Ion Chromatography: Green Chemistry for a Green...
Transcript of Ion Chromatography: Green Chemistry for a Green...
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
ThermoFisher is committed to IC Environmental Methods