Out-of-the-box workflow for PFAS quantitation using a triple quadrupole approach with the TSQ Altis Plus mass spectrometer

Importance of the topic

Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative synthetic chemicals found across environmental compartments and human tissues. Accurate, sensitive, and robust quantitation of PFAS in water matrices is essential for public health surveillance, regulatory compliance, and remediation decision-making. Growing European regulatory requirements for drinking, surface, and groundwater demand reliable analytical workflows capable of analysing broad PFAS panels at trace concentrations while being compatible with common sample-preparation techniques.

Goals and study overview

This application brief presents a ready-to-use LC–MS/MS workflow based on the Thermo Scientific TSQ Altis Plus triple quadrupole mass spectrometer for quantitation of 61 PFAS in methanolic extracts. The objective was to demonstrate method performance (LOQ, linearity, accuracy, precision, robustness) for extracted water samples (drinking water, surface water, groundwater, wastewater) and to show compatibility with standard concentration/preparation approaches such as solid-phase extraction (SPE) and dispersive liquid–liquid microextraction (DLLME). The scope also included problematic analytes (e.g., fluorotelomer alcohols (FTOHs), FTAB) analyzed within the same chromatographic run.

Analytical methodology

Overview of the analytical strategy:

• Reversed-phase UHPLC separation using methanol and water mobile phases, both modified with 0.1 mM ammonium fluoride.
• Targeted tandem MS acquisition using multiple reaction monitoring (MRM) with two MRM transitions per compound (quantifier plus qualifier) and 1-minute retention time windows.
• Calibration in methanol over multi-level ranges (commonly 25–5,000 ng/L) with 22 labelled internal standards added at 500 ng/L to compensate for matrix and extraction variability.
• Limits of quantitation established in solvent and assessed for matrix extracts concentrated by typical enrichment factors (e.g., 500× for SPE).

Key validation criteria and QC approach:

• Linearity: R² ≥ 0.990; back-calculated concentrations within ±20% (±40% at LOQ).
• LOQ precision: RSD <20% for 10 replicate injections; LOQ bias <40% (solvent).
• Internal standard variation acceptance: RSD <30% across calibration.
• Routine QC injections: a QC at the LOQ injected every 10 matrix extracts during robustness testing.

Used instrumentation

Primary hardware and configuration used in the workflow:

• Thermo Scientific Vanquish Flex Binary UHPLC system (two pumps) with Vanquish Duo autosampler.
• Vanquish Flex column compartment operated at 55 °C.
• Analytical columns: Thermo Scientific Hypersil GOLD 50 × 2.1 mm and 100 × 2.1 mm, 1.9 µm particle size.
• Delay column installed between pump and autosampler to reduce mobile-phase and system background PFAS contamination.
• Thermo Scientific TSQ Altis Plus triple quadrupole mass spectrometer equipped with HESI source operated in negative polarity.
• Acquisition: MRM with Q1 resolution 0.7 FWHM and Q3 resolution 1.2 FWHM; 10 µL injection volume; 13 min total run time.

Main results and discussion

Linearity and dynamic range:

• Calibration performance was consistent across at least five validated curves per analyte, with R² values typically >0.999 and meeting the stated back-calculated criteria across the dynamic ranges (commonly 25–5,000 ng/L; some compounds required higher LOQs).

Sensitivity and LOQs:

• Solvent LOQs for the 61 compounds ranged typically from 50 to 250 ng/L (50 ng/L for most analytes; some FTOHs and certain amides required higher LOQs up to 500 ng/L).
• When applying typical sample pre-concentration (e.g., 500× SPE concentration), equivalent matrix LOQs were in the range of approximately 0.1–1 ng/L, compatible with EU drinking-water thresholds (0.1 µg/L for sum of 20 PFAS and 0.5 µg/L for total PFAS) and many local legislations.
• Practical sensitivity in the laboratory is constrained by ambient PFAS background; LOQs should be set relative to an individual laboratory’s contamination baseline (PFBA, PFPeA, and some N-alkylated species can appear as background).

Robustness and repeatability:

• Robustness was tested by analysing 40 matrix extracts with QCs at LOQ injected every 10 samples over a 17-hour, 70-injection sequence without MS tuning or maintenance. Results showed stable quantitation: relative amount deviations were well within acceptance limits (<40% at LOQ; <20% at higher levels), and LOQ reproducibility met RSD criteria.
• The approach demonstrated consistent performance across matrices including SPE extracts of surface water, DLLME extracts of sewage water, groundwater, and effluent.

Chromatographic coverage and challenging analytes:

• The method achieves chromatographic separation sufficient to resolve linear and branched isomers for compounds such as PFHxS and PFOS and accommodates diverse chemotypes including diPAPs, FTOHs, FTABs, FTS/FTU species, and sulfonates within a single run.

Benefits and practical application

Operational advantages:

• Ready-to-run workflow with instrument methods, data processing templates, and example datasets to speed user adoption and method transfer.
• Compatibility with standard sample-preparation techniques (SPE and DLLME) and concentration factors required by regulatory monitoring.
• Reliable targeted quantitation for a broad PFAS panel (61 compounds) with demonstrated robustness and regulatory-aligned performance.

Use cases:

• Routine monitoring of drinking water, groundwater, surface water, and wastewater for compliance and surveillance.
• Screening and targeted quantitation in environmental and industrial monitoring programs where rapid, robust results are required.

Future trends and potential applications

Emerging directions to enhance PFAS analysis and laboratory practice:

• Expansion of target lists and regular updates to cover newly regulated or emergent PFAS chemistries as regulations evolve at national and EU levels.
• Further reduction of laboratory PFAS background via PFAS-free consumables, dedicated low-background sample paths, and optimized delay-column strategies to lower method LOQs.
• Increased automation of sample-preparation workflows (SPE and DLLME) to improve throughput and reproducibility.
• Integration of targeted triple-quadrupole workflows with high-resolution suspect-screening (HRMS) to detect non-target PFAS and transformation products.
• Standardization across laboratories for QC materials, isomer assignment, and reporting to support comparability of monitoring data for regulatory and risk-assessment purposes.

Conclusions

The presented TSQ Altis Plus-based workflow provides a validated, robust, and sensitive targeted method for quantifying a comprehensive panel of PFAS in methanolic extracts from environmental waters. It meets stringent linearity and precision criteria, is compatible with standard enrichment procedures to achieve low ng/L matrix LOQs, and is engineered for practical laboratory deployment with documented methods and QC practices. The workflow supports regulatory compliance and environmental surveillance and can be adapted as regulatory target lists and monitoring needs evolve.

References

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2. Fenton SE, et al. Per‐ and polyfluoroalkyl substance toxicity and human health review: current state of knowledge and strategies for informing future research. Environmental Toxicology and Chemistry. 2021;40(3):606–630.
3. Directive (EU) 2020/2184 of the European Parliament and of the Council on the quality of water intended for human consumption. 16 December 2020.
4. Johanson S, et al. Policy briefing: Toxic tide rising: time to tackle PFAS – National approaches to address PFAS in drinking water across Europe. European Environmental Bureau. 12 October 2023.
5. US EPA. Drinking Water Research Methods (EPA documentation).
6. Thermo Fisher Scientific. Application Note 002902: Direct injection of drinking water for the analysis of 54 PFAS compounds by LC–MS/MS aligned with current and evolving global regulations.
7. Thermo Fisher Scientific. Application Brief 003164: Dispersive liquid–liquid microextraction for the automated sample preparation of PFAS in drinking water.
8. Thermo Fisher Scientific. Application Note 73883: Determination of PFAS in drinking water using automated solid-phase extraction and LC–MS/MS for U.S. EPA Method 533.
9. Thermo Fisher Scientific. Application Note 73346: Determination of PFAS in drinking water using automated solid-phase extraction and LC–MS/MS.
10. Thermo Fisher Scientific. Application Brief 003940: Out-of-the-box workflow for PFAS quantitation using a targeted approach with the Orbitrap Exploris MX mass spectrometer.