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Incorporating Ultrashort-Chain Compounds into Comprehensive PFAS Analysis in Waters

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Abstract

A simple and reliable workflow was established here for analyzing 45 PFAS compounds in both potable and non-potable waters. The target analytes included C2 to C14 perfluoroalkyl carboxylic acids (PFCA); C1 to C13 perfluoroalkyl sulfonic acids (PFSA); fluorotelomer carboxylic acids and sulfonic acids; perfluorooctane sulfonamides and sulfonamidoacetic acids; and per- and polyfluoroether carboxylic acids and sulfonic acids. Method suitability was evaluated in terms of linearity, accuracy, precision, and suitability for a range of water types. The method produced exceptional chromatographic performance, providing a tool for comprehensive PFAS analysis that overcomes the challenges associated with conventional reversed-phase liquid chromatography (RPLC).

Introduction

Ultrashort-chain per- and polyfluoroalkyl substances (PFAS) are small, very polar compounds with carbon chain lengths shorter than C4 (Figure 1). Their ubiquitous presence and high levels in environmental aquatic systems are emerging as a significant concern, rivaling the well-established issues associated with long-chain PFAS contamination. Therefore, it is important to analyze both ultrashort-chain and longer chain PFAS together in water samples to comprehensively assess the full spectrum of PFAS contamination. Methods allowing concurrent analysis of C1-C14 PFAS will be important tools in PFAS testing because they will allow a better understanding of environmental fate and potential human exposure, which is critical to developing effective regulations and remediation strategies.

The development of comprehensive PFAS methods that include ultrashort-chain compounds is challenging because the high polarity of ultrashort-chain PFAS makes it difficult to obtain adequate retention with an RPLC method and C18 column, which is the typical approach for analyzing C4 and longer PFAS in water. Obtaining adequate retention and separation from matrix interferences is particularly problematic for early eluting compounds, such as TFA. GC-MS has been used for analyzing TFA and C4-C6 PFCA in water samples, but it requires an extra step for PFCA derivatization and does not allow simultaneous analysis of PFSA [1]. Ultrashort-chain PFAS have also been analyzed using anion-exchange LC, but method run times exceed 20 minutes and broad peaks were observed [2]. We have previously developed a rapid method for the analysis of ultrashort- and short-chain PFAS in water samples using a hybrid HILIC and ion-exchange LC column [3], but it did not incorporate long-chain PFAS. More recently, we developed a method to quantify C1 to C10 PFAS in human plasma and serum utilizing a polar-embedded alkyl phase LC column [4]. Based on the effectiveness of that method, we used it as a starting point for the current study, which aims to develop a new method for testing a broader range of PFAS in water matrices.

The method developed here uses an LC column with a polar-embedded alkyl stationary phase to ensure adequate retention of early eluting polar compounds. In addition, the column is made with hardware treated with an inert coating, which improves sensitivity by preventing any unwanted analyte interactions with the stainless-steel column. Using this Ultra Inert IBD column, a simple and reliable workflow was developed for the simultaneous analysis of C1 to C14 perfluoroalkyl carboxylic and sulfonic acids along with other groups of PFAS. Method performance was assessed for linearity, accuracy, precision, and suitability across a wide range of potable and non-potable water matrices.

Figure 1: Structures of C1 to C3 PFAS

chemical structures of trifluoromethanesulfonic acid (TFMS), trifluoroacetic acid (TFA), perfluoroethane sulfonate (PFEtS), perfluoropropionic acid (PFPrA), and perfluoropropane sulconate (PFPrS)

Experimental

Water Samples

Wastewater samples were gifts from General Dynamics Information Technology (Falls Church, VA). These included effluents from a publicly owned treatment works (POTW); a hospital; a metal finisher; and a chemical manufacturer. Bottled waters were obtained from local grocery stores. Tap waters were collected from Restek Corporation (Bellefonte, PA) and local households served by different borough water authorities. In addition, a natural spring water, two well waters, and three creek waters were collected from regions in central Pennsylvania.

Standard and Sample Preparation

The working calibration standard solutions (250 µL each) were prepared in reverse osmosis water across a range of 1 to 1000 ng/L in polypropylene HPLC vials. Five mass-labeled PFAS were used as quantitative internal standards (QIS) (Table I). A 2 µL aliquot of QIS working solution containing 40 ng/mL of 13C3-PFBA; 20 ng/mL of 13C2-PFHxA and 13C4-PFOA; and 10 ng/mL of 13C5-PFNA and 1313C2-PFDA was added to each standard solution, followed by mixing with 250 µL of methanol containing 1% acetic acid.

Tap water, bottled spring water, and treated sewage wastewater effluent from a POTW facility were used for the assessment of method accuracy and precision. Tap water and bottled water were used directly without filtration. The POTW water (~10 mL) was filtered with polypropylene syringe filters (cat.# 28936) and collected in 50-mL polypropylene tubes (cat.# 25846). These water samples (250 µL) were fortified at concentrations of 2, 4, 10, 50, and 250 ppt with native analytes and isotopically labeled 13C-TFA, which served as a surrogate for the determination of TFA recovery. Each fortified sample was mixed with 2 µL of QIS working solution and 2.5 µL of extracted internal standards (EIS) working solution containing 10 ng/mL of mass-labeled PFAS as detailed in Table I. A 250 µL aliquot of methanol containing 1% acetic acid was then added and mixed with the fortified samples for LC-MS/MS analysis.

Analytical System

Analysis of C1-C14 PFAS in the water samples was performed by LC-MS/MS under the conditions shown below. A PFAS delay column was installed between the mixer and injector to prevent any potential PFAS contamination upstream of the injector from coeluting with PFAS in the samples. The MS/MS transition parameters for each analyte are provided in Table I.

System: Waters ACQUITY UPLC and Xevo TQ-S triple quadrupole mass spectrometer
Columns:
  • Analytical column: Ultra Inert IBD, 100 mm x 2.1 mm, 3 µm (cat.# 9175312-T)
  • PFAS delay column (cat.# 27854)
Injection volume: 45 µL
Mobile phase A: 5 mM ammonium formate, 0.1% formic acid in water
Mobile phase B: Acetonitrile
Flow rate: 0.4 mL/min
Temperature: 40 °C
Gradient:  

Time (min)

0.00

7.00

10.00

10.01

12.00

%B

50

95

95

50

50

Ion mode: Negative ESI
Mode: Scheduled MRM

 

Table I: MS Transitions and Analyte Retention Times

Compounds Time (min) Precursor Ion

Product Ions*

Cone (V) Collision (V) Internal Standard
Target Analytes
Perfluoroalkyl carboxylic acids
Trifluoroacetic acid (TFA) 2.12 113.03 [M-H]- 69.01 10 10 13C3-PFBA
Perfluoropropanoic acid (PFPrA) 2.69 162.97 [M-H]- 119.02 10 8 13C3-PFBA
Perfluorobutanoic acid (PFBA) 3.27 213.03 [M-H]- 168.98 14 8 13C3-PFBA
Perfluoropentanoic acid (PFPeA) 3.94 262.97 [M-H]- 218.97 2 6 13C2-PFHxA
Perfluorohexanoic acid (PFHxA) 4.59 313.10 [M-H]- 268.97/118.99 2 8/20 13C2-PFHxA
Perfluoroheptanoic acid (PFHpA) 5.24 363.16 [M-H]- 319.09/169.06 8 10/18 13C4-PFOA
Perfluorooctanoic acid (PFOA) 5.86 413.10 [M-H]- 368.96/168.90 2 10/16 13C4-PFOA
Perfluorononanoic acid (PFNA) 6.45 463.10 [M-H]- 419.01/219.02 4 10/16 13C5-PFNA
Perfluorodecanoic acid (PFDA) 7.03 513.17 [M-H]- 469.16/219.06 4 12/16 13C2-PFDA
Perfluoroundecanoic acid (PFUnA) 7.60 563.23 [M-H]- 519.24/269.07 6 12/18 13C2-PFDA
Perfluorododecanoic acid (PFDoA) 8.23 613.23 [M-H]- 569.19/169.06 8 12/26 13C2-PFDA
Perfluorotridecanoic acid (PFTrDA) 8.99 663.23 [M-H]- 619.21/169.06 8 14/28 13C2-PFDA
Perfluorotetradecanoic acid (PFTeDA) 9.83 712.67 [M-H]- 668.69/168.94 10 12/26 13C2-PFDA
Perfluoroalkyl sulfonic acids
Trifluoromethanesulfonic acid (TFMS) 2.36 148.97 [M-H]- 79.93/98.92 62 18/18 13C3-PFBA
Perfluoroethanesulfonic acid (PFEtS) 2.89 198.90 [M-H]- 79.92/98.91 38 22/22 13C3-PFBA
Perfluoropropanesulfonic acid (PFPrS) 3.44 248.97 [M-H]- 79.92/98.91 2 24/24 13C3-PFBA
Perfluorobutanesulfonic acid (PFBS) 3.97 298.97 [M-H]- 79.97/98.89 2 26/26 13C2-PFHxA
Perfluoropentanesulfonic acid (PFPeS) 4.50 349.10 [M-H]- 79.98/98.98 6 32/30 13C2-PFHxA
Perfluorohexanesulfonic acid (PFHxS) 5.01 398.90 [M-H]- 79.97/98.89 56 32/34 13C2-PFHxA
Perfluoroheptanesulfonic acid (PFHpS) 5.50 449.17 [M-H]- 79.98/98.97 4 42/38 13C4-PFOA
Perfluorooctanesulfonic acid (PFOS) 5.96 499.03 [M-H]- 79.92/98.90 8 40/40 13C4-PFOA
Perfluorononanesulfonic acid (PFNS) 6.38 549.10 [M-H]- 79.92/98.83 12 42/40 13C5-PFNA
Perfluorodecanesulfonic acid (PFDS) 6.77 599.17 [M-H]- 79.98/98.83 8 44/46 13C2-PFDA
Perfluoroundecanesulfonic acid (PFUdS) 7.12 648.73 [M-H]- 79.94/98.94 38 50/44 13C2-PFDA
Perfluorododecanesulfonic acid (PFDoS) 7.44 698.77 [M-H]- 79.95/98.94 10 60/44 13C2-PFDA
Perfluorotridecanesulfonic acid (PFTrDS) 7.73 748.73 [M-H]- 79.94/98.94 8 76/52 13C2-PFDA
Fluorotelomer sulfonic acids
1H,1H,2H,2H-Perfluorohexane sulfonic acid (4:2 FTS) 4.22 327.10 [M-H]- 307.08/80.83 50 18/24 13C2-PFHxA
1H,1H,2H,2H-Perfluorooctane sulfonic acid (6:2 FTS) 5.75 427.17 [M-H]- 407.18/80.71 2 22/32 13C4-PFOA
1H,1H,2H,2H-Perfluorodecane sulfonic acid (8:2 FTS) 7.22 527.17 [M-H]- 507.16/80.83 66 26/32 13C2-PFDA
Fluorotelomer carboxylic acids
3-Perfluoropropyl propanoic acid (3:3 FTCA) 1.64 241.00 [M-H]- 177.00/117.00 2 6/6 13C3-PFBA
3-Perfluoropentyl propanoic acid (5:3 FTCA) 2.49 340.93 [M-H]- 216.96/236.93 2 24/14 13C3-PFBA
3-Perfluoroheptyl propanoic acid (7:3 FTCA) 3.61 440.90 [M-H]- 336.88/316.91 20 12/22 13C3-PFBA
Perfluorooctane sulfonamides
Perfluorooctanesulfonamide (FOSA) 3.36 498.17 [M-H]- 77.97/477.76 8 28/26 13C3-PFBA
N-methyl perfluorooctanesulfonamide (NMeFOSA) 3.96 511.77 [M-H]- 168.95/218.91 2 26/24 13C2-PFHxA
N-ethyl perfluorooctanesulfonamide (NEtFOSA) 4.26 525.83 [M-H]- 168.96/218.92 10 26/24 13C2-PFHxA
Perfluorooctane sulfonamidoacetic acids
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) 6.44 570.20 [M-H]- 419.17/483.16 46 20/14 13C5-PFNA
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) 6.56 584.20 [M-H]- 419.18/483.11 6 20/16 13C5-PFNA
Per- and polyfluoroether carboxylic acids
Perfluoro-3-methoxypropanoic acid (PFMPA) 3.40 228.93 [M-H]- 84.97/198.94 10 10/14 13C3-PFBA
Perfluoro-4-methoxybutanoic acid (PFMBA) 4.00 278.87 [M-H]- 84.96/234.93 8 10/6 13C2-PFHxA
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) 4.06 294.93 [M-H]- 200.91/85.02 8 4/22 13C2-PFHxA
Hexafluoropropylene oxide dimer acid (HFPO-DA) 4.46 285.03 [M-COOH]- 169.02/185.02 2 6/16 13C2-PFHxA
4,8-Dioxa-3H-perfluorononanoic acid (ADONA) 4.63 376.90 [M-H]- 250.93/84.97 22 12/26 13C2-PFHxA
Ether sulfonic acids
Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA) 4.04 314.83 [M-H]- 134.94/83.01 4 22/16 13C2-PFHxA
9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS) 5.88 530.78 [M-H]- 350.85/82.96 12 26/24 13C4-PFOA
11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) 6.56 630.78 [M-H]- 450.80/82.95 8 26/32 13C5-PFNA
Extracted Internal Standards
13C3-PFPrA 2.69 165.97 [M-H]- 120.96 10 11 13C3-PFBA
13C4-PFBA 3.27 217.03 [M-H]- 171.98 2 8 13C3-PFBA
13C5-PFPeA 3.94 267.97 [M-H]- 222.99 2 6 13C2-PFHxA
13C5-PFHxA 4.59 318.03 [M-H]- 272.93 2 7 13C2-PFHxA
13C4-PFHpA 5.24 366.90 [M-H]- 321.93 2 10 13C4-PFOA
13C8-PFOA 5.86 420.97 [M-H]- 375.94 2 10 13C4-PFOA
13C6-PFDA 7.03 518.90 [M-H]- 473.87 4 13 13C2-PFDA
13C7-PFUnA 7.60 569.90 [M-H]- 524.87 2 12 13C2-PFDA
13C2-PFDoA 8.23 614.84 [M-H]- 569.87 2 12 13C2-PFDA
13C2-PFTeDA 9.83 714.78 [M-H]- 669.80 8 14 13C2-PFDA
13C3-PFBS 3.97 301.97 [M-H]- 79.97 2 28 13C2-PFHxA
13C3-PFHxS 5.01 401.90 [M-H]- 79.97 2 36 13C2-PFHxA
13C8-PFOS 5.96 506.84 [M-H]- 79.97 4 42 13C4-PFOA
13C2-4:2 FTS 4.22 328.97 [M-H]- 308.96 2 18 13C2-PFHxA
13C2-8:2 FTS 7.22 528.90 [M-H]- 508.90 2 24 13C2-PFDA
13C8-FOSA 3.36 505.91 [M-H]- 77.95 4 32 13C3-PFBA
d3-NMeFOSAA 6.44 572.90 [M-H]- 418.91 50 18 13C5-PFNA
d5-NEtFOSAA 6.56 588.97 [M-H]- 418.86 48 20 13C5-PFNA
Quantification Internal Standards
13C3-PFBA 3.27 215.97 [M-H]- 171.97 10 8 -
13C2-PFHxA 4.59 314.97 [M-H]- 269.93 8 8 -
13C4-PFOA 5.86 416.87 [M-H]- 371.88 2 8 -
13C5-PFNA 6.45 467.87 [M-H]- 422.89 16 10 -
13C2-PFDA 7.03 514.87 [M-H]- 469.84 8 10 -

*Quantifier ion/qualifier ion.

Results and Discussion

LC-MS/MS Method Development

An effective chromatographic method was established for the comprehensive analysis of 45 PFAS, including ultrashort-chain compounds, in potable and non-potable water samples (Figure 2). The Ultra Inert IBD column exhibited excellent chromatographic performance under reversed-phased conditions, with the embedded polar group providing good retention of TFA and other early eluting PFAS. In addition, as shown in Figure 3, the inert hardware resulted in a notable enhancement in detection sensitivity for most of the analytes (3-70% increase in peak area and 5-75% increase in peak height) compared to columns with uncoated hardware.

Figure 2: Analysis of a 500 ppt PFAS Standard

cgarm-img
LC_EV0597

 

Figure 3: Inert LC column hardware increased peak area and height for most PFAS compared to columns made with traditional stainless-steel hardware.

bar charts for peak area and height

 

Linearity

Employing quadratic regression (1/x weighted), all analytes exhibited acceptable linearities with r2 >0.995 and deviations <30%. Table II shows the different linearity ranges for each target PFAS, which ranged from 1 ppt to 1000 ppt, with variation occurring at the lowest calibration concentration. LOQ and LOD values are also presented (LOQ values were defined as the concentration of the lowest calibration standard for each analyte).

Table II: LOQ* and LOD Values for PFAS in Tap, Bottled, and POTW Water

  Linearity Range LOD (ng/L)
Analytes (ng/L) Tap Water Bottled Water POTW
TFA 10–1000 1.7 1.4 2.1
PFPrA 1–1000 0.3 0.3 0.3
PFBA 2–1000 0.7 0.6 0.6
PFPeA 1–1000 0.5 0.4 0.3
PFHxA 1–1000 0.4 0.4 0.4
PFHpA 1–1000 0.4 0.4 0.5
PFOA 1–1000 0.4 0.4 0.4
PFNA 1–1000 0.3 0.3 0.3
PFDA 1–1000 0.4 0.3 0.5
PFUnA 1–1000 0.5 0.3 0.4
PFDoA 2–1000 0.7 0.4 0.5
PFTrDA 2–1000 0.8 0.6 0.6
PFTeDA 2–1000 0.8 0.7 0.6
TFMS 1–1000 0.2 0.2 0.2
PFEtS 1–1000 0.1 0.3 0.2
PFPrS 1–1000 0.2 0.2 0.4
PFBS 1–1000 0.2 0.2 0.5
PFPeS 1–1000 0.2 0.3 0.2
PFHxS 1–1000 0.3 0.6 0.5
PFHpS 2–1000 0.5 0.4 0.4
PFOS 2–1000 0.5 0.9 0.8
PFNS 2–1000 0.6 0.6 0.6
PFDS 2–1000 0.6 0.7 0.9
PFUdS 2–1000 0.5 0.7 0.9
PFDoS 2–1000 0.4 0.6 0.6
PFTrDS 2–1000 0.9 0.6 0.8
4:2 FTS 2–1000 0.4 0.6 0.5
6:2 FTS 2–1000 0.6 0.4 0.5
8:2 FTS 2–1000 0.4 0.4 0.5
3:3 FTCA 20–1000 8.3 7.4 -
5:3 FTCA 4–1000 1.2 1.1 1.5
7:3 FTCA 4–1000 1.6 1.3 1.2
FOSA 1–1000 0.2 0.2 0.2
NMeFOSA 10–1000 3.8 4.0 4.0
NEtFOSA 10–1000 4.6 4.0 4.0
NMeFOSAA 4–1000 1.2 1.2 1.9
NEtFOSAA 10–1000 4.3 2.5 3.3
PFMPA 1–1000 0.3 0.2 0.4
PFMBA 1–1000 0.4 0.3 0.4
NFDHA 20–1000 10.0 8.8 7.9
HFPO-DA 10–1000 3.8 3.3 5.2
ADONA 1–1000 0.1 0.1 0.2
PFEESA 1–1000 0.1 0.1 0.1
9Cl-PF3ONS 1–1000 0.2 0.2 0.2
11Cl-PF3OUdS 1–1000 0.2 0.1 0.3

*LOQ = concentration of the lowest calibration standard solution.

 

Accuracy and Precision

Three batches of samples were analyzed on different days, totaling nine replicates for each fortification level. The average recoveries and relative standard deviations (RSD) are presented in Tables III-V. All analytes exhibited good recovery values within the range of 70–130% across all fortification levels. Satisfactory method precision was demonstrated by %RSD values of <20%. Additionally, the results indicated that all extracted internal standards (EIS) had recovery values within 30% of the nominal concentration.

Table III: Accuracy and Precision Results for Tap Water Samples

Analytes Average Recovery (RSD, %), n=9
Fortified Concentration (ng/L)
2 4 10 50 250
13C-TFA - - 110 (9.61) 89.8 (5.10) 91.5 (2.04)
PFPrA 102 (6.88) 100 (3.72) 98.6 (6.71) 105 (8.98) 101 (6.85)
PFBA 108 (8.17) 107 (7.28) 104 (9.06) 104 (5.13) 103 (7.20)
PFPeA 109 (9.02) 115 (2.98) 105 (7.90) 111 (6.13) 107 (8.17)
PFHxA 88.2 (8.36) 99.8 (8.44) 92.0 (6.26) 105 (7.96) 103 (8.06)
PFHpA 88.7 (6.44) 101 (8.38) 86.2 (6.26) 95.1 (6.97) 91.2 (7.28)
PFOA 111 (6.58) 117 (4.67) 103 (9.51) 104 (8.34) 101 (8.98)
PFNA 108 (7.53) 110 (5.46) 97.8 (3.83) 104 (6.23) 99.5 (8.40)
PFDA 99.4 (6.34) 104 (5.56) 95.1 (5.35) 98.6 (9.37) 95.8 (8.66)
PFUnA 110 (14.0) 109 (11.4) 108 (14.6) 107 (8.05) 95.5 (7.14)
PFDoA 103 (14.2) 104 (9.98) 96.5 (14.1) 101 (5.81) 102 (3.95)
PFTrDA 101 (13.3) 91.1 (11.0) 87.5 (7.09) 82.3 (5.23) 86.5 (3.05)
PFTeDA 103 (6.04) 91.2 (10.6) 90.1 (8.18) 86.5 (10.9) 93.4 (4.21)
TFMS 112 (9.16) 108 (10.4) 97.3 (8.16) 105 (6.42) 104 (7.25)
PFEtS 103 (8.31) 115 (5.52) 103 (3.25) 106 (4.64) 107 (5.60)
PFPrS 109 (9.22) 114 (7.23) 99.3 (8.52) 106 (7.76) 107 (7.32)
PFBS 109 (6.89) 109 (10.7) 94.3 (8.59) 101 (5.45) 102 (6.53)
PFPeS 104 (5.33) 113 (3.79) 97.9 (4.84) 106 (7.29) 104 (9.30)
PFHxS 84.1 (16.7) 105 (7.50) 90.8 (12.8) 104 (4.37) 102 (3.77)
PFHpS 111 (7.72) 108 (6.82) 99.7 (7.04) 108 (5.65) 105 (6.59)
PFOS 112 (7.55) 106 (7.10) 95.5 (10.2) 107 (7.39) 107 (6.83)
PFNS 117 (13.8) 104 (10.7) 91.9 (10.2) 104 (4.92) 99.1 (6.15)
PFDS 107 (15.0) 106 (8.32) 94.4 (17.2) 97.9 (11.1) 94.4 (3.40)
PFUdS 108 (13.5) 92.4 (15.5) 88.1 (1.58) 85.7 (2.32) 93.4 (3.38)
PFDoS 114 (13.4) 96.5 (11.9) 85.9 (5.01) 83.5 (11.6) 93.9 (2.71)
PFTrDS 91.0 (17.8) 72.5 (18.2) 72.0 (13.8) 72.9 (14.4) 84.6 (3.55)
4:2 FTS 106 (8.72) 109 (8.83) 90.2 (13.0) 103 (9.27) 101 (10.2)
6:2 FTS 108 (8.94) 112 (6.81) 96.4 (17.3) 102 (4.45) 99.4 (7.60)
8:2 FTS 111 (13.4) 107 (12.1) 92.6 (11.3) 101 (5.28) 94.6 (5.86)
3:3 FTCA - - - 83.7 (8.92) 82.6 (5.64)
5:3 FTCA - 120 (6.07) 106 (12.0) 103 (8.99) 103 (8.78)
7:3 FTCA - 107 (8.36) 91.4 (16.2) 105 (7.98) 106 (7.36)
FOSA 107 (9.41) 107 (5.20) 95.4 (8.59) 95.7 (4.63) 95.5 (6.05)
NMeFOSA - - 106 (12.9) 105 (6.50) 104 (9.06)
NEtFOSA - - 105 (14.7) 112 (4.89) 105 (7.49)
NMeFOSAA - 123 (7.06) 88.5 (14.6) 102 (8.37) 99.5 (7.89)
NEtFOSAA - - 106 (10.9) 96.1 (11.1) 92.6 (5.99)
PFMPA 99.0 (15.9) 103 (10.6) 90.2 (6.11) 103 (8.22) 103 (8.21)
PFMBA 105 (7.67) 107 (8.82) 95.8 (7.63) 107 (6.27) 103 (7.01)
NFDHA - - - 115 (9.78) 115 (8.61)
HFPO-DA - - 115 (13.1) 108 (5.70) 106 (7.76)
ADONA 94.4 (11.5) 109 (5.71) 98.4 (7.58) 106 (7.56) 104 (8.94)
PFEESA 102 (8.88) 113 (4.75) 98.8 (7.11) 108 (6.06) 105 (8.76)
9Cl-PF3ONS 100 (8.99) 107 (4.54) 95.7 (2.88) 105 (6.31) 104 (9.09)
11Cl-PF3OUdS 88.2 (12.3) 96.8 (7.36) 87.8 (8.81) 96.7 (4.65) 95.1 (4.17)

 

Table IV: Accuracy and Precision Results for Bottled Water Samples

Analytes Average Recovery (RSD, %), n=9
Fortified Concentration (ng/L)
2 4 10 50 250
13C-TFA - - 104 (15.6) 99.4 (8.09) 103 (7.45)
PFPrA 96.7 (5.90) 101 (6.64) 97.9 (6.08) 107 (3.13) 114 (7.77)
PFBA 96.4 (5.81) 94.7 (8.49) 90.2 (6.21) 103 (6.58) 112 (6.78)
PFPeA 93.2 (8.17) 99.1 (13.9) 95.5 (10.2) 105 (5.95) 111 (8.53)
PFHxA 100 (13.1) 96.5 (9.30) 91.0 (8.66) 99.5 (4.92) 108 (8.20)
PFHpA 96.9 (8.26) 92.3 (3.67) 87.3 (4.82) 97.9 (6.15) 104 (5.56)
PFOA 94.4 (10.9) 100 (10.8) 101 (8.29) 105 (6.09) 112 (6.11)
PFNA 108 (9.34) 103 (8.32) 97.3 (3.99) 105 (5.46) 112 (7.09)
PFDA 101 (11.9) 96.9 (6.73) 92.2 (8.25) 100 (5.31) 109 (8.86)
PFUnA 109 (10.6) 104 (8.74) 90.6 (11.0) 97.7 (9.52) 105 (5.72)
PFDoA 97.5 (5.77) 95.2 (4.93) 78.5 (1.90) 85.1 (5.14) 103 (5.68)
PFTrDA 106 (9.03) 100 (8.97) 81.8 (13.1) 87.8 (18.6) 98.2 (9.05)
PFTeDA 116 (3.97) 109 (6.74) 90.5 (8.94) 93.5 (18.2) 114 (5.74)
TFMS 101 (9.04) 107 (6.85) 96.7 (4.30) 106 (2.88) 112 (7.17)
PFEtS 102 (7.45) 105 (4.66) 97.8 (3.00) 106 (2.01) 111 (7.50)
PFPrS 101 (10.4) 106 (7.28) 98.1 (6.13) 108 (1.98) 111 (6.44)
PFBS 103 (13.7) 101 (9.53) 85.8 (5.98) 101 (2.59) 108 (8.90)
PFPeS 95.6 (10.3) 102 (5.75) 92.3 (5.80) 102 (2.79) 109 (9.05)
PFHxS 110 (8.75) 99.4 (8.55) 90.9 (11.8) 96.5 (2.79) 103 (8.67)
PFHpS 99.8 (8.79) 94.2 (8.80) 90.9 (7.75) 105 (5.47) 110 (8.06)
PFOS 111 (12.9) 93.5 (8.65) 91.8 (9.70) 106 (6.02) 109 (6.08)
PFNS 102 (12.8) 90.8 (15.2) 86.8 (10.4) 101 (8.80) 112 (6.74)
PFDS 96.9 (19.1) 105 (12.1) 89.3 (11.4) 103 (10.2) 107 (5.82)
PFUdS 101 (18.5) 100 (16.3) 87.3 (10.5) 92.9 (14.5) 105 (5.71)
PFDoS 114 (7.52) 106 (10.7) 84.8 (14.6) 90.7 (14.5) 108 (7.49)
PFTrDS 126 (1.13) 109 (14.4) 86.2 (17.1) 88.4 (19.0) 112 (5.51)
4:2 FTS 103 (11.0) 98.1 (16.3) 88.6 (10.1) 94.3 (4.60) 108 (10.3)
6:2 FTS 108 (6.44) 95.2 (13.7) 88.0 (13.3) 97.7 (9.07) 106 (7.53)
8:2 FTS 112 (10.5) 109 (5.14) 95.0 (3.66) 103 (3.89) 109 (8.72)
3:3 FTCA - - - 95.4 (10.4) 105 (6.94)
5:3 FTCA - 103 (8.78) 94.3 (12.1) 105 (6.32) 109 (8.62)
7:3 FTCA - 115 (5.16) 98.9 (9.92) 102 (8.75) 110 (7.09)
FOSA 111 (7.75) 103 (8.73) 91.6 (3.72) 104 (3.88) 112 (7.06)
NMeFOSA - - 105 (8.01) 101 (10.8) 115 (5.88)
NEtFOSA - - 121 (9.43) 100 (13.0) 110 (8.06)
NMeFOSAA - 109 (12.1) 106 (10.1) 92.9 (13.8) 104 (9.53)
NEtFOSAA - - 101 (15.7) 100 (10.3) 105 (8.11)
PFMPA 99.5 (9.11) 99.6 (11.0) 92.2 (4.76) 103 (4.57) 112 (7.29)
PFMBA 92.3 (9.01) 102 (9.17) 90.1 (8.50) 100 (4.51) 109 (7.70)
NFDHA - - - 111 (6.59) 111 (7.73)
HFPO-DA - - 106 (12.3) 101 (10.1) 112 (6.19)
ADONA 97.3 (11.4) 101 (6.41) 91.6 (3.35) 100 (4.26) 107 (10.3)
PFEESA 101 (8.99) 105 (8.33) 93.6 (5.67) 102 (3.03) 110 (9.16)
9Cl-PF3ONS 100 (8.53) 101 (7.16) 90.2 (4.28) 105 (4.22) 112 (8.47)
11Cl-PF3OUdS 91.0 (11.1) 96.8 (6.21) 85.0 (4.94) 100 (11.8) 108 (5.75)

 

Table V: Accuracy and Precision Results for POTW Water Samples

Analytes Average Recovery (RSD, %), n=9
Fortified Concentration (ng/L)
2 4 10 50 250
13C-TFA - - - 104 (9.46) 108 (8.57)
PFPrA 99.7 (3.96) 101 (11.9) 99.7 (9.18) 109 (3.90) 113 (1.99)
PFBA 100 (8.79) 98.0 (6.35) 99.2 (7.44) 104 (8.77) 106 (4.82)
PFPeA 104 (9.17) 110 (6.19) 101 (5.66) 109 (2.80) 116 (2.05)
PFHxA 91.8 (12.1) 98.5 (10.0) 92.9 (9.53) 101(3.30) 103 (6.53)
PFHpA 115 (5.90) 111 (8.16) 97.6 (6.90) 97.1 (5.74) 99.5 (4.58)
PFOA 108 (8.67) 105 (8.15) 101 (4.86) 105 (4.68) 109 (5.20)
PFNA 113 (8.50) 117 (5.50) 95.1 (5.73) 103 (6.97) 107 (4.67)
PFDA 108 (10.6) 111 (8.44) 91.8 (5.90) 97.6 (4.10) 101 (3.49)
PFUnA 106 (12.6) 102 (9.97) 95.1 (8.99) 97.7 (3.90) 101 (6.28)
PFDoA 98.4 (16.6) 107 (9.05) 93.0 (3.83) 111 (11.9) 112 (12.2)
PFTrDA 94.1 (15.9) 94.4 (13.2) 79.7 (9.70) 90.3 (11.3) 96.7 (13.5)
PFTeDA 113 (12.7) 97.5 (18.9) 82.9 (12.4) 95.2 (13.3) 104 (18.0)
TFMS 104 (15.6) 108 (7.24) 94.9 (5.45) 94.9 (5.32) 96.0 (1.88)
PFEtS 93.1 (15.3) 108 (7.71) 87.9 (6.50) 95.7 (4.51) 97.9 (2.89)
PFPrS 105 (9.36) 114 (4.26) 91.5 (4.65) 99.5 (3.97) 102 (4.11)
PFBS 93.4 (12.3) 107 (6.18) 91.8 (7.88) 100 (5.38) 105 (6.90)
PFPeS 102 (13.3) 113 (8.62) 90.2 (4.13) 99.7 (2.68) 103 (4.89)
PFHxS 89.3 (17.7) 95.2 (8.96) 100 (12.7) 98.6 (6.64) 105 (6.83)
PFHpS 85.1 (16.1) 109 (9.59) 96.0 (7.89) 106 (3.56) 111 (2.42)
PFOS 79.0 (18.5) 107 (6.22) 86.1 (8.60) 101 (7.45) 110 (4.62)
PFNS 104 (9.28) 92.5 (14.2) 85.0 (9.21) 98.9 (4.69) 108 (3.95)
PFDS 109 (11.1) 106 (11.0) 92.6 (13.1) 101 (7.80) 101 (4.53)
PFUdS 95.6 (18.8) 102 (8.93) 77.9 (7.72) 90.2 (8.96) 96.4 (7.42)
PFDoS 111 (9.06) 95.0 (10.7) 80.0 (13.7) 83.1 (8.45) 99.5 (12.4)
PFTrDS 94.1 (14.9) 107 (15.1) 79.8 (12.5) 85.2 (12.4) 96.4 (15.1)
4:2 FTS 122 (5.65) 113 (4.55) 91.5 (7.23) 100 (3.92) 104 (5.01)
6:2 FTS 110 (10.3) 109 (12.0) 93.1 (10.0) 95.2 (7.65) 102 (5.42)
8:2 FTS 116 (10.0) 102 (16.1) 89.3 (12.6) 101 (5.81) 106 (3.58)
3:3 FTCA - - - - -
5:3 FTCA - 115 (7.21) 104 (8.42) 108 (7.38) 108 (5.05)
7:3 FTCA - 122 (6.51) 92.6 (18.9) 99.7 (9.76) 105 (5.88)
FOSA 110 (8.60) 101 (10.9) 79.1 (4.69) 89.4 (5.01) 96.6 (6.21)
NMeFOSA - - 110 (18.8) 92.1 (10.3) 116 (3.63)
NEtFOSA - - 116 (9.55) 103 (11.9) 104 (11.6)
NMeFOSAA - 118 (10.3) 98.2 (12.1) 98.8 (9.01) 100 (6.96)
NEtFOSAA - - 106 (10.9) 96.1 (11.1) 92.6 (5.99)
PFMPA 94.3 (11.0) 105 (7.54) 88.4 (7.38) 98.1 (3.33) 102 (4.66)
PFMBA 85.9 (7.17) 99.9 (10.5) 87.0 (8.69) 101 (4.18) 109 (5.75)
NFDHA - - - 90.5 (13.9) 114 (3.75)
HFPO-DA - - 111 (6.49) 92.5 (16.2) 95.6 (12.4)
ADONA 90.8 (12.6) 116 (5.19) 90.9 (4.78) 103 (3.45) 106 (5.37)
PFEESA 89.4 (12.7) 113 (8.74) 92.8 (1.95) 102 (1.80) 108 (3.07)
9Cl-PF3ONS 95.4 (10.3) 102 (9.40) 85.4 (6.64) 101 (4.97) 106 (4.67)
11Cl-PF3OUdS 95.1 (8.68) 105 (3.84) 82.7 (4.07) 97.5 (7.82) 101 (6.36)

 

Measurement of 45 Targeted PFAS in Potable and Non-Potable Waters

Each sample was prepared in triplicate with the addition of EIS. Consistent with the accuracy and precision analysis, the recoveries of EIS were within 30% of the nominal concentration (100 ppt) across all source waters. This demonstrated that the established method was suitable for accurate measurement of targeted PFAS, including ultrashort-chain PFAS, in a wide range of water matrices (Table VI).

Table VI: Measurement of 45 Targeted PFAS in Various Water Matrices (nd = non-detected)

Water Samples Averaged Concentration (ng/L)
Ultrashort-Chain Short-Chain
TFA PFPrA TFMS PFBA PFBS PFPeA PFHxA PFHxS PFHpA
Potable Waters
Tap Water #1 176 2.66 8.40 nd nd <1.00 2.13 nd nd
Tap Water #2 317 1.54 7.14 nd 2.25 nd nd nd nd
Tap Water #3 166 3.15 10.9 nd 2.14 2.51 1.24 nd nd
Tap Water #4 330 5.48 12.8 nd 1.68 1.97 nd nd nd
Tap Water #5 1186 29.0 25.4 13.2 8.58 13.7 17.7 nd 5.78
Bottled Water #1 (spring water) 107 nd nd nd nd nd nd nd nd
Bottled Water #2 (spring water) 257 1.66 <1.00 <2.00 1.21 nd nd nd nd
Bottled Water #3 (RO purified) nd nd nd nd nd nd nd nd nd
Natural Spring Water 486 2.91 4.81 nd nd nd nd nd nd
Well Water #1 557 1.82 1.74 nd nd nd nd nd nd
Well Water #2 171 1.16 <1.00 nd nd nd nd nd nd
Non-Potable Waters
Creek Water #1 605 4.88 6.75 5.82 19.5 3.50 1.52 nd <1.00
Creek Water #2 626 3.07 2.26 nd 2.68 nd nd nd nd
Creek Water #3 627 10.9 8.28 <2.00 2.19 4.94 2.35 nd nd
POTW Water Effluent 1156 24.2 9.66 nd 2.84 6.50 24.0 2.28 <1.00
Hospital Effluent 487 3.08 1.45 nd nd 2.15 1.50 nd nd
Metal Finisher Effluent 678 2.78 8.89 2.87 3.11 2.52 2.09 nd nd
Chemical Manufacture Effluent 90,473 8,540 13.3 62.8 1.13 100 7.22 nd 12.0

 

Water Samples  Averaged Concentration (ng/L)
Long-Chain Alternatives
PFOA PFOS PFMPA HFPO-DA
Potable Waters
Tap Water #1 <1.00 nd nd nd
Tap Water #2 nd <2.00 nd nd
Tap Water #3 <1.00 4.76 nd nd
Tap Water #4 nd nd nd nd
Tap Water #5 18.0 5.63 nd nd
Bottled Water #1 (spring water) nd nd nd nd
Bottled Water #2 (spring water) nd <2.00 nd nd
Bottled Water #3 (RO purified) nd nd nd nd
Natural Spring Water nd nd nd nd
Well Water #1 <1.00 nd nd nd
Well Water #2 nd nd nd nd
Non-Potable Waters
Creek Water #1 <1.00 6.06 4.40 nd
Creek Water #2 nd <2.00 nd nd
Creek Water #3 3.08 5.97 nd nd
POTW Water Effluent 12.9 3.88 nd nd
Hospital Effluent nd nd nd nd
Metal Finisher Effluent <1.00 112 nd nd
Chemical Manufacture Effluent 20.8 nd 14.0 5,709

 

Conclusions

A simple and reliable dilute-and-shoot workflow was established in this study to provide a unique solution that incorporates ultrashort-chain PFAS into a comprehensive analysis of PFAS in various water matrices. Use of an Ultra Inert IBD column, which is a polar-embedded alkyl phase column with an inert coating on the hardware, ensured that the method was sensitive, accurate, and precise. Most important, this method can serve as a valuable tool for monitoring these emergent PFAS in environmental water systems and assist in generating guidelines for future regulatory actions. Visit www.restek.com/PFAS for additional products, methods, and technical resources supporting PFAS analysis.

References

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