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Analytical Methodologies for Per/Poly Fluoroalkyl Substances (PFAS) Measurement in Environmental Waters by LC/MS/MS
Tarun Anumol, Ph.D.Applications Development ScientistAgilent Technologies Inc.Wilmington, DE, USA
Contact: [email protected]
Agilent ASTS-Houston
‘Fit for Purpose’ Analysis
8 August 20172
Considerations when selecting analytical technique to employ
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I. Types of analytesII. Concentrations required (ppm,
ppb, ppt etc.)III. Type of matrix (drinking water,
surface water, wastewater, sludge, food etc.)
IV. Type of sample clean-up required V. Regulatory considerations (EPA
methods, EU & ASTM methods etc.)
Factors in deciding analytical method selection
Terminology
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• Terminology of these compounds can be confusing but it is critical to understand the differences
TerminologyFluorinated Compounds
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Any organic or inorganic compound that has a fluorine atom incorporated in it
TerminologyPer/PolyfluoroAlkyl Substances (PFAS)
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R: Continuation of alkyl chain or functional group
When one or more Carbons (C) in an alkyl chain have the Hydrogen (H) replaced by Fluorine (F)
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Terminology
Polyfluoroalkyl substance
ALL H atoms linked to C in alkyl chain are substituted with F
SOME (but not all) H atoms linked to C in alkyl chain are substituted with F
Perfluoroalkyl substance
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TerminologyPerfluoroalkyl acids (PFAAs)
• Perfluorocarboxylic acids (PFCAs)
• Perfluorosulfonic acids (PFSAs)
TerminologyPolyfluorinated compounds - Fluorotelomers
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6:2 FTUCA
8:2 FTUCA
6-C alkyl chain: Hydrophobic 2-C: Hydrophilic
• Formed during the telomerization process in manufacturing
Per/Polyfluoroalkyl substancesUnique Properties
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• Thermal & Chemical stability: grease-proof food packaging, stain repellents
• Zwitterionic properties: surfactants • Surface-tension lowering: fire-fighting foams
Per/Polyfluoroalkyl substancesToxicology & Regulations in US
8 August 201711
Toxicological data:
• PFAS exposure can have adverse effects to the neurological and reproductive systems
• Long chain (>7-C chain) PFASs are bio accumulative, and persistent• Long half-lives for longer chain PFAS• Very difficult to degrade the final products (PFCAs, PFSAs) in the environment
Regulatory Overview:
• USEPA has a public health guidance for PFOA and PFOS at 70 ng/L in drinking water• Many states have their own health guidelines ranging from 20-400 ng/L for PFOS,
PFOA, PFNA and PFHxA
Agilent ASTS-Houston
PFAS Analysis – LC Instrument SetupEliminate Background Contamination
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Application Note: Recommended Plumbing Configurations for Reduction in Per/Polyfluoroalkyl Substance Background with Agilent 1260/1290 Infinity (II) LC’s (5991-7863EN)
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PFAS Analysis – LC SetupEliminate Background Contamination
PFAS Instrument SetupBackground Contamination
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Actual PFOS peak
5 ng/L standard
Mili-Q Water (‘Blank’)
Background PFOS from LC system
• The use of a Delay column is convenient when running multiple methods on the same instrument.
• “Delay” column and not a “Trapping” column. I.e. the background peak will be retention time separated but will be present.
• The delay column does not account for any contamination after the pump (the autosampler)
250 mL sample collected in Polypropylene Bottles with 5 g/L Trizma (to quench residual chlorine)
Solid Phase Extraction and evaporation to final 1 mL extract in ~96/4 MeOH/Water
Analysis by LC-MS/MS in Negative Electrospray mode for 14 analytes (9 PFCAs, 3 PFSAs, 2 FOSAAs) – 37 min analysis (10 µL injection)
EPA 537: Perfluorinated Alkyl Acids in Drinking Water by SPE-LC/MS/MS
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Confidentiality Label
Solid Phase ExtractionUSEPA 537 vs Modified
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Recoveries calculated in Reagent Water
Modified SPE cartridge: Agilent SampliQ WAX cartridge (6 cc, 150 mg)
All recoveries between 70-130 %
Spiking concentrations:
Modified SPE: 4 ng/L in 250 mLEPA 537: 5-21 ng/L in 250 mL
Final extract: 1 mL ~95% MeOH
PFHxA
PFHpA
PFOA
PFNA
PFDA
PFUdA
PFDoA
PFTrDA
PFTeDA
PFBS
PFHxS
PFOS
N-MeF
OSAA
N-EtFOSAA 0
25
50
75
100
125
150EPA 537 (n=7)Modified SPE (n=6)
Rec
over
y (%
)
Agilent ASTS-Houston
Typical LC/TQ Lab Layout
6 feet1.83 meters
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Quick Change Ion Injector
Fast Ion Injector exchange without system venting
Ion Injector Tool VacShield
Easy to use, increased throughput, less downtime for maintenance
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Easy Change Detector Assembly
Analysis of PFAS in Drinking Water with UltivoEPA Method 537
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Analysis of 17 PFASs in drinking water with <0.1 ng/mL DLs in extract (includes all comps in EPA 537)
Analysis of PFAS in Drinking Water with UltivoEPA Method 537
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PFOS - 7 Levels, 7 Levels Used, 14 Points, 14 Points Used, 0 QCs
Concentration (ng/
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Res
pons
es
3x10
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
y = 147.003489 * x + 20.563484 R^2 = 0.99890136 Type:Linear, Origin:Ignore, Weight:NonePFOA - 7 Levels, 7 Levels Used, 14 Points, 14 Points Used, 0 QCs
Concentration (ng/
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Res
pons
es
4x10
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
y = 3046.084833 * x + 1326.038272 R^2 = 0.99894706 Type:Linear, Origin:Ignore, Weight:None
PFOS PFOA
Calibration Curves from 0.1-20 ng/mL for PFOA and PFOS
Post-spike recoveries of 17 PFASs in a water sample extracted according to EPA 537 with Agilent SampliQ WAX cartridges
Ultivo Triple Quad LC/MS
• All 17 PFASs had linear calibration curves, with R2 > 0.99
• Overall recoveries were between 70–125% for both spiking levels
• %RSD was 0.3–10.8 %for all compounds at both spiking levels (1.0 μg/L and 5.0 μg/L)
Analysis of 30 PFASs in Drinking WaterAgilent 1260 Infinity II + 6470 Triple Quadrupole LC-MS
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Application Note: Analysis of Per/Polyfluoroalkyl Substances in Water Using an Agilent 6470 Triple Quadrupole LC/MS (5991-7951EN)
Chromatogram depicting MRM transitions of 30 PFASs post-spiked in a drinking water extract at 1 µg/L
Analysis of 30 PFASs in Drinking WaterAgilent 1260 Infinity II + 6470 Triple Quadrupole LC-MS
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Sensitivity (0.08 ng/L equil. In water) Precision
Analysis of Environmental Contaminants by LC-MS/MSIon Suppression Comparison by Sample Prep Method
Conventional SPEMass on Column :150 pg
Online SPEMass on Column :150 pg
Direct InjectionMass on Column :150 pg
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Agilent 6495 Triple Quadrupole LC/MSUltimate Sensitivity, Extreme Reproducibility
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8/8/2017Agilent 6495 QQQ LC/MS System
Agilent Jet Stream Hexabore Capillary Dual Ion Funnel
• Thermal gradient focusing• Efficient desolvation • Creates an ion rich zone
• Six capillary inlets• Samples x10 times more
ion rich gas
• Removes the gas but captures the ions
• Removes neutral noise
Agilent 6495 LC/TQ
Perfluorinated Alkyl Acids in Drinking Water by LC/TQCollaborative work with Suffolk County Water Authority
• 1290 Infinity LC coupled to a 6490 LC-MS/MS
• 14 PFAAs in 6 min
System
• PFOA, PFOS: <1 ng/L• Others: 1-10 ng/L• 80 µL aqueous injection
MDLs:
• Drinking Water• Surface Water• Ground Water
Matrices:
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2x10
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Cpd 9: PFHpA: -ESI MRM Frag=380.0V CF=0.000 DF=0.000 [email protected] (362.90000 -> 169.00000) Cal Std ppb 2.d
1.66 2.02
1 1
Counts (%) vs. Acquisition Time (min)0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2
Analysis of PFOA/PFOSDirect Injection; Rapid Analysis (1290 II UHPLC + 6495 LC-MS/MS)
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PFOS
PFOA
10 ng/L standard
• Use Multi-wash function!!!• PFOS sticks to needle and seat especially
with long worklists
Targeted Analysis LC-MS/MS vs LC-Q/TOF
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PFHxSPFOA
PFOS
PFHxSPFOA
PFOS0
20
40
60LC-MS/MSLC-QTOF
Con
cent
ratio
n (n
g/L)
Influent Effluent
Collaborative project with RMIT University, Melbourne (Timothy Coggan ; Prof. Bradley Clarke)
Agilent 6550 LC-Q/TOF
Suspect ScreeningPersonal Compounds Database and Library with Spectra• Custom PFAS database with 106 compounds• MS/MS spectra and Retention time data available for a subset of compounds
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Untargeted Analysis
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Untargeted AnalysisIdentification of Novel PFAS
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Inclusion list for targeted MS/MS and structural elucidation using fragment information using software tools (Molecular structure correlator)
Conclusions
Background contamination of PFASs is prevalent in ALL systems but can be fixed through systematic elimination of fluoropolymers in the LC.The Ultivo Triple Quad LC/MS offers significantly more sensitivity than
EPA 537 analysis while using a smaller footprint through several innovative technologies.The sensitive analysis of several newer classes of PFASs is possible
using the Ultivo and 6470.Rapid analysis of PFOA/PFOS and PFAAs can be performed by direct
large volume aqueous injection using the 6495 with <1 ng/L MDLs.Identification, screening and quantification of ‘emerging’ PFASs has
been shown using the Agilent LC-QTOF
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References
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5991-8156EN
5991-7951EN 5991-7863EN
5991-5669EN