Analytical Solutions for PFAS Testing

Importance of the topic

Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative, and widely used industrial and consumer chemicals. Their chemical stability and resistance to degradation have resulted in extensive environmental dispersion and human exposure via drinking water, food, air, soils, and contact with consumer products. Growing epidemiological and toxicological concerns, together with tightening regulatory limits, require analytical methods capable of trace-level detection, robust quantitation across diverse matrices, broad-target and non-target screening, and rapid high-throughput workflows to support monitoring and remediation.

Objectives and overview of the study

The document presents a suite of analytical solutions and validated workflows for PFAS testing across environmental and product matrices. Objectives include demonstrating method performance against regulatory standards (EPA, ISO, ASTM, AOAC), evaluating sensitivity and robustness of modern LC-MS(/MS) instruments, expanding analytical scope with GC-MS and combustion ion chromatography (CIC) for neutral/total-fluorine detection, and illustrating non-targeted high-resolution screening for suspect/unknown PFAS.

Methodology and analytical approaches

• Targeted LC-MS/MS: Triple quadrupole platforms and method packages conforming to EPA 537.1, 533, 544, 545, EPA 1633/1633A, ISO 21675, ASTM D8421 and AOAC SMPR for water, wastewater, soil, tissue and food matrices.
• Direct injection LC-MS: Ultra-high sensitivity direct-injection workflows to avoid SPE concentration steps for drinking water when instrument sensitivity allows.
• Non-targeted HRAM-DIA: High-resolution accurate-mass data-independent acquisition (DIA) on QTOF instruments for suspect/unknown PFAS discovery and structural characterization via deconvoluted MS/MS and library matching.
• GC-MS with thermal desorption: Measurement of volatile/semivolatile neutral PFAS (e.g., fluorotelomer alcohols) using thermal desorption (TD) coupled to GC-MS to avoid solvent extraction for air samples.
• Combustion Ion Chromatography (CIC): Adsorbable Organic Fluorine (AOF) screening following EPA 1621 to quantify total organic fluorine as a proxy for the presence of non-targetable fluorinated organics.
• Screening by EDXRF: Rapid presence/absence screening of fluorine in coatings/textiles to indicate potential PFAS treatment without extensive sample prep.

Instrumentation used

• Triple-quadrupole LC-MS/MS platforms: LCMS-8060RX, LCMS-8065XE, LCMS-8060RX, LCMS-8060NX, LCMS-8050 and LCMS-TQ RX Series (Shimadzu) for targeted quantitation.
• High-sensitivity and compact MS: LCMS-8065XE (StreamFocus ESI, UFsweeper IV collision cell), LCMS-2050 single-quadrupole for cost-effective assays.
• QTOF/HRAM instruments: LCMS-9030/9050 for HRAM-DIA untargeted screening and confirmatory analysis.
• GC-MS and thermal desorption: GCMS-QP2020 NX coupled with TD-30R for ambient air volatile PFAS.
• Combustion IC: HIC-ESP ion chromatograph coupled to AQF-5000H combustion unit for AOF (EPA 1621).
• Automated UHPLC and online SPE: Nexera UHPLC, Nexera SIL-40 autosampler (stacked injection), Nexcol PFAS Delay columns for background suppression and automated on-line SPE workflows.
• Elemental screening: EDX-8100 energy-dispersive X-ray fluorescence (EDXRF) for rapid fluorine detection in textiles and coatings.

Main results and discussion

• Drinking water (EPA 537.1): LC-MS/MS method packages analyzed 18 target PFAS with calibration linearity (R>0.997) and acceptable repeatability; spike recoveries at 1 ng/L (1/4 MCL) and at final MCLs (4 ng/L) were robust, validating method suitability for regulatory limits.
• Direct injection (LCMS-8065XE): Demonstrated quantitation of 29 PFAS by direct injection with LOQs below 1 ng/L, 18-minute cycle time, and recoveries within 80–120% and reproducibility <20% for fortified drinking water.
• Multi-method switching (LCMS-8060RX): Single-platform automatic switching allowed sequential analysis of PFAS (EPA 533) and cyanotoxins (EPA 544 and 545) with brief rinses and sustained accuracy (80–120%) and %RSD <15% across method transitions.
• Wastewater standards: ASTM D8421 implementation (44 PFAS + 24 surrogates) exceeded performance criteria; chromatographic optimizations (co-injection with weak acid, column dimensions, flow) improved peak shape for early-eluting short-chain PFAS.
• ISO 21675 results: Solid-phase extraction workflow for 30 PFAS achieved 80–119% recoveries in ultrapure water at low spikes; wastewater matrices showed variable recoveries at low spike (59–170%) due to matrix background but acceptable recovery at higher spikes (81–116%). This highlights matrix-driven bias and need for robust blanks.
• Soil and tissue robustness: LCMS-RX series achieved excellent long-run stability—500 consecutive soil injections with RSDs 4.8–6.8% for major PFAS; LCMS-8065XE provided LLOQs up to 80× lower than EPA 1633A requirements and sustained performance over 900 injections for tissue samples, with chromatographic separation resolving PFOS from interfering bile acids.
• Food matrices and automation: Validated AOAC-targeted methods quantified 30 PFAS in fish (LOQ 0.1 µg/kg) and milk (LOQ 0.01 µg/kg) with recoveries and repeatability meeting AOAC SMPR criteria. An automated QuEChERS + online-SPE workflow enabled quantification of 27 PFAS in eggs with low ng/mL sensitivity and good recoveries.
• Packaging and consumer products: Direct LC-MS/MS methods found multiple PFAS in food contact materials and fast-food packaging—levels detected were below the Danish 2015 guideline for total organic fluorine. A solvent-extraction workflow for consumer products delivered surrogate recoveries mostly within 70–130% across plastics and nonstick foil matrices.
• Ambient air (GC-MS TD): Thermal desorption GC-MS detected volatile/semivolatile neutral PFAS (FTOHs, FTACs, FOSAs) with method detection down to 0.05 ng and spike recoveries 77–106% in air sampling tubes.
• CIC AOF screening: AOF workflow following EPA 1621 delivered calibration accuracy (80–120%) and a method detection limit (MDL) of 1.27 µg/L, enabling total fluorine screening that complements targeted LC methods by revealing non-target fluorinated organics.
• Non-target HRAM-DIA: QTOF workflows identified and characterized unknown PFAS-like features; method sensitivity reached low pg/mL levels for several PFAS and mass accuracy <±3.3 ppm, enabling discovery of 16 PFAS-like species in environmental samples via mass-defect filtering, deconvolution and library matching.

Benefits and practical applications of the methods

• Regulatory compliance: Validated targeted methods meet or exceed method performance criteria across EPA, ISO, ASTM and AOAC guidance for diverse matrices.
• Operational efficiency: Direct injection and online-SPE reduce sample prep, increasing throughput and reducing labor and consumables.
• Workflow consolidation: Automatic method switching allows sequential analyses (PFAS and cyanotoxins) on a single instrument, optimizing capital use in emergency monitoring.
• Comprehensive coverage: Coupling targeted LC-MS/MS, GC-MS for volatiles, CIC for total fluorine, HRAM for non-targets, and EDXRF for rapid screening provides a complementary toolbox to capture known and unknown PFAS risks.
• Robustness: Demonstrated long-run stability and reproducibility in challenging matrices (soil, tissue, wastewater) supports routine monitoring programs and large sample batches.

Future trends and possibilities for application

• Expanded target lists and harmonized standards: Expect regulatory target expansions and harmonization across agencies; methods will need to cover shorter/longer chain PFAS and novel replacements.
• Integration of HRAM databases and AI-driven suspect screening: Larger curated libraries and machine learning will accelerate unknown PFAS identification and structural annotation.
• Field and near-real-time screening: Development of portable or simplified rapid-screening platforms for presumptive testing (e.g., CIC miniaturization, field-deployable LC/GC) to support remediation and source control decisions.
• Method automation and standardization: Greater adoption of fully automated sample prep (online SPE, stacked injections) and standardized interlaboratory protocols to improve comparability and reduce background contamination.
• Treatment evaluation and lifecycle assessment: Analytical methods will increasingly support performance evaluation of PFAS removal technologies and life-cycle monitoring of PFAS-containing products and replacements.

Conclusion

The presented analytical solutions demonstrate that modern chromatographic and mass spectrometric technologies, complemented by CIC, GC-MS thermal desorption, and EDXRF screening, can deliver comprehensive PFAS surveillance across environmental and product matrices. Key strengths are improved sensitivity (sub-ng/L to sub-µg/kg depending on matrix), high throughput enabled by direct injection and online SPE, and the ability to discover unknown PFAS via HRAM-DIA. Challenges remain in matrix interferences, background contamination, and the need for harmonized standards, but combined targeted and non-targeted approaches provide a resilient analytical framework to meet evolving regulatory and monitoring demands.

References

1. U.S. Environmental Protection Agency (EPA) Method 537.1: Determination of selected per- and polyfluoroalkyl substances in drinking water by solid phase extraction and liquid chromatography/tandem mass spectrometry (LC-MS/MS).
2. U.S. EPA Method 533, 544, 545: LC-MS/MS methods for PFAS and cyanotoxins in water matrices.
3. U.S. EPA Method 1621: Adsorbable Organic Fluorine (AOF) in water by granular activated carbon adsorption, combustion and ion chromatography.
4. EPA Method 1633 / 1633A: Targeted LC-MS/MS method for PFAS in wastewater, biosolids, soil and tissue.
5. ISO 21675: International standard for determination of PFAS in aqueous matrices.
6. ASTM D8421-22: Standard method for analysis of multiple PFAS and labeled isotopes in non-potable water.
7. AOAC SMPR documents: Performance requirements for PFAS determination in food matrices.
8. Shimadzu application notes and instrumentation descriptions for LCMS, GCMS, QTOF, CIC and EDXRF systems used for PFAS analysis.