Chromatography: Comparison of EPA Methods 300.1, 317, 326 and 302 for Bromate Analysis Part 1

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(originally aired 03-29-12) …

(originally aired 03-29-12)

Initially U.S. EPA 300.1 (Ion Chromatography with conductivity detection) sufficed for bromate regulatory requirements. As bromate toxicity concerns increased, lower regulatory limits (and lower MDLs) were imposed, leading to use of EPA 317’s and 326’s postcolumn derivatization and visible detection methods, although they sacrifice robustness and ease of use. Simultaneously, enhancements in column chemistry improved the MDLs possible with EPA 300.1. And since it is still impossible to overcome matrix effects with certain drinking water samples, EPA 302’s 2-D IC method was approved to maintain testing ease-of-use and robustness. Here, experts detail the bromate analysis methods and necessary validation steps.

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  • 1. Comparison of EPA Methods 300.1, 317, 326 and 302 for Bromate Analysis Part 1 Richard F. Jack, PhD Manager, Global Market Development March 29, 2012
  • 2. Bromate Regulations and Method Comparisons • Disinfection byproducts • Toxicology • Bromate method summary • EPA Method 300.1 • EPA Methods 300.1 and 317 • EPA Methods 300.1 and 326 • Conductivity detection for bromate analysis • Method comparison using Thermo Scientific Dionex IonPac AS23 and AS19 columns • Method comparisons using Dionex IonPac™ AS9-HC and AS19 columns • Matrix interference and analysis of bromate • Two-dimensional ion chromatography (2D-IC)
  • 3. Drinking Water Disinfection: Treatment and Byproducts  Disinfection byproducts are formed when disinfectants used in water treatment plants react with bromide and/or natural organic matter. Disinfection Treatment Disinfection Byproducts Chlorination Trihalomethanes Haloacetic Acids Chlorate Chlorine Dioxide Chlorite Chlorate Chloramine Chlorate Ozonation Bromate
  • 4. Toxicology of Bromate • Clinical signs of bromate poisoning in humans include: • Anemia, hemolysis, renal failure, hearing loss.* • Carcinogenicity: • Animals: International Agency for Research on Cancer (IARC) has concluded that bromate is carcinogenic in animals. • Humans: IARC has assigned bromate to Group 2B (possibly carcinogenic to humans). * World Health Organization (WHO), Geneva, Switzerland, 2000
  • 5. EPA Bromate Method Summary EPA Methods Column(s) 300.0 (B) Dionex Ion Pac AS9-HC AS23 AS19 Carbonate Carbonate Hydroxide IC-Suppressed Conductivity 300.1 Dionex IonPac AS9-HC AS23 AS19 Carbonate Carbonate Hydroxide 2D-IC Suppressed Conductivity 302.0a Dionex IonPac AS19, 4 mm AS24, 2 mm Hydroxide 317.0 Dionex IonPac AS9-HC AS19 Carbonate Hydroxide IC Suppressed Conductivity with Postcolumn Acidified KI 326.1 Dionex IonPac AS9-HC AS19 Carbonate Hydroxide IC-ICP-MS 321.8 Dionex CarboPac PA100 Technique IC Suppressed Conductivity IC Suppressed Conductivity with Postcolumn ODA Eluent MDL (ppb) Conductivity 5.0 0 1.63 0.32 5.0 0 1.63 0.32 0.036 Conductivity UV 0.32 0.14 0.29 0.17 0.01
  • 6. Bromate Method, Application Note and Matrix Recommendations EPA Method Application Note IC Suppressed Conductivity 300.0 (B) 167, 184 Low salt conditions IC Suppressed Conductivity 300.1 167, 184 Low salt conditions IC Suppressed Conductivity with Postcolumn ODA 317.0 168 Tolerates higher salt conditions IC Suppressed Conductivity with Postcolumn Acidified KI 326.1 171 Tolerates higher salt conditions 2D-IC Suppressed Conductivity 302.0 187 Tolerates higher salt conditions IC-ICP-MS 321.8 Technique Matrix Tolerates higher salt conditions
  • 7. Bromate Method, Application Note and Matrix Recommendations (cont’d) Application Note Technique Method IC Chemically Suppressed Conductivity ISO 15061, ASTM 6581 167, 184 IC Suppressed Conductivity with Postcolumn Acidified KI ISO Pending 171 IC Suppressed Conductivity with Postcolumn Acidified KBr Japan Matrix Drinking water only, ground- and wastewater only if low salt conditions Tolerates higher salt conditions. Tolerates higher salt conditions.
  • 8. Bromate Regulations and Methods Timeline 1993: WHO MCL 25 ppb 1993: EPA 300.0 2003: WHO MCL 10 ppb 1998: U.S. EPA MCL of 10 ppb EU MCL 50 to 10 ppb 1997: EPA 300.1 2004: U.S. stage II DBP Rule MCLG “0” U.S. FDA regulates in BW 2000: EPA 317 2009: EPA 302 2002: EPA 326 1995: AN 101 Carbonate 2003: AN 149 Carbonate, Postcolumn I3 2004: AN 136 Carbonate, Postcolumn ODA, AN 167 Hydroxide, Dionex IonPac AS19 2009: AN 208 Carbonate, CRD Dionex IonPac AS23 2006: AN 168 Hydroxide Postcolumn ODA 2009: AN 171 Hydroxide, Postcolumn I3 New Dionex IonPac AS19 2007: AN 184 Hydroxide, Carbonate Eluent Comparison 2007: AN 187 Hydroxide, 2D- IC
  • 9. EPA 300.1 Comparison of Dionex IonPac AS9-SC and AS9-HC Columns for Oxyhalide Determination 1 14 Columns: 6 8 7 3 2 µS A 9 Flow Rate: 1 mL/min Inj. Volume: 25 µL Detection: Suppressed Conductivity, Thermo Scientific Dionex ASRS Anion SelfRegenerating Suppressor,Thermo Scientific Dionex AutoSuppression device, external water mode 10 B 4 µS 2 3 8 6 5 7 10 Peaks: 9 0 0 5 A. 1.8 mM Sodium carbonate 1.7 mM Sodium bicarbonate B. 9.0 mM Sodium carbonate 10 0 1 A. Dionex IonPac AG9-SC, AS9-SC B. Dionex IonPac AG9-HC, AS9-HC Eluent: 45 10 15 Minutes 20 25 1. Fluoride 2. Chlorite 3. Bromate 4. Chloride 5. Nitrite 6. Bromide 7. Chlorate 8. Nitrate 9. o-Phosphate 10. Sulfate 3.0 mg/L 10.0 20.0 6.0 15.0 25.0 25.0 25.0 40.0 30.0
  • 10. Effect of Matrix Concentration on Bromate Peak Shape and Recovery Column: Dionex IonPac AG9-HC, AS9-HC, 4 mm Flow Rate: 1.0 mL/min Concentration: 9.0 mM Carbonate Suppressor: Thermo Scientific Dionex AAES Anion Atlas Electrolytic Suppressor Current: 58mA Loop: 500 µL (large loop) Oven: 30 °C E 1 D 1 C µS Peak 1: 1 Bromate 0.005 mg/L B Matrix Concentration: E D C B A 1 A 1 0 4 Minutes 8 12 200 ppm of CI and SO4 150 100 50 0
  • 11. System Configuration EPA Methods 300.1 and 317 for Bromate Pump Guard PCR Reservoir ODA Separation Mixing Tee Absorbance Detector Suppressor Conductivity Detector
  • 12. EPA Methods 300.1 and 317 for Trace Bromate Flow Rate: µS 1 2 0 0 5 (B) 12 AU 45 10 15 20 Method 317.0 1.3 mL/min 225 mL Detection: Method 300.1 9.0 mM Sodium carbonate Inj. Volume: (A) Dionex IonPac AG9-HC, AS9-HC (4 × 250 mm) Eluent: 3 0.25 0.015 Column: A) Suppressed conductivity Dionex ASRS™ ULTRA, Dionex AutoSuppression™ external water mode B) Absorbance, 450 nm Postcolumn Reagent: PCR Flow Rate: 0.7 mL/min Postcolumn Heater: Peaks: 0 0 5 10 Minutes o-dianisidine 15 20 60 °C 1. Chlorite 2. Bromate 3. Surrogate (DCAA) 4. Bromide 5. Chlorate 20 mg/L (ppb) 5 1000 20 20 Chromatograms courtesy of Herb Wagner, U.S. EPA.
  • 13. System Configuration for EPA Method 300.1 and 326.0 for Trace Bromate Pump PC10 PCR Reservoir KI Guard Suppressor Separation Thermo Scientific Dionex AMMS MicroMembrane Suppressor KI→HI Mixing Tee BrO3– + HI → I3 Color (352) nm) Conductivity Detector Knitted RX Coil PCH-2 Heater Absorbance Detector Waste
  • 14. Details of Postcolumn Reagent Generation with Dionex AMMS™ III CationExchange Membrane Waste CationExchange Membrane From PC10 Waste KI K+ HSO4– K+ HSO4– K+ K+ I I – – H+ H+ H+ + I– H+ HSO4– H+ HSO4– 300 mM Sulfuric Acid 300 mM Sulfuric Acid To Mixing Tee
  • 15. Bromate Oxidizes Iodide to Triiodide in EPA Method 326 through Postcolumn Reaction Mixing Tee KI + H+ from Dionex AMMS BrO3– + 3I– + 3H+ 3HOI + 3I– + 3H+ 3I2– + 3I– Bromate from Column 3HOI + Br– 3I2 + 3H2O 3I3– I3– Detect I3– at 352 nm
  • 16. Analysis of Bromate and Common Anions in Bottled Water 27.10 3 (A) µS Column: Eluent: Temp: Flow Rate: Inj. Volume: Detection: Method 300.1 5 2 4 26.10 0 0.004 5 10 15 (B) Method 326.0 AU Postcolumn Reagent: Acidified KI 20 PCR Flow Rate: 0.4 mL/min Postcolumn Heater: 80 °C Peaks: 2 Dionex IonPac AG9-HC, AS9-HC, 4 mm 9.0 mM Sodium carbonate 30 °C 1.3 mL/min 225 µL A) Suppressed conductivity, Dionex AAES Anion Atlas™ Electrolytic Suppressor, external water mode B) Absorbance, 352 nm A) 1. 2. 3. 4. 5. Conductivity Chlorite not detected Bromate 1.52 µg/L (ppb) DCA* Bromide 1.12 Chlorate 1.08 B) Postcolumn Reagent/UV 2. Bromate 1.84 µg/L (ppb) –0.001 0 5 10 Minutes 15 20 * DCA = Dichloroacetate quality control surrogate
  • 17. Evalution of EPA Methods 300.1, 317, and 326 • EPA Method 300.1 (B/C) with conductivity detection • High LOD • Chloride removal required with some samples leading to added costs and time • EPA Method 317 postcolumn addition of ODA followed by visible detection • • • • Requires extra hardware Requires frequent optimization of PCR reagent flow rate Reagent purity was an issue Handling of ODA a human carcinogen • EPA Method 326 postcolumn addition of hydroiodic acid that combines with bromate to form the triiodide anion followed by UV-vis detection • Requires hardware • Requires in situ generation of hydroiodic acid by the acidification of potassium iodide • Potassium iodide is photo-sensitive • Requires frequent optimization of PCR reagent flow rate
  • 18. Improving EPA Method 300.1 Conductivity Detection for Bromate • Hydroxide eluent suppression produces water, providing the lowest possible background conductivity • • • • Lower noise Improved detection limits Larger linear working range Eluent is conveniently generated on line • New columns with increased capacity bind matrix anions like Cl. Year Column Capacity Eluent 1993 Dionex IonPac AS9SC 30 carbonate 1993 Dionex IonPac AS9HC 190 carbonate 2007 Dionex IonPac AS23 320 carbonate 2007 Dionex IonPac AS19 240 hydroxide
  • 19. Chromatogram of Mineral Water A Spiked with 1 µg/L Each Chlorite and Chlorate and 0.5 µg/L Bromate Column: Eluent: Dionex IonPac AG19, AS19 4 mm 10 mM KOH 0–10 min, 10–45 mM 10–25 min, 45 mM 25–30 min Eluent Source: Thermo Scientific Dionex EGC II KOH with CR-ATC Temperature: 30 °C Flow Rate: 1.0 mL/min Inj. Volume: 250 µL Detection: Suppressed conductivity, Dionex ASRS ULTRA II, recycle mode 1 2 0.5 1 4 8 9 3 10 11 Peaks: µS 0.2 0 5 10 15 Minutes 20 25 30 1. Fluoride 2. Chlorite 1.0 µg/L 3. Bromate 0.5 4. Chloride 5. Nitrite 6. Chlorate 1.0 7. Bromide 8. Nitrate 9. Carbonate 10. Sulfate 11. Phosphate
  • 20. Hydroxide vs Carbonate Eluents for Separation of Common Anions and DPBs in Mineral Water Column: 0.5 A 1 8 4 9 10 A) Dionex IonPac AS19 B) Dionex IonPac AS23 Eluent: A. Hydroxide B. Carbonate/bicarbonate Detection: Suppressed conductivity 11 7 µS Peaks 6 2 1. Fluoride 2. Chlorite 8.8 3. Bromate 4.7 4. Chloride 5. Nitrite 6. Chlorate 13.5 7. Bromide 8. Nitrate 9. Carbonate 10. Sulfate 11. Orthophosphate 5 3 0.2 0.7 B 1 4 8 10 11 9 µS A B 11.3 µg/L 5.1 9.5 3 2 5 6 7 -0.1 0 5 10 15 Minutes 20 25 30 • Both eluents show excellent anion and oxyhalide separation. • Trace oxyhalides chlorite, bromate, and chlorate are well resolved. • Hydroxide does not show the water dip. • Elution order of orthophosphate and sulfate are reversed.
  • 21. Reagent-Free™ IC (RFIC™) System Using Hydroxide Is Sensitive—Hydroxide vs Carbonate Eluents Analyte Range (µg/L) Linearity (r2) Retention Time Precision (% RSDb,c) Peak Area Precision (% RSD) MDL Standard (µg/L) MDL Calculated (µg/L) Dionex IonPac AS19 Column—Hydroxide Eluent Chlorite 2-50 0.9999 0.04 1.20 1.0 0.18 Bromate 1-25 0.9995 0.03 1.40 2.0 0.31 Chlorate 2-50 0.9999 0.01 0.54 1.0 0.28 Dionex IonPac AS23 Column—Carbonate/Bicarbonate Eluent Chlorite 10-50 0.9999 0.07 2.20 5.0 1.02 Bromate 5-25 0.9998 0.07 2.63 5.0 1.63 Chlorate 10-50 0.9998 0.11 2.48 9.0 2.05 a b c See Application Note 184 for conditions RSD = relative standard deviation, n = 7 Quality control standard contained 10 ppb each of chlorite, chlorate, and bromide and 5 ppb bromate
  • 22. Resolution and Sensitivity Improvement with Hydroxide Eluent + Gradient Separation Chloride (Dionex IonPac AS18 column, hydroxide) 3.0 1 min µS 0 –0.5 2.0 1 min µS 0 –0.5 Area: 0.2743 µS•min Height: 2.98 µS Plates: 22,843 EP Chloride (Dionex IonPac AS14 column, carbonate) Area: 0.1767 µS•min Height: 1.35 µS Plates: 5,172 EP Sulfate (Dionex IonPac AS18 column, hydroxide) Area: 0.185 µS•min Height: 1.97 µS Plates: 42,068 EP Sulfate (Dionex IonPac AS14 column, carbonate) Area: 0.1301 µS•min Height: 0.35 µS Plates: 4,644 EP
  • 23. Affect of Cl Concentration on Bromate Recovery Using a Dionex IonPac AS19 Column 100 80 60 % RSD Bromate Recovery 40 20 0 0 50 100 150 Cl conc (ppm) 200 250
  • 24. Comparison of EPA Methods 300.1, 317, 326 and 302 for Bromate Analysis Part 2: Quality Assurance Requirements for EPA Method Development Herbert P. Wagner, Analytical Chemist March 29, 2012 1
  • 25. Outline • Challenge to analyze trace levels of an analyte in large excess of interfering components • Surface and ground waters vary across the United States • Synthetic matrices and other quality assurance protocols incorporated by U.S. EPA Office of Ground Water and Drinking Water (OGWDW) to ensure method precision, accuracy and robustness 2
  • 26. Quality Assurance Requirements for EPA Method Development • High-ionic-strength matrices may overload exchange sites on the column and cause dramatic shifts in retention time. • Suppressed ion chromatographic (IC) methods for inorganic anions were first used by U.S. EPA Office of Research and Development in late 1980’s. • Information Collection Rule (ICR) for bromate occurrence data in U.S. was scheduled from July 1997 to early 1999. 3
  • 27. Quality Assurance Requirements for EPA Method Development • Selective Anion Concentration (SAC) Method was developed by U.S. EPA Office of Water in 1995-96. • Very complex research method used to support bromate data collection during ICR • Never published as an EPA monitoring method • Bromate occurrence data collected during ICR showed need for more user-friendly method required for bromate. 4
  • 28. Quality Assurance Requirements for EPA Method Development • Pretreatment cartridges used to remove anionic interferences in SAC method • Introduction of Thermo Scientific Dionex IonPac AS-9 HC column afforded fourfold increase in injection volume, and therefore increased detection limit (DL) for bromate • Increased injection volume created larger interferences which could overshadow gains in sensitivity 5
  • 29. Quality Assurance Requirements for EPA Method Development • EPA Method 300.1 introduced in 1997 provided a more user-friendly, sensitive method for analysis of bromate in drinking water. • Synthetic high ionic water (HIW) was first introduced as QC sample to ensure DL not affected by ionic strength matrix. • HIW was a reagent water containing 100mg/L each of carbonate, chloride and sulfate and 10mg/L nitrate (as N) and phosphate (as P). 6
  • 30. Quality Assurance Requirements for EPA Method Development • Lowest Concentration Minimum Reporting Level (LCMRL) was introduced by EPA OGWDW in 2004. • Difficult to find consistently uniform fulvic/humic acid • HOW replaced with municipal surface water with a year-round total organic carbon (TOC) of 4–5 mg/L. 8
  • 31. Quality Assurance Requirements for EPA Method Development • The complexity of two-dimensional IC required the very stringent QA protocols developed by EPA OGWDW for the analysis bromate and perchlorate be implemented into EPA Methods 302.0 and 314.2. • A printout of the first dimension high level Continuing Calibration Check (CCC) and Laboratory Fortified Synthetic Sample Matrix (LFSSM) CCC chromatograms was the final QA requirement implemented. • These requirements ensure that the target analyte falls within the “cut window” in reagent water (RW) and very high ionic Laboratory Synthetic Sample Matrix (LSSM). 9
  • 32. Quality Assurance/Control Definitions • Analysis Batch: A sequence of field samples, which are analyzed within a 24-hour period and include no more than 20 field samples. An Analysis Batch must also include all required QC samples which do not contribute to the maximum field sample total of 20. • Laboratory Reagent Blank (LRB): An aliquot of reagent water or other blank matrix that is treated exactly as a sample, including exposure to storage containers. The LRB is used to determine if the method analyte or other interferences are present in the laboratory environment, reagents, or apparatus. 10
  • 33. Quality Assurance/Control Definitions (Cont’d) • Calibration Standard (CAL STD): A solution of the target analyte prepared from a Primary Dilution Solution. The CAL solutions are used to calibrate the instrument response with respect to analyte concentration. • Continuing Calibration Check Standard (CCC): A calibration check standard containing the method analyte, which is analyzed periodically throughout an Analysis Batch to verify the accuracy of the existing calibration for that analyte. 11
  • 34. Quality Assurance/Control Definitions (Cont’d) • Laboratory Fortified Blank (LFB): An aliquot of reagent water or other blank matrix to which a known quantity of the method analyte is added. The LFB is analyzed exactly like a sample. Its purpose is to determine whether the methodology is in control, and whether the laboratory is capable of making accurate and precise measurements. • Laboratory Duplicate (LD): Two sample aliquots (LD1 and LD2) from a single field sample bottle analyzed separately with identical procedures. Analyses of LD1 and LD2 indicate precision associated specifically with laboratory procedures by removing variation contributed from sample collection and storage procedures. 12
  • 35. Quality Assurance/Control Definitions (Cont’d) • Laboratory Fortified Sample Matrix (LFSM): An aliquot of a field sample to which a known quantity of the method analyte is added. The LFSM is processed and analyzed exactly like a field sample, and its purpose is to determine whether the field sample matrix contributes bias to the analytical results. The background concentration of the analyte in the field sample matrix must be determined in a separate aliquot and the measured value in the LFSM corrected for the native concentration. • Laboratory Fortified Sample Matrix Duplicate (LFSMD): A second aliquot of the field sample used to prepare the LFSMD, which is fortified and analyzed identically to the LFSM. The LFSMD is used instead of the Laboratory Duplicate to assess method precision and accuracy when the occurrence of the target analyte is infrequent. 13
  • 36. Quality Assurance/Control Definitions (Cont’d) • Laboratory Synthetic Sample Matrix (LSSM): An aliquot of reagent water that is fortified with the sodium salts of chloride, bicarbonate, sulfate and, if required, phosphate and nitrate. The purpose of the LSSM is to ensure method precision and accuracy in a simulated very-high-ionic-strength drinking water matrix. • Laboratory Fortified Synthetic Sample Matrix (LFSSM): An aliquot of the LSSM which is fortified with the target. The LFSSM is used to set the start time for the cut window in the first dimension and also used to ensure the precision and accuracy for the method is in control. The LFSSM samples are treated like the CCCs. 14
  • 37. Quality Assurance/Control Definitions (Cont’d) • Laboratory Fortified Synthetic Sample Matrix Continuing Calibration Check Standard (LFSSM CCC): An aliquot of the LSSM which is fortified with the target analyte at a concentration equal to one of the CCCs. A LFSSM CCC at a concentration equal to the highest calibration level should be analyzed near the beginning or at the end of each Analysis Batch to confirm that the first dimension heart-cutting procedure has acceptable recovery in high inorganic matrices. 15
  • 38. Quality Assurance/Control Definitions (Cont’d) • Lowest Concentration Minimum Reporting Level (LCMRL): The single-laboratory LCMRL is the lowest true concentration for which the future recovery is predicted to fall between 50–150% recovery with 99% confidence. • Minimum Reporting Level (MRL): The minimum concentration that can be reported by a laboratory as a quantified value for the target analyte in a sample following analysis. This defined concentration must be no lower than the concentration of the lowest calibration standard for the target. 16
  • 39. Analysis Batch Sequence Injection # Sample Description Acceptance Criteria 1 LRB ≤ 1/3 MRL 2 CCC at the MRL Recovery of 50–150% 3 LFB ≤ MRL 50–150% of Value > MRL 80–120% of Value 4 Sample 1 Normal Analysis 5 Sample 2 Normal Analysis 6 Sample 2 LFSM Recovery of 80–120% 7 Sample 2 LFSMD % RPD = ± 20% 8 Sample 3 Normal Analysis 9 Sample 4 Normal Analysis 10 Sample 5 Normal Analysis 11 Sample 6 Normal Analysis 12 Sample 7 Normal Analysis 17
  • 40. Analysis Batch Sequence (Cont’d) Injection # Sample Description Acceptance Criteria 13 Sample 8 Normal Analysis 14 Sample 9 Normal Analysis 15 Sample 10 Normal Analysis 16 CCC at Mid Level Recovery of 80–120% 17 Sample 11 Normal Analysis 18 Sample 12 Normal Analysis 19 Sample 13 Normal Analysis 20 Sample 14 Normal Analysis 21 Sample 15 Normal Analysis 22 Sample 16 Normal Analysis 23 Sample 17 Normal Analysis 24 Sample 18 Normal Analysis 18
  • 41. Analysis Batch Sequence (Cont’d) Injection # Sample Description Acceptance Criteria 25 Sample 19 Normal Analysis 26 Sample 20 Normal Analysis 27 CCC at High Level * Recovery of 80–120% 28 LFSSM CCC at High Level * Recovery of 80–120% * Printout of first-dimension chromatogram required 19
  • 42. EPA Method 302.0 Two-Dimensional Matrix Elimination IC • Introduced for the trace analysis in the presence of large amount of matrix ions • Uses a high capacity 4 mm column in the first dimension to separate the analytes from the matrix ions • After separation, the suppressed effluent portion containing the analytes is concentrated onto a concentrator column and subsequently analyzed in the second dimension using a smaller format column with a different selectivity 20
  • 43. EPA Method 302.0 Two-Dimensional Matrix Elimination IC (cont.) – resulting in enhanced sensitivity and selectivity – introduction of capillary scale ion chromatography provides a unique opportunity to further improve the detection limits by using the capillary scale ion chromatography in the second dimension – outline 2-D methods used for the analysis of anions in drinking water – 2-D method for bromate in drinking water 21
  • 44. Current Approaches in IC Trace Analysis • Samples with Low Levels of Matrix Ion • – Analysis is typically performed using preconcentration or large-volume direct injections – Example applications: Analysis of ultrapure water (UPW) Samples with High Levels of Matrix Ions – Pre-concentration or large-volume direct injection may not be possible because the matrix ions may co-elute with species of interest or may elute species of interest leading to recovery and integration issues due to band broadening – Example applications: Analysis of drinking water, wastewater 22
  • 45. Current Approaches in IC Trace Analysis (cont’d) • Samples with High Levels of Matrix Ions – Requires a sample pretreatment step using solidphase extraction (SPE) cartridges • Example: A silver form cation-exchange resin used to remove high levels of chloride • Multiple cartridges may be needed • SPE methods – Off-line method – Labor intensive – adds costs from cartridges and equipment 23
  • 46. Matrix Elimination Ion Chromatography (MEIC) Features Large-Loop • Allowscolumn) Injection in the First Dimension (4 mm – Possible to inject a larger loop volume than the standard approach because the capacity and selectivity of the analytical column in the first dimension dictates the recovery, and the analyte of interest is analyzed in the second dimension • Focuses Ions of Interest in a Concentrator Column After Suppression in the First Dimension – Hydroxide eluent converted to DI water, providing an ideal environment for focusing or concentrating the ions of interest sdPittcon 2012 24
  • 47. Matrix Elimination IC Features (cont’d) Analysis in • Provides Chemistry the Second Dimension Using a Different – Enhanced sensitivity – For example, the cross-sectional area of a 1 mm column is one sixteenth the area of a 4 mm column, providing a sensitivity enhancement factor of ~16 Analysis in • Provides Chemistry the Second Dimension Using a Different – Enhanced selectivity • Easily Implemented on the ICS-3000/ICS-5000 System 25
  • 48. Matrix Elimination Ion Chromatography (MEIC) — Instrumental Setup 1st Dimension Pump waste 2nd Dimension Autosampler1 EG Injection Valve 1 Large Loop CRD 2 External Water Load Inject Diverter Valve Suppressor 2 waste Injection Valve 2 waste 1st Dimension Column (4 mm) CD 2 waste CD 1 External Water 2nd Dimension Column (2 mm) waste Suppressor 1 CRD 1 Concentrator Pump Column (UTAC-ULP1) Transfer to 2D Load Concentrator EG waste 26
  • 49. Effect of Matrix Concentration on Bromate Peak Shape and Recovery . IonPac® AG9-HC, AS9-HC, 4 mm Flow Rate: 1.0 mL/min Concentration: 9.0 mM Carbonate Suppressor: AAES Current: 58 mA Loop: 500 µL Oven: 30 °C Column: E 1 D 1 C 1 B Peaks: A Matrix Concentration: and SO4 1 1 4 Minutes 8 12 Bromate 0.005 mg/L A) 0 B) 50 C) 100 D)150 E) 200 ppm CI ppm CI and SO4 ppm CI and SO4 ppm CI and SO4 ppm CI and SO4 25633 27
  • 50. 2-D METHODS FOR DRINKING WATER • Using 4mm columns in the first dimension and 2 mm columns in the second dimension −EPA Method 302.0 for the analysis of bromate −EPA Method 314.2 for the analysis of perchlorate • Using 4mm columns in the first dimension and capillary columns in the second dimension in developmental stage −analysis of bromate −analysis of chromate −analysis of HAA5 28
  • 51. Sensitivity Flow Rate (mL/min) Sensitivity 1 1 Second (2 mm) 0.25 4 Second (0.4 mm) 0.01 100 Dimension First (4 mm) 29
  • 52. Determination of Trace Bromate in a Bottled Water Sample Using a 2-D Capillary RFIC System A. First-Dimension Conditions Column: IonPac® AG19, AS19, 4 mm Flow Rate: 1.0 mL/min Eluent: 10 to 60 mM KOH (EGC-KOH ) Suppressor: 4-mm SRS 300 Inj. Volume: 1000 µL Temperature: 30 °C Bromate 0.5 µS -0.3 1 17.0 —— —— —— —— B. Second-Dimension Conditions Column: AS20 (0.4 mm x 25 cm) Flow Rate: 10 µL/min Eluent: 35 mM KOH (EGC-KOH) Suppressor: Capillary Anion Suppressor Temperature: 30 °C Concentrator: Capillary concentrator, 2500 µL of 1st dimension suppressed effluent (7.5 to 10 minutes) Dionized water Brand A bottled water (54 ng/L) 100 ng/L bromate in deionized water 30 ng/L bromate in deionized water Minutes 20.0 30
  • 53. Conclusions • 2-D IC has met or exceeded all EPA requirements for robustness, precision and accuracy. • Published since 2005 as a compliance monitoring method. • 2-D IC has also been demonstrated for perchlorate EPA 314.2 • Capillary IC format in the second dimension is allowing ppt level detection for bromate. • A 2-D IC method for HAA5 is currently undergoing secondary lab validation studies. 31
  • 54. Comparison of EPA Methods 300.1, 317, 326 and 302 for Bromate Analysis Part 3 Richard F. Jack, PhD Manager, Global Market Development March 29, 2012
  • 55. EPA Method 302 2D-IC for Bromate Analysis First Dimension—Dionex IonPac AS19 Column 0.60 • EPA Method 300.1 can have low recoveries for high Cl samples • EPA Mehtod 317 uses a toxic, unstable reagent • EPA Method 326 is complicated, less robust µS • 2D-IC developed for 0.30 • Direct injection method Concentrator Second Dimension—Dionex IonPac AS24 Column 0.64 • Easy to use • Sensitivity • Matrix elimination BrO3 µS • EPA approved methods • EPA Method 302.0 bromate 0.54 0 10 20 Minutes 30 35 • EPA Method 314.2 perchlorate • EPA haloacetic acids (pending)
  • 56. New 2D Method Features • Allows for large loop injection in the first dimension (4 mm column) • Injection to a larger loop than the standard approach is possible since the capacity and selectivity of the analytical column in the first dimension dictates the recovery and the analyte of interest is analyzed in the second dimension. • Focus the ions of interest in a concentrator column after suppression in the first dimension. • Hydroxide eluent is suppressed to DI water, providing an ideal environment for focusing or concentrating the ions of interest. • Pursue analysis in the second dimension using a smaller column format operated at a lower flow rate, leading to sensitivity enhancement that is proportional to the flow rate ratio. • For a 4 mm column operated in the first dimension at 1 mL/min and a 1 mm column operated in the second dimension at 0.05 mL/min the enhancement factor is 20. • Easy implementation on the ICS-5000 system
  • 57. Schematic of a 2D-IC Configuration First Dimension Pump waste Second Dimension Autosampler 1 EG waste CD 2 Injection Valve 1 CRD 2 Large Loop External Water Load Inject Suppressor 2 Injection Valve 2 waste 4 mm Column 1 CD 1 2 mm Column 2 External Water waste Suppressor 1 CRD 1 Dionex IonPac UTAC-ULP1 Concentrator Column Pump Transfer to 2D Load Concentrator EG waste
  • 58. Sensitivity: Instrumental Configuration for Bromate Analysis by 2D-IC First Dimension - Large-loop injection - Partially resolve matrix Intermediate Step Large Loop Suppressor Pump EG 4 mm Column Injection Valve CRD Cell 2 Second Dimension - Resolve on smaller column - Sensitivity enhancement - Different selectivity optional Suppressor 0.4 mm Column - Remove time segment - Trap and concentrate Cell 1 ions of interest CRD Dionex IonPac UTAC-ULP1 Concentrator Column EG Switching Valve Pump
  • 59. 2D Analysis in High-Ionic-Strength Water First Dimension 0.60 Conditions: Column: Primary Secondary Dionex IonPac Dionex IonPac AS19, 4 mm AS24, 2 mm Flow Rate: 1.0 mL/min 0.25 mL/min Suppressor: Dionex ASRS Dionex ASRS ULTRA II 4 mm ULTRA II 2 mm Current: 161 mA 41 mA Loop: 1000 µL Concentrator: UTAC-ULP1, 5 x 23 mm Oven: 30 °C µS 0.30 0 Concentrator Second Dimension 0.64 BrO3 µS Peak: Matrix: 0.54 0 10 20 Minutes 30 35 Bromate 0.5 µg/L DI Water, high ionic water (EPA 300.1)
  • 60. 1D Bromate Analysis with Dionex IonPac AS19 Column Gradient Chemistry A. 5 ppb BrO3 Spiked with 250 ppm Cl, SO4 0.4 µS 1 –0.0 –0.1 0 5 10 15 Dionex IonPac AG19, AS19, 4 mm Flow Rate: 1.0 mL/min Suppressor: Dionex ASRS ULTRA II, 4 mm Current: 113 mA Loop: 500 µL Oven: 30 °C Column: 3 2 20 25 30 35 B. 5 ppb BrO3 in Reagent Water 0.4 2 3 Peaks: Bromate Chloride Sulfate µS 1 –0.0 –0.1 0 5 10 15 20 Minutes 25 30 35 A B 0.005 mg/L 0.005 mg/L 250 0.030 250 0.150
  • 61. 2D Bromate Analysis with Dionex IonPac AS19 Gradient Chemistry 0.4 A. 5 ppb BrO3 Spiked with 250 ppm Cl, SO4 Columns: µS 1 –0.1 0 5 10 15 20 25 30 0.4 B. 5 ppb BrO3 in Reagent Water A. Dionex IonPac AG19, AS19, 4 mm B. Dionex IonPac AG19, AS19, 2 mm Flow Rate: A. 1.0 mL/min B. 0.25 mL/min Suppressor: A. Dionex ASRS ULTRA II, 4 mm B. Dionex ASRS ULTRA II, 2 mm Current: A. 113 mA 35 B. 29 mA Loop: 500 µL Concentrator: TAC-ULP1 Peaks Bromate Chloride Sulfate µS 1 –0.1 0 5 10 15 20 Minutes 25 30 35 A 0.005 mg/L 250 250 B 0.005 mg/L 0.030 0.150
  • 62. Trace Analysis of Bromate in Bottled Water by 2D-IC Bromate 0.5 µS -0.3 1 17 —— —— —— —— Sample A (54 ng/L) 100 ng/L bromate in deionized water 30 ng/L bromate in deionized water Deionized water Minutes A. First Dimension Column: Dionex IonPac AG19, AS19, 4 mm Flow rate: 1 mL/min Eluent: 10–60 mmol/L KOH Eluent Source: Dionex EGC III KOH Suppressor: Dionex ASRS 300 (4 mm) Inj. volume: 1000 µL Temperature: 30 °C B. Second Dimension Column: Dionex IonPac AS20 (0.4 mm) Flow rate: 10 µL/min Eluent: 35 mmol/L KOH Eluent Source: Dionex EGC-KOH (Capillary) Suppressor: Thermo Scientific Dionex ACES 300 Anion Capillary Electrolytic Suppressor Temperature: 30 °C Concentrator: Capillary concentrator, 20 2500 µL of the suppressed effluate from the first dimension (7.5–10 min)
  • 63. Sensitivity Improvement • RFIC using hydroxide eluents suppressed to water, lower background • RFIC in 2D-IC 4/2 mm results in 4x sensitivity enhancement • 2D-IC in 4/0.4 mm format improves sensitivity 100x Dimension Sensitivity Flow Rate (mL/min) First (4 mm) 1 1 Second (2 mm) 4 0.25 100 0.01 Second (0.4 mm)
  • 64. Sensitivity: Instrumental Configuration for 2D-IC First Dimension - Large loop injection - Partially resolve analyte from matrix Load Inject Large Loop Pump EG Suppressor Column Injection Valve 1 4 mm Second Dimension - Separate on Cell 2 smaller ID column - Different selectivity - Signal enhancement Intermediate Step Cell 1 CRD CRD 4-mm 0.4-mm 2-mm Column Column Suppressor Pump Transfer to 2D Load Concentrator Concentrator Valve 2 EG - Separate Transfer cut volume - Trap and focus ions of interest
  • 65. Trace Perchlorate Using 2D-IC with Second Column in Capillary Format A. First Dimension Conditions First Dimension Chromatogram 0.1 µS Full Scale 0.10 µS Column: Flow rate: Eluent: Eluent Source: Suppressor: Inj. volume: Temperature: 1 Dionex IonPac AG16, AS16, 4 mm 1.0 mL/min 65 mM KOH Dionex EGC III KOH Dionex ASRS 300 4000 µL 30 °C B. Second Dimension Conditions 0.0 60 0 10.0 Second Dimension Chromatogram 10 µS Full Scale µS Column: Flow rate: Eluent: Suppressor: Temperature: Concentrator: 1 Peak: Dionex IonPac AS20, 0.4 mm 10 µL/min 35 mM KOH Dionex ACES™ 300 30 °C Capillary concentrator, 5000 µL of first dimension suppressed effluent (19–24 min) 1. Perchlorate 1.0 µg/L Perchlorate Peak Area 0.0 0 Minutes 60 First Dimension: Second Dimension: 0.0115 µS*min 1.75 µS*min Capillary IC provides a 100-fold increase in sensitivity!
  • 66. Trace Analysis of Perchlorate with 2D-IC 2.5 A. First Dimension Conditions Column: Dionex IonPac AG16, AS16, 4 mm Flow rate: 1.0 mL/min Eluent: 65 mmol/L KOH Eluent Source: Dionex EGC III KOH Perchlorate µS B. Second Dimension Conditions Column: Dionex IonPac AS20, 0.4 mm Flow rate: 10 µL/min Eluent: 35 mmol/L KOH —— Brand A bottled water (263 ng/L perchlorate) Eluent Dionex EGC-KOH —— Brand B bottled water (38.5 ng/L perchlorate) Source: (Capillary) —— 30 ng/L perchlorate in DI water —— DI water -1.0 30 Minutes 45
  • 67. Conclusion • The hydroxide-selective RFIC Dionex IonPac AS19 column was specifically developed for the determination of trace bromate and other disinfection byproduct anions in drinking and bottled water. • It can be successfully used in place of the Dionex IonPac AS9-HC for validating EPA Methods 300.1 (B), 317, and 326. • A RFIC system and a Dionex IonPac AS19 column improves the determination of bromate by increasing: • Sensitivity • System automation • Ease of use • The use of 2D-IC preserves performance even in high-matrix samples. * U.S. EPA Office of Water, Nov. 19, 2002