Quick and Effective Extraction of Perfluorinated in water ... · Chicago Regional Laboratory, nor...

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Quick and Effective Extraction of PerfluorinatedCompounds (PFCs) in water/sludge/soil/biosolidSamples Followed by UPLC/MS/MS Analysis

Mention of Vendor Names Does Not Constitute Product Endorsement

Dr. Lawrence B. Zintek, Dr. Babina Shrestha, Chhavi Bhardwaj, Dennis J. Wesolowski

US EPA Region 5 Chicago Regional Laboratory

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Disclaimer

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States government.

The views and opinions of author expressed herein do not necessarily state or reflect those of the United States government or United States Environmental Protection Agency and shall not be used for advertising or product endorsement purposes.

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Disclaimer Continued

This work was sponsored by an agency of the United States government. Neither the United States government nor US EPA Region 5 Chicago Regional Laboratory, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness,or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.

Introduction

• Why involved?• Published methods on PFCs

– Many methods have laborious extraction and clean‐up procedures that limit sample throughput for a small operation.

• Tailor the methods to our customers needs.• Reporting limits‐ don’t require drinking water reporting levels.• Broad matrices‐ influents, effluents, sludge, biosolids, soil….• Probably many samples

• Method development for the quicker extraction and analysis of fluorinated chemicals from waters, sludge, biosolids and soils.

• To quantify and evaluate the levels of contaminants of emerging concern (CEC) based on biosolid/sludge/soil treatments

Dream Job

Target List• Perfluoroalkyl Sulfonates (PFAS) :• Perfluorobutyl Sulfonates (PFBS) C4F9 SO3

• Perfluorohexyl Sulfonate (PFHxS) C6F13 SO3

• Perfluorooctyl Sulfonate (PFOS) C8F17 SO3

• Decafluoro 4 (pentafluoroethyl)cyclohexane Sulfonate (PFechS) C8F14SO3

• Perfluoroalkyl Carboxylates (PFCA)• Perfluorobutonoate (PFBA) – C4F7O2

‐

• Perfluoropentonoate (PFPeA) – C5F9O2‐

• Perfluorohexonoate (PFHxA) – C6F11O2‐

• Perfluoroheptonoate (PFHpA) – C7F13O2‐

• Perfluorooctonoate (PFOA) – C8F15O2‐

• Perfluorononanoate (PFNA) – C9F17O2‐

• Perfluorodecanoate (PFDA) – C10F19O2‐

• Perfluoroundecanoate (PFUnA) – C11F21O2‐

• Perfluorododecanoate (PFDoA) – C12F23O2‐

• Perfluorotridecanoate (PFTriA) – C13F25O2‐

• Perfluorotetradecanoate (PFTreA) – C14F27O2‐

Target List‐ FTOHs

• 4:2 FTOH (C4F9CH2CH2OH)• 6:2 FTOH (C6F13CH2CH2OH) • 8:2 FTOH (C6F13CH2CH2OH) • 7:2s FTOH (C9H5F15O) • 10:2 FTOH (C8F17CH2CH2OH)

A few more added…

• FHEA‐ 2‐Perfluorohexyl ethanoic acid• F0EA‐ 2‐Perfluorooctyl ethanoic acid• FDEA‐ 2‐Perfluorodecyl ethanoic acid• FHUEA‐ 2H‐Perfluoro‐2‐octenoic acid• FOUEA‐ 2H‐perfluoro‐2‐decenoic acid• FHpPA‐ 3‐Perfluoroheptyl propanoic acid

Determine Chromatographic Parameters and Detection Levels

• Liquid Chromatography – PFAS/PFCA‐ ACQUITY UPLC® CSH™ Phenyl‐Hexyl1.7 m, 2.1 x 100 mm column

• CSH™‐ “Charged Surface Hybrid” Particle

– FTOHs‐ ACQUITY UPLC® BEH C18 1.7 m, 2.1 x 100 mm column

• Detector‐MS/MS – Xevo® TQ‐S

Workhorses

Column Life with the “dirty” Samples

• Same column used for all the “888” injections‐effluents, influents, soils, biosolids, sludge.

• Column performing same today as it did when new.

PFAS/PFCA Gradient and Calibration

Time (min)

Flow

(L/min)95% Water: 5%

Acetonitrile Acetonitrile

400 mM Ammonium Acetate (95% water: 5%

Acetonitrile)0 300 95 0 51 300 75 20 56 300 50 45 513 300 15 80 514 300 0 95 517 300 0 95 518 300 95 0 520 300 95 0 5

ACQUITY UPLC® CSH™ Phenyl‐Hexyl 1.7 m, 2.1 x 100 mm column

Calibration Curve: 1‐ 100 ppt or 5‐ 500 ppt

PFAS/PFCA Level 1 of Calibration Curve‐100 L Injection‐50%Water/50% MeOH, 0.1%

Acetic Acid

• 1 ppt– Most

• 5 ppt– PFBA, PFPeA, PFTriA, PFTreA

• In Process*‐ Low ppt– FHEA, FOEA, FDEA

• At least 2 transitions except for PFBA, PFPeAFHUEA and FOUEA

Calibration Level‐ 5 ppt05-Feb-201417:11:54

Time4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

%

0

100020414Level1 15: MRM of 3 Channels ES-

713 > 669 (PFTreA669)2.31e4

10.8510.5010.92

11.18

020414Level1 15: MRM of 3 Channels ES- 713 > 169.1 (PFTreA169)

4.91e310.87

10.75

10.92

11.20

020414Level1 14: MRM of 3 Channels ES- 663 > 619 (PFTriA619)

3.48e410.37

10.08 10.52

020414Level1 14: MRM of 3 Channels ES- 663 > 169.1 (PFTriA169)

5.47e310.21

10.4210.44

020414Level1 2: MRM of 1 Channel ES- 263.1 > 219.1 (PFPeA)

3.70e44.76

4.694.50

4.814.85 5.40 5.47

020414Level1 1: MRM of 1 Channel ES- 213.1 > 169.1 (PFBA169)

1.62e43.72

3.663.37

4.404.29

020414Level3c 2: MRM of 1 Channel ES- 263.1 > 219.1 (PFPeA)

5.12e44.68

4.56 4.745.28 5.36

020414Level3c 1: MRM of 1 Channel ES- 213.1 > 169.1 (PFBA169)

3.06e43.70

3.653.35 4.294.22 4.35 20 uL Injection

20 uL InjectionPFBA and PFPeA better at 20 L Injection with raised reporting limits

PFTreA

PFTriA


Time5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100

5.50 5.75 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75

%

0

100020614Level1b 8: MRM of 2 Channels ES-

461 > 381.1 (PFechS381)3.11e4

8.10 8.20

020614Level1b 9: MRM of 2 Channels ES- 463.1 > 419.1 (PFNA419)

2.95e48.06

7.647.58 7.71 7.96 8.28 8.40

020614Level1b 6: MRM of 2 Channels ES- 399 > 80.1 (PFHxS80)

6.47e37.63

7.487.45

020614Level1b 7: MRM of 2 Channels ES- 413.1 > 369.1 (PFOA369)

2.87e47.35

7.32

7.307.177.08

7.37

7.39 7.737.59 7.76

020614Level1b 5: MRM of 2 Channels ES- 363 > 169.1 (PFHpA169)

4.84e36.596.57

6.55

6.326.43

6.60

6.62 6.77 6.91 7.13 7.18

020614Level1b 3: MRM of 2 Channels ES- 299 > 80.1 (PFBS80)

9.51e35.81

5.78

5.715.60

5.835.89

5.91 6.336.17

020614Level1b 4: MRM of 2 Channels ES- 313 > 269.1 (PFHxA269)

1.45e46.475.725.70

5.46 5.53

6.375.74

6.355.76 6.256.14PFHxA

PFBS

PFHpA

PFOA

PFHxS

PFNA

PFechS


Time8.60 8.80 9.00 9.20 9.40 9.60 9.80 10.00 10.20

%

0

100

8.60 8.80 9.00 9.20 9.40 9.60 9.80 10.00 10.20

%

0

100

8.60 8.80 9.00 9.20 9.40 9.60 9.80 10.00 10.20

%

0

100

8.60 8.80 9.00 9.20 9.40 9.60 9.80 10.00 10.20

%

0

100020614Level1b 13: MRM of 3 Channels ES-

613.1 > 569.1 (PFDoA569)1.79e4

9.869.84

9.83

9.81

9.819.679.619.42 9.52

9.87

9.87

9.88

10.209.94 10.139.95 10.32

020614Level1b 12: MRM of 3 Channels ES- 563 > 519 (PFUnA519)

2.99e49.28

9.28

9.209.179.08

9.32

9.339.44 9.53 9.769.55 9.70

020614Level1b 10: MRM of 2 Channels ES- 499 > 80.1 (PFOS80)

5.34e39.05

8.838.82

8.54

8.868.91

9.07

9.30

020614Level1b 11: MRM of 3 Channels ES- 513.1 > 469.1 (PFDA469)

2.92e48.718.69

8.508.40 8.57

8.74

8.978.80 8.90 9.139.00

PFDA

PFOS

PFUnA

PFDoA

FTOH Gradient and Calibration

Acquity UPLC® BEH C18 1.7 m, 2.1 x 100 mm column

Time (min)Flow

(µL/min)95% Water: 5%

Methanol95% Methanol: 5%

Water

100mM Ammonium Hydroxide (95% Water:

5% Methanol)0 300 95 0 51 300 95 0 53 300 75 20 55 300 50 45 56 300 20 75 59 300 0 95 513 300 0 95 514 300 95 0 516 300 95 0 5

FTOHs/Concentrations (µg/L)

Level 1 Level 2 Level 3 Level 4 Level 5 Level 6 Level 7 Level 8

4:2 FTOH 10 20 40 60 100 150 200 250

6:2 FTOH 1 2 4 6 10 15 20 25

8:2 FTOH, 7:2s FTOH and 10:2 FTOH

0.5 1 2 3 5 7.5 10 12.5

Calibration Level 1‐ FTOHs13-Jan-201417:03:49

Time8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100

8.50 9.00 9.50 10.00 10.50 11.00 11.50 12.00 12.50

%

0

100101315ftohLev1 5: MRM of 3 Channels ES-

563.1 > 503.1 (10:2FTOH2)3.27e4

11.74

11.6411.4111.25 12.5912.1411.92 12.82

101315ftohLev1 5: MRM of 3 Channels ES- 563.1 > 455.1 (10:2FTOH)

3.09e411.74

11.5011.2111.85 12.28 12.50 12.74 12.85

101315ftohLev1 4: MRM of 3 Channels ES- 463.2 > 403.1 (8:2FTOH2)

1.80e410.93

10.8910.72

10.9511.16

101315ftohLev1 4: MRM of 3 Channels ES- 463.2 > 355.1 (8:2FTOH)

1.88e410.92

10.8910.70

10.9611.17

101315ftohLev1 3: MRM of 2 Channels ES- 393.1 > 333.1 (FTOH7:2Sc)

4.63e410.59

10.48 10.65

101315ftohLev1 3: MRM of 2 Channels ES- 393.1 > 219.1 (FTOH7:2S)

4.09e510.59


2.30e39.999.96

9.739.61 10.0110.10


7.20e39.98

9.959.939.61 10.02

10.26

101315ftohLev1 1: MRM of 3 Channels ES- 263.1 > 203.1 (4:2 FTOH2)

2.92e39.059.00

8.898.388.28 8.549.09 9.279.43

500 ppt

500 ppt

500 ppt

1 ppb

10 ppb

10:2 FTOH

8:2 FTOH

7:2s FTOH

6:2 FTOH

4:2 FTOH

PFAS/PFCA Water Sample Preparation

• 5 mL water sample• Add “Spikes”

– Wellington MPFAC‐MXA• Labeled PFBA, PFHxA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFHxSand PFOS

• Add 5 mL MeOH• Shake• Filter through Polypropylene Filter Unit

– Pall Acrodisc® 25 mm Syringe Filter, with GxF/0.2m GHP Membrane

• Add 50 L formic acid• Analyze‐ 20 L or 100 L injection

– 100 L‐ Reporting Limits‐ 2 or 10 ppt

PFAS/PFCA Sludge Sample Preparation

• 5 mL Sludge sample• Add “Spikes”

– Wellington MPFAC‐MXA• Labeled PFBA, PFHxA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFHxS and PFOS

• Add 5 mL MeOH• Add 1 drop NH4OH, Shake, check if basic, pH 9‐10. • Tumble‐ 30 minutes• Centrifuge• Decant the liquid and filter through Polypropylene Filter Unit• Add 50 L formic acid• Analyze‐ 20 L or 100 L injection

– 100 L‐ Reporting Limits‐ 2 or 10 ng/L (PFBA, PFPeA, PFTriA, PFTreA)– 20 L‐ Reporting Limits‐ 10 or 50 ng/L (PFBA, PFPeA, PFTriA, PFTreA)

FTOHs Sludge Sample Preparation• Laboratory control samples (LCS) and method blank (MB) samples were

prepared in DI water.• 5 ml of sample was added to 15 ml polypropylene centrifuge tubes. • Laboratory control sample (LCS) and matrix spike (MS) samples were

spiked with 100 l of matrix spike solution containing 10 µg/ml (4:2 FTOH), 1 µg/ml (6:2 FTOH) and 0.5 µg/ml (8:2, 7:2s and 10:2 FTOHs).

• 5 ml of acetonitrile was then added to all samples and hand shaken/vortexed for ~ 1 minute.

• pH of the samples were adjusted to pH~10 with ammonium hydroxide (1 drop) and hand shaken/vortexed again for ~ 1 minute.

• The sample tubes were tumbled on a rotator for 2 hrs, then centrifuged at 1900 rpm for 10 min.

• The supernatant of all the samples and QC were filtered through AcrodiscGxF/0.2µm GHP membrane syringe driven filter unit to remove particulates.

PFAS/PFCA Soil/Biosolid Sample Preparation

• 2 gram sample• Add “Spikes”

– Wellington MPFAC‐MXA• Labeled PFBA, PFHxA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFHxS and PFOS

• 10 ml of methanol:water (50:50) ‐shake/vortex for ~ 2 minutes.• Add 1 drop NH4OH, shake/vortex for ~ 2 minutes, check if basic, pH

9‐10. • Tumble for 1 hr • Centrifuge• Decant the liquid and Filter through Polypropylene Filter Unit• Add 50 L formic acid• Analyze‐ 20 L Injection

– Reporting Limits‐ 25 ng/Kg or (125 ng/Kg PFBA, PFPeA, PFTriA, PFTreA)

NC Sludge Sample Before Extraction

NC Sludge Sample After Extraction

Sludge samples

Sludge Matrix SamplesSludge Samples Biosolid Sample

Fairfield reactor 1 (FFW1)Fairfield reactor 2 (FFW2)

Little Miami 1(LMW1)Little Miami 2 (LMW2)

Little Miami with Supplemental Sewage 1 (LMWSS1)

Little Miami with Supplemental Sewage 2 (LMWSS2)

Fairfield No Supplemental Sewage 1 (FFNSS1)

Fairfield No Supplemental Sewage 2 (FFNSS2)

Little Miami No Supplemental Sewage 1 (LMNSS1)

Little Miami No Supplemental Sewage 2 (LMNSS2)

Fairfield with Supplemental Sewage 1 (FFWSS1)

Fairfield with Supplemental Sewage 2 (FFWSS2)

Fairfield biosolid sample (FFBS)

SludgeRecovery Results

ChemicalMethod

Reporting Limits (ng/L) Transition

Laboratory Control samples

(% Recovery)

Matrix Spike Recovery Range (%)

LCS Fairfield Little MiamiPFBA 20 213169 96 83-97 17-166PFPeA 20 263219 91 82-98 85-101PFHxA 2 313269 93 74-96 67-98

2 313119 91 76-94 62-87PFHpA 2 363319 94 71-100 62-98

2 363169 95 70-100 65-97PFOA 2 413369 96 78-108 58-100

2 413169 97 78-107 53-102PFNA 2 463419 100 80-106 33-100

2 463219 99 80-104 34-100PFDA 2 513469 86 53-100 55-91

2 513269 84 53-102 57-922 513219 87 55-96 56-92

PFUnA 2 563519 100 84-112 52-1102 563319 101 84-115 49-1062 563 269 100 84-110 51-110

PFDoA 2 613569 101 70-118 79-1082 613369 104 67-114 92-1022 613169 99 67-124 80-113

PFTriA 10 663619 100 89-106 66-10610 663419 105 90-111 65-10610 663169 103 91-106 66-108

PFTreA 10 713669 97 79 -100 65-10710 713469 101 86-100 62-11010 713169 94 82-96 65-103

PFBS 2 29999 74 72-81 65-812 29980 77 67-81 72-82

PFHxS 2 39999 86 74-99 74-912 39980 88 75-102 80-96

PFOS 2 49999 95 44-127 54-972 49980 92 56-122 57-101

PFechS 2 461381 90 91-96 85-972 46199 90 91-94 83-96

Method Blanks Lower than Reporting Limits

Native Unspiked Concentrations

ChemicalMatrix spike

(ng/L)

UnspikedInfluent (ng/L)

UnspikedEffluent with Supplement

(ng/L)

UnspikedEffluent without

Supplement (ng/L)

Native One Native Two Native ThreePFBA 400 4.4 6146 6812PFPeA 400 19.2 45.8 50PFHxA 80 16.6 24.8 42PFHpA 80 4.8 8.6 9.6PFOA 80 19.6 94.2 72.2PFNA 80 8 55.6 28.8PFDA 80 42.6 304.2 147PFUnA 80 25.2 80.2 40.2PFDoA 80 67 247.8 117.2PFTriA 400 34.2 100.6 44.6PFTreA 400 53 198.4 104.8PFBS 80 3.6 16.4 24.4PFHxS 80 12.4 12 7PFOS 80 151.4 583.8 285.8PFechS 80 2 2.6 1.8*

Soil Matrix Samples

• Earthgro potting soil• Miracle‐Gro moisture control garden soil• Vigoro organic garden soil• Miracle‐Gro organic choice• Scotts premium top soil• Milorganite

Example Soil Matrix

CompoundMatrix Spike

(ng/Kg)

UnspikedNative Soil

(ng/Kg)

Average Matrix Spike %

RecoveryPFTReA 1000 50 12PFTRiA 1000 48 41PFDoA 200 89 75PFuNA 200 66 90PFDA 200 110 70PFOS 200 772 119PFNA 200 129 98

PFechS 200 9 94PFOA 200 397 104PFHxS 200 83 101PFHpA 200 168 94PFHxA 200 360 102PFBS 200 350 93PFPeA 1000 429 77PFBA 1000 724 63

Method Blanks Lower than Reporting Limits‐ In the sand, not in solvent blanks! PFOA‐ 11 ng/Kg and PFOA‐ 16 ng/Kg (RL 25 ng/Kg)

Spike Insignificant for Some Samples

Compound Transition

Matrix Spike

(ng/Kg)

Conentration in 2 g sample (ng/kg wet weight)

Soil1 Soil1Dup Soil1 MS Soil1 MSD

PFuNA 563519 200 22950 23400 21900 23775

563319 200 22425 23150 19800 22725

PFDA 513269 200 11975 12250 11000 11725

513219 200 13475 11800 12750 11750

PFOS 49999 200 1075 1025 1075 1325

49980 200 1050 1275 950 1200

PFNA 463419 200 975 1150 1125 1250

463219 200 1400 1500 1325 1500

PFOA 413369 200 1375 1825 1275 1625

413169 200 1375 1300 1250 1400

PFHxA 313269 200 22950 23400 21900 23775

313119 200 22425 23150 19800 22725

FTOHs in Sludge

Chemical

Matrix Spike (µg/L)

Percent Recovery

Laboratory Control Matrix Spike

(5 ml Water) (5 ml Sludge)

LCS1 LCS2 Average SludgeMS1 SludgeMS2 Average

10:2 FTOH 563523 10 102 112 107 67 68 68

10:2 FTOH 563503 10 102 108 105 68 70 69

10:2 FTOH 563455 10 102 107 105 71 71 71

8:2 FTOH 463423 10 67 71 69 46 51 48

8:2 FTOH 463403 10 73 76 75 51 50 51

8:2 FTOH 463355 10 72 76 74 52 52 52

7:2s FTOH 393333 10 68 69 69 64 62 63

7:2s FTOH 393219 10 67 70 69 61 59 60

6:2 FTOH 363323 20 46 62 54 12 6 9

6:2 FTOH 363303 20 56 59 57 16 20 18

4:2 FTOH 263223 200 76 76 76 42 35 38

4:2 FTOH 263203 200 63 71 67 43 40 42

4:2 FTOH 263155 200 81 86 83 60 56 58

FTOHs in Biosolids

Chemical

Matrix spike

(µg/kg)

Percentage Recovery (%)

Laboratory Control Matrix Spike

(2g Ottawa Sand) (~ 2 g Biosolid)

LCS1 LCS2 Average MS1 MS2 Average

10:2 FTOH 563523 25 114 114 114 26 23 24

10:2 FTOH 563503 25 110 115 112 27 24 25

10:2 FTOH 563455 25 110 109 109 27 24 25

8:2 FTOH 463423 25 86 79 82 5 8 7

8:2 FTOH 463403 25 83 86 85 16 13 15

8:2 FTOH 463355 25 90 91 90 15 17 16

7:2s FTOH 393333 25 95 102 98 49 49 49

7:2s FTOH 393219 25 97 99 98 46 47 47

6:2 FTOH 363323 50 77 78 78 NR NR NR

6:2 FTOH 363303 50 77 78 77 NR NR NR

4:2 FTOH 263223 500 77 78 77 NR NR NR

4:2 FTOH 263203 500 79 76 78 NR NR NR

4:2 FTOH 263155 500 83 86 85 NR NR NR

Conclusion/Discussion• Quick, pretty robust analysis• Not Regulatory!!!• Working on Finalizing Method using many matrices.

• Do you have any suggestions or background in these analyses to help me out!

Quick and Effective Extraction of Perfluorinated in water ... · Chicago Regional Laboratory, nor...

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