Ion Chromatography

Perchlorate—Solid Waste 6850 Perchlorate in Water, Soils and Solid Wastes Using High-Performance

Liquid Chromatography/Electrospray Ionization/Mass Spectrometry Perchlorate— Solid Waste 6860 Perchlorate in Water, Soils and Solid Wastes Using Ion

Chromatography/Electrospray Ionization/Mass Spectrometry

6

Regulatory Methods that Use Ion Chromatography Chemical or Contaminant ASTM EPA

Method Description

Cations D6910-03 Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium in Water and Wastewater by Ion Chromatography

D6919 Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium in Water and Wastewater by Ion Chromatography

Carbohydrate D5896 Standard Test Method for Carbohydrate Distribution of Cellulosic Materials (Wood Sugars)

Cyanide D6994-04 Standard Test Method for Determination of Metal Cyanide Complexes in Wastewater, Surface Water, Groundwater and Drinking Water using Anion Exchange Chromatography with UV Detection

Haloacetic Acids 557

Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS)

7

EPA 300.0 AND 300.1 Inorganic Anions in Water

8

Columns for Carbonate Methods

Method 300.0, Part A • AS4A, AS14, AS14A, AS22

• Bromide • Chloride • Fluoride • N as Nitrate • N as Nitrite • P as Ortho-phosphate • Sulfate

Method 300.0, Part B • AS9SC, AS9HC, AS23

• All above, plus • Bromate • Chlorite • Chlorate

Method 300.1, Part A • AS9HC, AS14, AS22

• Bromide • Chloride • Fluoride • N as Nitrate • N as Nitrite • P as Ortho-phosphate • Sulfate

Method 300.1, Part B • AS9HC, AS14, AS23

• Bromate • Bromide • Chlorite • Chlorate

9

9

Determination of Inorganic Anions in a Municipal Drinking Water Sample

22941

1 2

3

5 4 6 7 8 10 9

1

2

3

4 5 6

7

8

9 0 1

1 1

11

0.500

–0.200

45.0

−5.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

µS

µS

Column: IonPac AG22 and AS22, 4 mm Eluent: 4.5 mM Sodium carbonate/ 1.4 mM sodium bicarbonate Temperature: 30 °C Flow Rate: 1.2 mL/min Inj. Volume: 25 µL Detection: Suppressed conductivity, ASRS® ULTRA II 4 mm, AutoSuppression recycle mode Peaks 1. Fluoride 0.84 mg/L 2. Formate 0.03 3. Chloride 15.59 4. Nitrite 0.01 5. Unknown NQ 6. Chlorate 0.18 7. Bromide 0.02 8. Nitrate 0.89 9. Carbonate NQ 10. Phosphate 0.22 11. Sulfate 20.45

Very high capacity for anion and organic acid separation

10

IonPac AS22-Fast Anion Column

• New Carbonate RFIC Column format • Designed for fast, isocratic separation of common inorganic anions in

simple sample matrices • Has identical selectivity to the IonPac AS22 column • Shorter column format decreases dead volume, provides faster run

times and allows higher flow rates • Higher throughput • Up to 2.5 mL/min (4 mm) or 0.63 mL/min (2 mm)

• Resolve 7 common anions in less than 5 minutes

Fast anion analysis with AS22-Fast

11

Analysis of a Municipal Drinking Water Sample

–10

100

µS

1 2

3

4 5 6 7 8 9

10

Column: IonPac AS22-Fast, 4 × 150 mm Eluent: 4.5 mM Sodium carbonate 1.4 mM Sodium bicarbonate Flow Rate: 2.0 mL/min Inj. Volume: 100 µL Temperature: 30 °C Detection: Suppressed conductivity, ASRS 300, 4 mm, AutoSuppression recycle mode Peaks: 1. Fluoride 2. Formate 3. Chloride 4. Nitrite 5. Chlorate 6. Bromide 7. Nitrate 8. Carbonate 9. Phosphate 10. Sulfate 0 1 2 3 4 5

–0.56

–0

0.81

µS

1

2

3

4

5

6

7

8 9

10

Minutes 26269

Faster than an AS4A but with 6x capacity

12

Though carbonate eluents are easy to prepare…

• Methods using hydroxide eluents offer more sensitivity than those using carbonate eluents.

• The suppression product is water, providing the lowest possible background conductivity

• Lower noise • Improved detection limits • Larger linear working range

• Preparing hydroxide eluents manually can be difficult to do with high reproducibility.

• The capillary eluent generator can prepare hydroxide eluents with high accuracy and precision for 18 months 24 hours/day, 7 days/week

13

13

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 (A) (B)

Peaks: 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)

19115/19118-01

14

EPA 218.6 Hexavalent Chromium

15

Methodologies for Hexavalent Chromium

• Health concerns • Trivalent chromium is nontoxic • Hexavalent chromium is highly toxic

• Traditional analysis method • EPA Method 218.4 – chelation extraction, atomic

absorption • Subject to positive interference from some metals • Cumbersome – not automated • Modest detection limits (~5 µg/L)

• IC analysis method • EPA Method 218.6 (ASTM Method D5257-03)

IC separation of chromium VI coupled with postcolumn reaction 1,5-diphenylcarbizide) – UV/Vis detection (530 nm)

16

EPA Press Release

“These modifications allow for improved low concentration measurement and are outlined in Dionex Corp. Application Update 144 Determination of Hexavalent Chromium in Drinking Water by Ion Chromatography found at www.dionex.com/en-us/webdocs/4242-AU144_V18.pdf .”

17

Eluent

Autosampler

High-Pressure Nonmetallic

Pump

IonPac® NG1 IonPac AS7

Post column Reagent

System Configuration for Cr(VI) by EPA Method 218.6

Mixing Tee

UV-vis Detector

Knitted Reaction Coil

Waste

Sample Loop

18

Dionex Improvements to EPA Method 218.6

Application Update 144 • Use a lower-sulfate buffer to adjust sample pH • Increase sample size to 1000 µL • Reduce eluent flow rate to 1 mL/min • Reduce PCR flow rate to 0.33 mL/min • Increase postcolumn reaction coil to 750 µL • New MDL in reagent water is 0.018 µg/L – 18 ppt

15x lower detection limit than Method 218.6

19

Hexavalent Chromium in Drinking Water with Optimized EPA Method 218.6

Column: IonPac NG1, AS7 Eluent: 250 mM/L (NH4)2 SO4 100 mM/L NH4OH Flow rate: 1.0 mL/min Inj. volume: 1000 µL Postcolumn reagent: 2 mM/L 1,5-diphenylcarbizide 10 % MeOH 0.5 mol/L H2SO4 Postcolumn flow rate: 0.33 mL/min Reaction coil: 750 µL Detection: UV/Vis, 530 nm Sample: Sunnyvale, CA, tap water (A) Spiked with 0.2 µg/L Cr(VI) (B) Tap water

0 0 2 4 6 8

Cr(VI)

AU

Minutes

Cr(VI) (A)

(B)

0.055 µg/L

0.245 µg/L

21

Cr(VI) 2mm using ICS-2100 with AXP

• High Ionic Strength Water (HIW) vs. DI Water

0 1 2 3 4 5 6 7 8 9 10 -0.7

3.3

Minutes

mAU

Column: IonPac AS7 (2 x 50 mm), AS7 (2 x 250 mm) Eluent: 250 mM (NH4)2 SO4, 100 mM NH4OH Flow: 0.36 mL/min Inj. Vol: 1000 µL Post Column Reagent: 2 mM diphenylcarbazide 10% methanol 1N sulfuric acid Reaction Coil: 125 µL UV Cell: Semi micro (PEEK), 2.5 µL •0.1 µg/L Cr(VI) in DI water •0.1 µg/L Cr(VI) in HIW

Signal offset 5 A

B

22

0 1 2 3 4 5 6 7 8 9 10 -0.5

2.5

Minutes

mAU

Column: IonPacNG1 (2 x 50 mm), AS7 (2 x 250 mm) Eluent: 250 mM (NH4)2 SO4, 100 mM NH4OH Flow: 0.36 mL/min Inj. Vol: 1000 µL Post Column Reagent: 2 mM diphenylcarbazide 10% methanol 1N sulfuric acid Reaction Coil:125 µL A) DI water blank B) 0.007 µg/L Cr(VI) in DI water C) Sunnyvale, CA drinking water 0.05 µg/L

B

C

A

Cr(VI) Analysis using 2 mm format

23

Format comparison

Method Detection Limits for Chromate Based on a 1000 µL Injection

Format

Chromate Conc. (µg/L)

Std. Dev. (µg/L)

RSD (%)

MDL* (µg/L)

4 mm 0.1 0.2

0.0060 0.0056

6.986 3.193

0.018 0.018

2mm 0.001 0.005

0.0003 0.0004

10.03 6.62

0.0009 0.0013

* MDL = (Std. Dev.) x (ts, 99), where ts,99 = 3.14 for n = 7

1 ppt detection with 2 mm Format!

24

EPA 300.1, 557 Drinking Water Disinfection By-products: Bromate and HAA’s

25

EPA 300.1 (B); Trace analysis of bromate using the IonPac® AS23

Columns: IonPac AG23, AS23, 4 mm Eluents: 4.5 mM Sodium carbonate/ 0.8 mM sodium bicarbonate Temperature: 30 °C Flow Rate: 1.0 mL/min Inj. Volume: 200 µL Detection: Suppressed conductivity, ASRS® ULTRA II, 4 mm, AutoSuppression® external water mode Peaks: 1. Fluoride 1.0 mg/L (ppm) 2. Chlorite 0.01 3. Bromate 0.005 4. Chloride 50 5. Nitrite 0.1 6. Chlorate 0.01 7. Bromide 0.01 8. Nitrate 10 9. Carbonate 50 10. Phosphate 0.1 11. Sulfate 50

22949

0 5 10 15 20 25 30 –0.1

0.3

µS

Minutes

6 7 9 10 2 3

4 5 8 11 1

–50

500

µS

0 5 10 15 20 25 30 Minutes

11

4

8 1 6 7 9 5

Carbonate Eluent: AS23 > capacity than AS9HC

26

Column: IonPac® AS19, 4 x 250 mm Eluent : 10 mM KOH from 0 to 7 min, 10 to 15 mM from 7 to 20 min, 15 to 55 mM from 20 to 30 min Eluent Source: EGC-KOH cartridge with CR-ATC Flow Rate: 1.0 mL/min Temperature: 30 C Suppressor: ASRS® ULTRA, 4 mm, external water mode, 300 mA Inj Volume: 500 µL Peaks: 1. Fluoride 1 mg/L (ppm) 2. Formate — 3. Chlorite 0.005 4. Bromate 0.005 5. Chloride 50 6. Nitrite 0.005 7. Chlorate 0.005 8. Bromide 0.005 9. Nitrate 10 10. Carbonate 25 11. Sulfate 50 12. Phosphate 0.2

20282-a

–50 0

300

1 6 7 8

9 10

5 11

12

5 10 15 20 25 30 35 0

µS

2 3 4

2

0.2 5 10 15 20 25 30 –0.035

0.100

µS

Minutes

1

3 4

5 6 7 8

9 10, 11

35

12

Hydroxide Eluent: Allows the use of RFIC (just add water)

RFIC™ System for Anions Using EPA Method 300.0 (B)

27

Column: IonPac® AS19 (0.4 × 250 mm)

Eluent Source: Capillary EGC-KOH cartridge

Eluent: 10 mM KOH (0 to 10 min), 10 to 50 mM KOH (10 to 25 min), 10 mM KOH (25 to 30 min)

Flow Rate: 10 µL/min

Inj. Volume: 10 µL

Temperature: 30 °C

Suppressor: Suppressed conductivity, ACES™ 300 anion capillary electrolytic suppressor

Concentration (µg/L) Peaks: Standard Sample A 1. Chlorite 20 − 2. Bromate 10 10.2 3. Chloride 200 11900 4. Nitrite 20 6.0 5. Chlorate 20 5.5 6. Bromide 8 3.4 7. Nitrate 20 384 8. Carbonate – − 9. Sulfate 500 8860 10. Phosphate 100 −

0 30 –0.10

1.50

µS

Minutes

1 2

3

4

5 6

7

9

10

8

2

− Sample A

− Standard

Oxyhalides and Inorganic Anions in Drinking Water

28

Bromate Method Summary

Technique EPA Method(s) Column(s) Eluent MDL (ppb)

IC-Suppressed Conductivity 300.0 (B) AS9-HC

AS23 AS-19

Carbonate Carbonate Hydroxide

Conductivity 5.0

1.63 0.32

IC-Suppressed Conductivity 300.1 AS9-HC

AS23 AS-19

Carbonate Carbonate Hydroxide

5.0 1.63 0.32

2-D IC Suppressed Conductivity 302.0 (pending)

AS19 4mm, AS-24, 2mm

Hydroxide

0.036

IC - Suppressed Conductivity with postcolumn ODA

317.0 AS9-HC AS-19

Carbonate Hydroxide

Cond. UV

0.32 0.14

IC - Suppressed Conductivity with postcolumn acidified KI

326.1 AS9-HC AS-19

Carbonate Hydroxide 0.29 0.17

IC-ICP-MS 321.8 CarboPac PA100 Hydroxide 0.010

29

United States Environmental Protection Agency TECHNICAL SUPPORT CENTER OFFICE OF GROUND WATER AND DRINKING WATER U. S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268 Office of Research and Development: December 2009

Method 557.0 DETERMINATION OF HALOCAETIC ACIDS, BROMATE, AND DALAPON IN DRINKING WATER BY ION CHROMATOGRAPHY ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMETRY (IC/ESI-MS/MS) A. D. Zaffiro and M. Zimmerman (Shaw Environmental, Inc.) B. V. Pepich (U.S. EPA, Region 10 Laboratory) Rosanne W Slingsby, R. F. Jack and Christopher A. Pohl (Dionex Corporation) D. J. Munch (U.S. EPA, Office of Ground Water and Drinking Water)

HAA’s Without Derivatization

Developed by Dionex

30

What Are HAAs?

Acid Abbreviation Chemical Formula pKa Boiling Point

°C Monochloroacetic acid MCAA* ClCH2CO2H 2.86 187.8

Dichloroacetic acid DCAA * Cl2CHCO2H 1.25a, 1.29b, 1.30c 194

Trichloroacetic acid TCAA * Cl3CCO2H 0.63a, 0.65b, 0.70c 197.5

Monobromoacetic acid MBAA * BrCH2CO2H 2.87a, 2.86b, 2.7c 208

Dibromoacetic acid DBAA * Br2CHCO2H NA 195

Tribromoacetic acid TBAA Br3CCO2H 0.66 245

Bromochloroacetic acid BCAA BrClCHCO2H NA 103.5

Dibromochloro acetic Acid DBCAA Br2ClCCO2H NA NA

Dichlorobromoacet-ic acid DCBAA Cl2ClCCO2H NA NA

* MCAA, DCAA, TCAA, MBAA, DBAA are collectively referred to as HAA5

23456

31

US EPA Method 552.3 Reported Detection Limits (GC-ECD)

• Advantages: • Good selectivity • Low MDLs • Wide applicable concentration

range: 0.5–30 µg/L

• Limitations: • Requires sample pretreatment

• Time consuming • Labor intensive • Subject to multiple

procedural errors

Analyte Detection Limits (µg/L) % Recovery

MCAA 0.20 81 MBAA 0.13 91 DCAA 0.084 98 BCAA 0.029 103 DBAA 0.021 105 TCAA 0.024 107 BDCAA 0.031 113 CDBAA 0.035 112 TBAA 0.097 109

23459

32

EPA 557: Determination of Bromate, Dalapon, and HAA9 by Direct Injection Using IC-MS/MS

Inte

nsity

, cp

s

23472

No sample preparation!

Cl- SO4 CO3 NO3

Diverted to waste

33

Analyte ISTD 5 μg/L

R2 (Calibration range 0.250-20 μg/L) DIW / Matrix*

MDL μg/L / %RSD

(n=7, 1 μg/L) DI water

MDL μg/L / %RSD

(n=7, 1 μg/L) In Matrix*

MCAA MCAA-2-13C

0.9997 / 0.9989 0.51 / 3.5 0.44 / 14.7

MBAA 0.9999 / 0.9990 0.08 / 3.6 0.13 / 4.2

DCAA

DCAA-2-13C

0.9999 / 0.9991 0.39 / 2.0 0.10 / 3.3

BCAA 0.9999 / 0.9992 0.20 / 0.8 0.10 / 0.8

DBAA 0.9999 / 0.9993 0.16 / 5.5 0.33 / 10.8

TCAA

TCAA-2-13C

0.9999 / 0.9993 0.24 / 0.5 0.09 / 0.3

BDCAA 0.9991 / 0.9991 0.26 / 5.0 0.64 / 18.9

CDBAA 0.9992 / 0.9994 0.38 / 5.5 0.52 / 16.4

TBAA 0.9994 / 0.9998 0.26 / 9.2 0.36 / 9.9

Linearity and Minimum Detection Limits of 9 HAAs in DI Water and High Salt Matrix

* Matrix (mg/L) : SO42– 250; Cl– 250; NO3

– 30; NH4Cl 100; HCO3 150;

34

EPA 314.0, 314.2 AND 332 Perchlorate

35

Perchlorate EPA Method Summary (Lowest Concentration Minimum Reporting Level)

Technique EPA MDL in Water

LCMRL ppb

Column(s)

IC-Suppressed Conductivity 314.0* 9058 1 ppb na AS16 or

AS20

IC-Suppressed Conductivity Matrix Rinse-Elimination Primary and Confirmation Columns

314.1* 0.030 ppb 0.150 AS16 AS20

2-D IC Suppressed Conductivity Matrix Rinse-Elimination Primary and Confirmation Columns

314.2* 0.06 0.19 AS16 AS20 with TAC-ULP

IC-MS 332.0** 6860 0.010 ppb 0.050 AS16 or

AS20 IC-MS/MS 332.0**

6860 0.005 ppb 0.020 AS16 or AS20

22481

*Developed by Dionex

** Jointly developed by EPA and Dionex

36

EPA Method 314.0–Determination of 1 µg/L Perchlorate with Increasing Concentrations of Chloride, Sulfate, and Carbonate

Column: IonPac AG16, AS16, 4 mm Eluent: 65 mM KOH Eluent Source: ICS-2000 EG with CR-ATC Temperature: 30 °C Flow Rate: 1.2 mL/min Injection loop: 1000 µL Detection: ASRS® ULTRA II, AutoSuppression®, external water mode, 193 mA Peaks: 1. Perchlorate 1 µg/L

Samples: MA(x) = X mg/L each Cl–, SO4

2–, CO32–

37

0.75

1.35

µS

A: First Dimension

Minutes 0 10 20 30 40

0.40

1.00

1

µS

A) First Dimension Column: IonPac® AG20, AS20, 4 mm Eluent: 35 mM KOH, 0-30 min; 35-60 mM, 30.1-40 min Eluent Source: EG with EGC II KOH Flow Rate: 1.0 mL/min Inj. Volume: 4000 µL Temperature: 30 °C Detection: suppressed conductivity, ASRS ULTRA II, 4 mm, 150 mA B) Second Dimension Concentrator: TAC-ULP1 (5 x 23 mm) Column: IonPac AG16, AS16, 2 mm Eluent: 65 mM KOH Eluent Source: EG with EGC II KOH Flow Rate: 0.25 mL/min Cut Volume: 5 mL Temperature: 30 °C Detection: suppressed conductivity, ASRS ULTRA II, 2 mm, 41 mA Peak: 1. Perchlorate 0.5 µg/L Matrix: Chloride: 1000 mg/L Bicarbonate: 1000 Sulfate: 1000

B: Second Dimension

2-D Perchlorate Analysis in High-Ionic Strength Water

1. Perchlorate

Concentrator

Injection

Accurate detection even in difficult matrices

38

Benefits of Combining Suppressed IC with Mass Spectrometry Detection

Dionex ICS-5000 with MSQ™ Plus

• Separate ionic analytes using standard IC conditions

• Suppressor permits use of high ionic strength eluents to get the benefits of high capacity columns

• Detect and identify analytes with high specificity

• Avoid coeluting interferences to ensure accurate identification

• Avoid background interferences to ensure highest analyte sensitivity

• Identify analytes by mass and isotope ratios for added confirmation

• Internal standard adds to method robustness

• Identify unknowns

39

EPA Method 332.0* IC-MS(/MS) System with Matrix Elimination

Column Flow to Waste (Matrix Elimination) Column Flow to MSQ

Waste

Waste

Matrix Elimination

Valve

* Jointly developed by EPA and Dionex H20 / ACN

Auxiliary Pump

Suppressor

Eluent Generator Injector IC

Column H20 Chromatography

Pump

MSQ™ Mass Spec

40

Advantages of MS Detection vs Conductivity Detection for Perchlorate

• Much greater sensitivity—MRL on order of 5–50 ppt

• Specific determination of two perchlorate isotopes

• Unique perchlorate isotope ratios

• Oxygen-18 Perchlorate isotope can be used as an internal standard for improved method robustness

• Avoids inaccurate identification due to coeluting interferences

• Sensitivity maintained even in high TDS matrices

• MS detection is inherently confirmatory

41

Use of Perchlorate Oxygen-18 Isotope (m/z = 107) as an Internal Standard Ensures Measurement Precision

0

20

40

60

80

100

120

125 250 500 1000 2500 5000 Perchlorate Conc (ppt)

% R

ecov

ery

Area Counts

ISTD Calc

High TDS Matrix: Chloride 1000 ppm Carbonate 1000 Sulfate 1000

42

Perchlorate in California Groundwater EPA Method 332.0 (IC-MS)*

Column: IonPac® AG16, AS16, 2 mm i.d. Suppressor: ASRS® ULTRA, 2 mm Eluent: 65 mM KOH (EG40) Flow Rate: 0.30 mL/min Inj. Volume: 250 µL Detection: 1. Conductivity 2. MSQ, SIM 99, 35CIO4

– MS Conditions: –ESI, 70 V, 350 °C Sample: Groundwater diluted 1/10 Peak: Perchlorate ~ 7–8 μg/L

5 7.5 10 0

18,000

0

4

SIM 99 Counts µS

Minutes

Conductivity

SIM 99

SIM 101 (MDL)99** = 0.04 ppb

* Method developed jointly by EPA and Dionex ** MDL = SD × ts (n = 7), ts = 3.14

43

Perchlorate Analysis Using IC-MS with Matrix Diversion and 50% Acetonitrile Solvent Wash–EPA Method 332.0*

1—1 ppb Perchlorate with 1000 ppm each CCS** 2—1 ppb Perchlorate with 600 ppm each CCS**

3—1 ppb Perchlorate with 100 ppm each CCS**

Cou

nts

1600

10.50 11 11.50 12 12.50 13 13.50 14 14.50 15 600

3

1

SIM 101

Retention Time, Min

**CCS = Chloride, Carbonate, Sulfate

* Method developed jointly by EPA and Dionex

2

44

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