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

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)

Drinking Water Disinfection: Treatment and Byproducts

Disinfection Treatment

Disinfection Byproducts

Chlorination Trihalomethanes Haloacetic Acids

Chlorate

Chlorine Dioxide Chlorite Chlorate

Chloramine Chlorate

Ozonation Bromate

Disinfection byproducts are formed when disinfectants used in water treatment plants react with bromide and/or natural organic matter.

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

EPA Bromate Method Summary

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

IC Suppressed Conductivity

300.0 (B)

Dionex Ion Pac AS9-HC

AS23 AS19

Carbonate Carbonate Hydroxide

Conductivity 5.0 0 1.63 0.32

IC-Suppressed Conductivity

300.1

Dionex IonPac AS9-HC

AS23 AS19

Carbonate Carbonate Hydroxide

5.0 0 1.63 0.32

2D-IC Suppressed Conductivity

302.0a Dionex IonPac AS19, 4 mm AS24, 2 mm

Hydroxide

0.036

IC Suppressed Conductivity with Postcolumn ODA

317.0 Dionex IonPac

AS9-HC AS19

Carbonate Hydroxide

Conductivity UV

0.32 0.14

IC Suppressed Conductivity with Postcolumn Acidified KI

326.1 Dionex IonPac

AS9-HC AS19

Carbonate Hydroxide 0.29 0.17

IC-ICP-MS 321.8 Dionex CarboPac PA100 0.01

Bromate Method, Application Note and Matrix Recommendations

Technique EPA Method

Application Note Matrix


300.0 (B) 167, 184 Low salt conditions


300.1 167, 184 Low salt conditions

IC Suppressed Conductivity with Postcolumn ODA

317.0 168 Tolerates higher salt conditions



2D-IC Suppressed Conductivity


IC-ICP-MS 321.8 Tolerates higher salt conditions

Bromate Method, Application Note and Matrix Recommendations (cont’d)

Technique Method Application Note Matrix

IC Chemically Suppressed Conductivity

ISO 15061, ASTM 6581 167, 184

Drinking water only, ground- and wastewater only if low salt conditions


ISO Pending 171 Tolerates higher salt conditions.

IC Suppressed Conductivity with Postcolumn Acidified KBr

Japan Tolerates higher salt conditions.

Bromate Regulations and Methods Timeline

1993: WHO MCL 25 ppb 1998:

U.S. EPA MCL of 10 ppb EU MCL 50 to 10 ppb

2003: WHO MCL 10 ppb

2004: U.S. stage II DBP Rule MCLG “0” U.S. FDA regulates in BW

1995: AN 101 Carbonate 2004: AN 136

Carbonate, Postcolumn ODA, AN 167 Hydroxide, Dionex IonPac AS19

2003: AN 149 Carbonate, Postcolumn I3

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

2000: EPA 317

2002: EPA 326 2009: EPA 302

2009: AN 208 Carbonate, CRD Dionex IonPac AS23

1993: EPA 300.0 1997: EPA 300.1

Columns: A. Dionex IonPac AG9-SC, AS9-SC B. Dionex IonPac AG9-HC, AS9-HC

Eluent: A. 1.8 mM Sodium carbonate 1.7 mM Sodium bicarbonate B. 9.0 mM Sodium carbonate Flow Rate: 1 mL/min Inj. Volume: 25 µL Detection: Suppressed Conductivity, Thermo Scientific Dionex ASRS Anion Self- Regenerating Suppressor,Thermo Scientific Dionex AutoSuppression device, external water mode

Peaks: 1. Fluoride 3.0 mg/L 2. Chlorite 10.0 3. Bromate 20.0 4. Chloride 6.0 5. Nitrite 15.0 6. Bromide 25.0 7. Chlorate 25.0 8. Nitrate 25.0 9. o-Phosphate 40.0 10. Sulfate 30.0

B

A

0 5 10 15 20 25

0

10

Minutes

µS

1

2 3

4

5 6

7 8

9

10

1

2 3

4 5

6 7

8 9 10

0

14

µS

EPA 300.1 Comparison of Dionex IonPac AS9-SC and AS9-HC Columns for Oxyhalide Determination

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 Peak 1: Bromate 0.005 mg/L Matrix Concentration: E 200 ppm of CI and SO4 D 150 C 100 B 50 A 0

Effect of Matrix Concentration on Bromate Peak Shape and Recovery

0 4 8 12

1

1

1

1

1

A

B

C

D

E

Minutes

µS

System Configuration EPA Methods 300.1 and 317 for Bromate

Pump Guard Suppressor

Conductivity Detector

PCR Reservoir

ODA Mixing

Tee

Absorbance Detector

Separation

EPA Methods 300.1 and 317 for Trace Bromate Column: Dionex IonPac AG9-HC, AS9-HC (4 × 250 mm) Eluent: 9.0 mM Sodium carbonate Flow Rate: 1.3 mL/min Inj. Volume: 225 mL Detection: A) Suppressed conductivity Dionex ASRS™ ULTRA, Dionex AutoSuppression™

external water mode B) Absorbance, 450 nm Postcolumn Reagent: o-dianisidine PCR Flow Rate: 0.7 mL/min Postcolumn Heater: 60 °C Peaks: 1. Chlorite 20 mg/L (ppb) 2. Bromate 5 3. Surrogate (DCAA) 1000 4. Bromide 20 5. Chlorate 20 Chromatograms courtesy of Herb Wagner, U.S. EPA.

0.25 3

10 0 5 15 20

0

(A)

1 2

4 5

µS

Method 300.1

0.015

Minutes 10 0 5 15 20

0

(B)

2 1 AU

Method 317.0

System Configuration for EPA Method 300.1 and 326.0 for Trace Bromate

Thermo Scientific Dionex AMMS

MicroMembrane Suppressor

KI→HI

Pump Suppressor

Conductivity Detector

PC10 PCR Reservoir

KI

Mixing Tee

Absorbance Detector

Knitted RX Coil PCH-2 Heater

Waste

BrO3– + HI → I3

Color (352) nm)

Guard Separation

Cation-Exchange Membrane

Details of Postcolumn Reagent Generation with Dionex AMMS™ III

300 mM Sulfuric Acid To Mixing Tee

Waste

K+ HSO4–

Cation-Exchange Membrane

Waste

K+ HSO4–

K+

H+ HSO4– H+ HSO4

–

300 mM Sulfuric Acid

K+

H+ H+

From PC10

H+ + I–

I–

I–

KI

Bromate Oxidizes Iodide to Triiodide in EPA Method 326 through Postcolumn Reaction

Mixing Tee KI + H+ from Dionex AMMS

Bromate from Column

BrO3– + 3I– + 3H+

3HOI + 3I– + 3H+

3I2– + 3I–

3HOI + Br– 3I2 + 3H2O 3I3–

I3–

Detect I3– at 352 nm

Analysis of Bromate and Common Anions in Bottled Water

Column: Dionex IonPac AG9-HC, AS9-HC, 4 mm Eluent: 9.0 mM Sodium carbonate Temp: 30 °C Flow Rate: 1.3 mL/min Inj. Volume: 225 µL Detection: A) Suppressed conductivity, Dionex AAES Anion Atlas™ Electrolytic Suppressor, external water mode B) Absorbance, 352 nm Postcolumn Reagent: Acidified KI PCR Flow Rate: 0.4 mL/min Postcolumn Heater: 80 °C

Peaks: A) Conductivity 1. Chlorite not detected 2. Bromate 1.52 µg/L (ppb) 3. DCA* 4. Bromide 1.12 5. Chlorate 1.08

B) Postcolumn Reagent/UV 2. Bromate 1.84 µg/L (ppb)

* DCA = Dichloroacetate quality control surrogate

–0.001

0.004

26.10

27.10

0 5 10 20 15

0 5 10 20 15 Minutes

(A)

(B)

AU

2

3

4

5

2

µS

Method 300.1

Method 326.0

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

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

Chromatogram of Mineral Water A Spiked with 1 µg/L Each Chlorite and Chlorate and 0.5 µg/L Bromate

Column: Dionex IonPac AG19, AS19 4 mm Eluent: 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

Peaks: 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

30 25 20 15 10 5 0

Minutes

0.2

0.5

µS

1 4 8 9 10

1

2 3

11

Hydroxide vs Carbonate Eluents for Separation of Common Anions and DPBs in Mineral Water

• 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.

Column: A) Dionex IonPac AS19 B) Dionex IonPac AS23 Eluent: A. Hydroxide B. Carbonate/bicarbonate Detection: Suppressed conductivity

Peaks A B 1. Fluoride 2. Chlorite 8.8 11.3 µg/L 3. Bromate 4.7 5.1 4. Chloride 5. Nitrite 6. Chlorate 13.5 9.5 7. Bromide 8. Nitrate 9. Carbonate 10. Sulfate 11. Orthophosphate

0.2

0.5

µS

1

2 3

A

0 5 10 15 20 25 30 -0.1

0.7

µS

1

2

3

B 4

5 6 7

9

8

4

5 6

7

8 9

11 10

10 11

Minutes

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 See Application Note 184 for conditions b RSD = relative standard deviation, n = 7 c Quality control standard contained 10 ppb each of chlorite, chlorate, and bromide and 5 ppb bromate

Resolution and Sensitivity Improvement with Hydroxide Eluent + Gradient Separation

µS

–0.5

3.0 Chloride (Dionex IonPac AS18 column, hydroxide) Area: 0.2743 µS•min Height: 2.98 µS Plates: 22,843 EP

µS

–0.5

2.0

0

0

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

1 min

1 min

Affect of Cl Concentration on Bromate Recovery Using a Dionex IonPac AS19 Column

0

20

40

60

80

100

Bromate Recovery

0 50 100 150 250 200

Cl conc (ppm)

% RSD

1

Part 2: Quality Assurance Requirements for EPA Method Development

Herbert P. Wagner, Analytical Chemist March 29, 2012

Comparison of EPA Methods 300.1, 317, 326 and 302 for

Bromate Analysis

2

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

3

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.

4


• 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.

5


• 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

6


• 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).

8


• 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.

9


• 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).

10

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.

11

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.

12


• 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.

13


• 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.

14


• 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.

15


• 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.

16


• 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.

17

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


6 Sample 2 LFSM Recovery of 80–120%

7 Sample 2 LFSMD % RPD = ± 20%






18

Analysis Batch Sequence (Cont’d)

Injection # Sample Description Acceptance Criteria 13 Sample 8 Normal Analysis 14 Sample 9 Normal Analysis


16 CCC at Mid Level Recovery of 80–120%


18 Sample 12 Normal Analysis 19 Sample 13 Normal Analysis 20 Sample 14 Normal Analysis





19

Analysis Batch Sequence (Cont’d)

Injection # Sample Description Acceptance Criteria



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

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

– 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

EPA Method 302.0 Two-Dimensional Matrix Elimination IC (cont.)

22

Current Approaches in IC Trace Analysis

• Samples with Low Levels of Matrix Ion – Analysis is typically performed using pre-

concentration 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

23

Current Approaches in IC Trace Analysis (cont’d)

• Samples with High Levels of Matrix Ions – Requires a sample pretreatment step using solid-

phase 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

24

Matrix Elimination Ion Matrix Elimination Ion Chromatography (MEIC) FeaturesChromatography (MEIC) Features•• Allows LargeAllows Large--Loop Injection in the First Dimension Loop Injection in the First Dimension

(4 mm column)(4 mm column)–– Possible to inject a larger loop volume than the Possible to inject a larger loop volume than the

standard approach because the capacity and standard approach because the capacity and selectivity of the analytical column in the first selectivity of the analytical column in the first dimension dictates the recovery, and the analyte dimension dictates the recovery, and the analyte of interest is analyzed in the second dimensionof interest is analyzed in the second dimension

•• Focuses Ions of Interest in a Concentrator Column Focuses Ions of Interest in a Concentrator Column After Suppression in the First DimensionAfter Suppression in the First Dimension–– Hydroxide Hydroxide eluenteluent converted to DI water, providing converted to DI water, providing

an ideal environment for focusing or an ideal environment for focusing or concentrating the ions of interestconcentrating the ions of interest

PittconPittcon 20122012sd

25

Matrix Elimination IC Features (cont’d)

•• Provides Analysis in the Second Dimension Using a Provides Analysis in the Second Dimension Using a Different ChemistryDifferent Chemistry–– Enhanced sensitivityEnhanced sensitivity–– For example, the crossFor example, the cross--sectional area of a 1 mm sectional area of a 1 mm

column is one sixteenth the area of a column is one sixteenth the area of a 4 mm column, providing a sensitivity enhancement 4 mm column, providing a sensitivity enhancement factor of ~16 factor of ~16

•• Provides Analysis in the Second Dimension Using a Provides Analysis in the Second Dimension Using a Different ChemistryDifferent Chemistry–– Enhanced selectivityEnhanced selectivity

•• Easily Implemented on the ICSEasily Implemented on the ICS--3000/ICS3000/ICS--5000 System5000 System

26

Pump

Injection Valve 1

Suppressor 1

CD 1

Injection Valve 2

Autosampler1

Load Inject

Transfer to 2D Load Concentrator

Large Loop

1st Dimension Column (4 mm) 2nd Dimension Column (2 mm)

Suppressor 2

CD 2

Concentrator

Column (UTAC-ULP1)

EG

1st Dimension 2nd Dimension

CRD 1

CRD 2

External Water

waste

waste

waste

External Water

waste

waste

Pump EG

Diverter Valve

waste

Matrix Elimination Ion Chromatography (MEIC) — Instrumental Setup

27

Effect of Matrix Concentration on Bromate Peak Shape and Recovery .

Column: IonPac® AG9-HC, AS9-HC, 4 mm

Flow Rate: 1.0 mL/minConcentration:9.0 mM CarbonateSuppressor: AAESCurrent: 58 mALoop: 500 µLOven: 30 °C

Peaks: Bromate 0.005 mg/L

Matrix Concentration: A) 0 ppm CI and SO4

B) 50 ppm CI and SO4C) 100 ppm CI and SO4D)150 ppm CI and SO4E) 200 ppm CI and SO4

4 8 12

1

1

1

1

1

A

B

C

D

E

Minutes

25633

28

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

29

Sensitivity

Dimension Flow Rate (mL/min) Sensitivity

First (4 mm) 1 1

Second (2 mm) 0.25 4

Second (0.4 mm) 0.01 100

30

Determination of Trace Bromate in a Bottled Water Sample Using a 2-D Capillary RFIC

System

—— Dionized water—— Brand A bottled water (54 ng/L)—— 100 ng/L bromate in deionized water—— 30 ng/L bromate in deionized water

17.0 20.0 -0.3

0.5

µS

Minutes

1

Brom

ate

A. First-Dimension ConditionsColumn: 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 µLTemperature: 30 °C

B. Second-Dimension ConditionsColumn: AS20 (0.4 mm x 25 cm)Flow Rate: 10 µL/minEluent: 35 mM KOH (EGC-KOH)Suppressor: Capillary Anion SuppressorTemperature: 30 °CConcentrator: Capillary concentrator,

2500 µL of 1st dimension suppressed effluent (7.5 to 10 minutes)

31

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.

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

EPA Method 302 2D-IC for Bromate Analysis

• 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

• 2D-IC developed for • Direct injection method • Easy to use • Sensitivity • Matrix elimination

• EPA approved methods

• EPA Method 302.0 bromate • EPA Method 314.2 perchlorate • EPA haloacetic acids (pending)

0.30

0.60

µS

0 10 20 30 35 0.54

0.64

µS BrO3

Minutes

Concentrator

First Dimension—Dionex IonPac AS19 Column

Second Dimension—Dionex IonPac AS24 Column

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

Schematic of a 2D-IC Configuration

Pump

Injection Valve 1

Suppressor 1

CD 1

Injection Valve 2

Autosampler 1

Load Inject


Large Loop

4 mm Column 1 2 mm Column 2

Suppressor 2

CD 2

Dionex IonPac UTAC-ULP1 Concentrator Column

EG

First Dimension Second Dimension

CRD 1

CRD 2 External Water

waste

waste

waste

External Water

waste

waste

Pump EG

Sensitivity: Instrumental Configuration for Bromate Analysis by 2D-IC

Large Loop Suppressor

Cell 1 Pump EG 4 mm

Column Injection Valve

CRD

Switching Valve

0.4 mm Column

Dionex IonPac UTAC-ULP1 Concentrator Column

Pump Cell 2

Suppressor

CRD

First Dimension - Large-loop injection - Partially resolve matrix Intermediate Step

- Remove time segment - Trap and concentrate ions of interest

Second Dimension - Resolve on smaller column - Sensitivity enhancement - Different selectivity optional

EG

2D Analysis in High-Ionic-Strength Water

0.30

0.60

µS

0

0 10 20 30 35 0.54

0.64

µS BrO3

Minutes

Concentrator

First Dimension

Second Dimension

Peak: Bromate 0.5 µg/L Matrix: DI Water, high ionic water (EPA 300.1)

Conditions: Primary Secondary Column: 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

1D Bromate Analysis with Dionex IonPac AS19 Column Gradient Chemistry

A. 5 ppb BrO3 Spiked with 250 ppm Cl, SO4

B. 5 ppb BrO3 in Reagent Water

Column: 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 Peaks: A B Bromate 0.005 mg/L 0.005 mg/L Chloride 250 0.030 Sulfate 250 0.150

2 3

–0.1

–0.0

0.4

µS

1

0 5 10 15 20 25 30 35

–0.1

–0.0

0.4

µS

1

2 3

Minutes 0 5 10 15 20 25 30 35

A. 5 ppb BrO3 Spiked with 250 ppm Cl, SO4

B. 5 ppb BrO3 in Reagent Water

Columns: 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 B. 29 mA

Loop: 500 µL Concentrator: TAC-ULP1 Peaks A B Bromate 0.005 mg/L 0.005 mg/L Chloride 250 0.030 Sulfate 250 0.150

–0.1

0.4

µS

1

–0.1

0.4

µS

1

Minutes 0 5 10 15 20 25 30 35

0 5 10 15 20 25 30 35

2D Bromate Analysis with Dionex IonPac AS19 Gradient Chemistry

Trace Analysis of Bromate in Bottled Water by 2D-IC

—— Sample A (54 ng/L) —— 100 ng/L bromate in deionized water —— 30 ng/L bromate in deionized water —— Deionized water

17 20 -0.3

0.5

µS

Minutes

1

Bro

mat

e

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, 2500 µL of the suppressed effluate from the first dimension (7.5–10 min)

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 Second (0.4 mm) 100 0.01

Large Loop

Suppressor Cell 1

Pump EG

4 mm Injection Valve 1 CRD

Column

Valve 2 EG

4-mm Column

Concentrator

Pump

Cell 2 Suppressor

CRD

First Dimension - Large loop injection - Partially resolve analyte from matrix Intermediate Step

- Separate Transfer cut volume - Trap and focus ions of interest

Load Inject


2-mm Column

Sensitivity: Instrumental Configuration for 2D-IC

Second Dimension - Separate on smaller ID column - Different selectivity - Signal enhancement

0.4-mm Column

Trace Perchlorate Using 2D-IC with Second Column in Capillary Format

0.0

0.10

µS

0 60 0.0

10.0

µS

Minutes

First Dimension Chromatogram

0.1 µS Full Scale

Second Dimension Chromatogram 10 µS Full Scale

A. First Dimension Conditions Column: Dionex IonPac AG16, AS16, 4 mm Flow rate: 1.0 mL/min Eluent: 65 mM KOH Eluent Source: Dionex EGC III KOH Suppressor: Dionex ASRS 300 Inj. volume: 4000 µL Temperature: 30 °C B. Second Dimension Conditions Column: Dionex IonPac AS20, 0.4 mm Flow rate: 10 µL/min Eluent: 35 mM KOH Suppressor: Dionex ACES™ 300 Temperature: 30 °C Concentrator: Capillary concentrator, 5000 µL of first dimension suppressed effluent (19–24 min) Peak: 1. Perchlorate 1.0 µg/L Perchlorate Peak Area First Dimension: 0.0115 µS*min Second Dimension: 1.75 µS*min

0 60

1

1

Capillary IC provides a 100-fold increase in sensitivity!

Trace Analysis of Perchlorate with 2D-IC

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 B. Second Dimension Conditions Column: Dionex IonPac AS20, 0.4 mm Flow rate: 10 µL/min Eluent: 35 mmol/L KOH Eluent Source: Dionex EGC-KOH (Capillary)

30 45 -1.0

2.5

µS

Minutes

Perchlorate

—— Brand A bottled water (263 ng/L perchlorate) —— Brand B bottled water (38.5 ng/L perchlorate) —— 30 ng/L perchlorate in DI water —— DI water

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

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

Technology

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