Ion Chromatography: Green Chemistry for a Green Environment Ken Kirkbride Somerset, New Jersey October 12, 2011
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 2
Regulatory Methods that Use Ion Chromatography Chemical or Contaminant Anions ASTM D4327 D4327 D5794 D5827 E1787 WK 5500 E1787 EPA Method Description 300.0 9056 300.1 9056 ISO Method 10304-1 The Determination of Inorganic Anions in Water by Ion Chromatography The Determination of Inorganic Anions in Drinking Water by Ion Chromatography Standard Guide for Determination of Anions in Cathodic Electro-Coat Permeates by Ion Chromatography Test Method for Analysis of Engine Coolant for Chloride and Other Anions by Ion Chromatography Standard Test Method for Anions in Caustic Soda and Caustic Potash (Sodium Hydroxide and Potassium Hydroxide) by Ion Chromatography Standard Test Method for Chloride at Trace Levels in Monoethylene Glycol (Ion Chromatography Method) Standard Test Method for Anions in Caustic Soda and Caustic Potash 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 3
Regulatory Methods that Use Ion Chromatography Chemical or Contaminant ASTM Bromate 300.1 ISO 15061 EPA Method Description The Determination of Inorganic Anions in Drinking Water by Ion Chromatography 302.0 2-D Determination of Bromate by Ion Chromatography Determination of Inorganic Oxyhalide Disinfection By-Products in Drinking 317 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 Determination of Inorganic Oxyhalide Disinfection By-Products in 326 Drinking Water Using Ion Chromatography Incorporating the Addition of Two Postcolumn Reagents for Trace Bromate Analysis 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) 4
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 Perchlorate Solid Waste 6850 6860 Perchlorate in Water, Soils and Solid Wastes Using High-Performance Liquid Chromatography/Electrospray Ionization/Mass Spectrometry Perchlorate in Water, Soils and Solid Wastes Using Ion Chromatography/Electrospray Ionization/Mass Spectrometry 5
Regulatory Methods that Use Ion Chromatography Chemical or Contaminant ASTM Cations D6910-03 Carbohydrate D6919 D5896 Cyanide D6994-04 Haloacetic Acids EPA Method Description 557 Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium in Water and Wastewater by Ion Chromatography Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium in Water and Wastewater by Ion Chromatography Standard Test Method for Carbohydrate Distribution of Cellulosic Materials (Wood Sugars) Standard Test Method for Determination of Metal Cyanide Complexes in Wastewater, Surface Water, Groundwater and Drinking Water using Anion Exchange Chromatography with UV Detection Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) 6
Inorganic Anions in Water EPA 300.0 AND 300.1 7
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 8
Determination of Inorganic Anions in a Municipal Drinking Water Sample 0.500 µs 0.200 45.0 µs 1 2 1 2 3 3 4 5 6 7 8 9 10 456 7 8 9 10 1 11 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 5.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 22941 Very high capacity for anion and organic acid separation 9 9
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 10
Analysis of a Municipal Drinking Water Sample 100 µs 10 0.81 µs 0 1 2 1 2 3 3 4 5 6 7 8 9 4 5 0.56 0 1 2 3 4 5 Minutes 6 7 8 9 10 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 Faster than an AS4A but with 6x capacity 26269 11
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 12
RFIC System for Anions Using EPA Method 300.0 (A) 20 µs 1 2 3 0 0 4 8 12 16 14 (B) 2 Municipal 6 Drinking Water µs (A) 1 Standard 4 5 3 4 5 6 7 0 0 4 8 12 16 Minutes 7 8 8 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 19115/19118-01 13 13
Hexavalent Chromium EPA 218.6 14
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) 15
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/enus/webdocs/4242-au144_v18.pdf. 16
System Configuration for Cr(VI) by EPA Method 218.6 Eluent Autosampler High-Pressure Nonmetallic Pump Sample Loop IonPac NG1 IonPac AS7 Post column Reagent Mixing Tee Knitted Reaction Coil UV-vis Detector Waste 17
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 18
Hexavalent Chromium in Drinking Water with Optimized EPA Method 218.6 AU 0 (A) (B) Cr(VI) 0.245 µg/l Cr(VI) 0.055 µg/l 0 2 4 6 8 Minutes Column: IonPac NG1, AS7 Eluent: 250 mm/l (NH 4 ) 2 SO 4 100 mm/l NH 4 OH Flow rate: 1.0 ml/min Inj. volume: 1000 µl Postcolumn reagent: 2 mm/l 1,5-diphenylcarbizide 10 % MeOH 0.5 mol/l H 2 SO 4 Postcolumn flow rate: 0.33 ml/min Reaction coil: 750 µl Detection: Sample: UV/Vis, 530 nm Sunnyvale, CA, tap water (A) Spiked with 0.2 µg/l Cr(VI) (B) Tap water 19
Cr(VI) 2mm using ICS-2100 with AXP High Ionic Strength Water (HIW) vs. DI Water 3.3 mau Column: IonPac AS7 (2 x 50 mm), AS7 (2 x 250 mm) Eluent: 250 mm (NH 4 ) 2 SO 4, 100 mm NH 4 OH 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 A Signal offset 5-0.7 0 1 2 3 4 5 6 7 8 9 10 Minutes B 21
Cr(VI) Analysis using 2 mm format 2.5 mau C B A Column: IonPacNG1 (2 x 50 mm), AS7 (2 x 250 mm) Eluent: 250 mm (NH 4 ) 2 SO 4, 100 mm NH 4 OH 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 -0.5 0 1 2 3 4 5 6 7 8 9 10 Minutes 22
Format comparison Format Chromate Conc. (µg/l) Method Detection Limits for Chromate Based on a 1000 µl Injection 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 1 ppt detection with 2 mm Format! 23 * MDL = (Std. Dev.) x (t s, 99 ), where t s,99 = 3.14 for n = 7
Drinking Water Disinfection By-products: Bromate and HAA s EPA 300.1, 557 24
EPA 300.1 (B); Trace analysis of bromate using the IonPac AS23 0.3 µs 0.1 500 µs 50 1 2 3 4 5 8 11 6 7 0 5 10 15 20 25 30 Minutes 4 9 1 5 67 8 9 10 11 0 5 10 15 20 25 30 Minutes Carbonate Eluent: AS23 > capacity than AS9HC 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 25
RFIC System for Anions Using EPA Method 300.0 (B) 300 µs 0 50 0 0.100 µs 5 11 1 9 234 12 6 78 10 5 10 15 20 25 30 35 9 10, 11 12 1 5 6 7 8 23 4 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 0.035 0.2 5 10 15 20 25 30 Minutes Hydroxide Eluent: Allows the use of RFIC (just add water) 35 20282-a 26
Oxyhalides and Inorganic Anions in Drinking Water Column: IonPac AS19 (0.4 250 mm) Eluent Source: Capillary EGC-KOH cartridge 1.50 3 8 9 Eluent: KOH min) Flow Rate: 10 mm KOH (0 to 10 min), 10 to 50 mm (10 to 25 min), 10 mm KOH (25 to 30 10 µl/min Inj. Volume: 10 µl Sample A Standard Temperature: 30 C Suppressor: Suppressed conductivity, ACES 300 anion capillary electrolytic suppressor µs 10 2 4 7 1 2 5 6 0.10 0 30 Minutes 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 27
Bromate Method Summary Technique IC-Suppressed Conductivity EPA Method(s) 300.0 (B) IC-Suppressed Conductivity 300.1 Column(s) Eluent MDL (ppb) AS9-HC AS23 AS-19 AS9-HC AS23 AS-19 Carbonate Carbonate Hydroxide Carbonate Carbonate Hydroxide Conductivity 5.0 1.63 0.32 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 28
HAA s Without Derivatization 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) 29 Developed by Dionex
What Are HAAs? Acid Monochloroacetic acid Abbreviation Chemical Formula pka Boiling Point C MCAA* ClCH 2 CO 2 H 2.86 187.8 Dichloroacetic acid DCAA * Cl 2 CHCO 2 H 1.25 a, 1.29 b, 1.30 c 194 Trichloroacetic acid TCAA * Cl 3 CCO 2 H 0.63 a, 0.65 b, 0.70 c 197.5 Monobromoacetic acid MBAA * BrCH 2 CO 2 H 2.87 a, 2.86 b, 2.7 c 208 Dibromoacetic acid DBAA * Br 2 CHCO 2 H NA 195 Tribromoacetic acid TBAA Br 3 CCO 2 H 0.66 245 Bromochloroacetic acid Dibromochloro acetic Acid Dichlorobromoacetic acid BCAA BrClCHCO 2 H NA 103.5 DBCAA Br 2 ClCCO 2 H NA NA DCBAA Cl 2 ClCCO 2 H NA NA * MCAA, DCAA, TCAA, MBAA, DBAA are collectively referred to as HAA5 30 23456
US EPA Method 552.3 Reported Detection Limits (GC-ECD) Advantages: Good selectivity Low MDLs Wide applicable concentration range: 0.5 30 µg/l Analyte Detection Limits (µg/l) % Recovery MCAA 0.20 81 MBAA 0.13 91 DCAA 0.084 98 Limitations: Requires sample pretreatment Time consuming Labor intensive Subject to multiple procedural errors BCAA 0.029 103 DBAA 0.021 105 TCAA 0.024 107 BDCAA 0.031 113 CDBAA 0.035 112 TBAA 0.097 109 31 23459
EPA 557: Determination of Bromate, Dalapon, and HAA9 by Direct Injection Using IC-MS/MS Diverted to waste Cl - SO 4 CO 3 NO 3 Intensity, cps No sample preparation! 32 23472
Linearity and Minimum Detection Limits of 9 HAAs in DI Water and High Salt Matrix Analyte ISTD 5 μg/l R 2 (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 0.9997 / 0.9989 0.51 / 3.5 0.44 / 14.7 MCAA-2-13C MBAA 0.9999 / 0.9990 0.08 / 3.6 0.13 / 4.2 DCAA 0.9999 / 0.9991 0.39 / 2.0 0.10 / 3.3 BCAA DCAA-2-13C 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 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 TCAA-2-13C 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 33 * Matrix (mg/l) : SO 4 2 250; Cl 250; NO 3 30; NH 4 Cl 100; HCO 3 150;
Perchlorate EPA 314.0, 314.2 AND 332 34
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 2-D IC Suppressed Conductivity Matrix Rinse-Elimination Primary and Confirmation Columns 314.1* 0.030 ppb 0.150 314.2* 0.06 0.19 AS16 AS20 AS16 AS20 with TAC-ULP IC-MS 332.0** 6860 IC-MS/MS 332.0** 6860 *Developed by Dionex 0.010 ppb 0.050 0.005 ppb 0.020 AS16 or AS20 AS16 or AS20 ** Jointly developed by EPA and Dionex 35 22481
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, SO 4 2, CO 3 2 36
2-D Perchlorate Analysis in High-Ionic Strength Water 1.35 µs A: First Dimension 1. Perchlorate 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 0.75 1.00 Concentrator B: Second Dimension Injection 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 µs 0.40 0 10 20 30 40 Minutes 1 Peak: Matrix: Chloride: 1000 mg/l Bicarbonate: 1000 Sulfate: 1000 1. Perchlorate 0.5 µg/l Accurate detection even in difficult matrices 37
Benefits of Combining Suppressed IC with Mass Spectrometry Detection Separate ionic analytes using standard IC conditions Suppressor permits use of high ionic strength eluents to get the benefits of high capacity columns Dionex ICS-5000 with MSQ Plus 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 38
EPA Method 332.0* IC-MS(/MS) System with Matrix Elimination H 2 0 Chromatography Pump Eluent Generator Injector IC Column Matrix Elimination Valve Suppressor Column Flow to Waste (Matrix Elimination) Column Flow to MSQ MSQ Mass Spec Waste * Jointly developed by EPA and Dionex H 2 0 / ACN Auxiliary Pump Waste 39
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 40
Use of Perchlorate Oxygen-18 Isotope (m/z = 107) as an Internal Standard Ensures Measurement Precision 120 100 % Recovery 80 60 40 Area Counts ISTD Calc 20 0 125 250 500 1000 2500 5000 Perchlorate Conc (ppt) High TDS Matrix: Chloride 1000 ppm Carbonate 1000 Sulfate 1000 41
Perchlorate in California Groundwater EPA Method 332.0 (IC-MS)* 18,000 SIM 99 Counts Conductivity SIM 99 4 µs 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, 35 CIO 4 MS Conditions: ESI, 70 V, 350 C Sample: Groundwater diluted 1/10 Peak: Perchlorate ~ 7 8 μg/l SIM 101 (MDL) 99 ** = 0.04 ppb 0 0 5 7.5 10 * Method developed jointly by EPA and Dionex Minutes ** MDL = SD t s (n = 7), t s = 3.14 42
Perchlorate Analysis Using IC-MS with Matrix Diversion and 50% Acetonitrile Solvent Wash EPA Method 332.0* 1600 Counts SIM 101 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** **CCS = Chloride, Carbonate, Sulfate 3 1 2 600 10.50 11 11.50 12 12.50 13 13.50 14 14.50 15 Retention Time, Min * Method developed jointly by EPA and Dionex 43
44 ThermoFisher is committed to IC Environmental Methods