Per- and polyfluoroalkyl substances (PFAS) regulations are tightening across drinking water, surface water, groundwater, wastewater, and sludge matrices simultaneously, pushing environmental laboratories to handle more samples at lower detection limits than their current workflows support. Velaris has drawn together analytical expertise from five specialist brands for environmental laboratories evaluating PFAS workflow options: Skalar, GERSTEL, TRACE, LCTech, and PromoChrom. The PFAS Water Resource Page covers automated solutions for solid-phase extraction (SPE), extractable organic fluorine (EOF), and adsorbable organic fluorine (AOF) across the full range of aqueous sample types.
Editor's Note: The EPA's April 2024 National Primary Drinking Water Regulation established enforceable maximum contaminant levels (MCLs) for PFOA and PFOS at 4.0 parts per trillion (ppt) each, with public water systems required to achieve compliance by April 2029 under the EPA's PFAS drinking water framework. Lab managers responsible for PFAS water testing must verify that sample preparation workflows deliver the sensitivity, throughput, and documentation needed for compliance monitoring at these levels. For labs still relying on manual SPE or running targeted analysis without a complementary screening method, the 2029 deadline creates a concrete timetable for workflow evaluation.
What makes PFAS water testing analytically challenging across different matrices?
Each water matrix introduces a distinct combination of detection limit pressure, interferent load, and sample complexity. Drinking water requires part-per-trillion sensitivity for PFOA and PFOS with minimal cleanup; surface water, groundwater, and wastewater carry organic matter, suspended solids, and competing ionic species that suppress liquid chromatography-tandem mass spectrometry (LC-MS/MS) signal if not removed in the cleanup step. Sludge matrices compound these problems with high solids loading and elevated organic fluorine backgrounds that affect both targeted analysis and sum-parameter screening approaches.
Automated sample preparation reduces two of the most common PFAS workflow failure points: analyst-to-analyst variability and inconsistent enrichment conditions. PFAS solid-phase extraction workflows depend on consistent enrichment and cleanup conditions across every sample to reach the part-per-trillion-level sensitivity current regulations require. EOF and AOF add a screening layer that measures total organofluorine content, covering fluorinated compounds that compound-specific methods do not detect.
How automated SPE standardizes PFAS sample preparation under EPA Methods 533, 537.1, and 1633A
SPE is the standard sample preparation technique for targeted PFAS water testing under EPA Methods 533, 537.1, and 1633A for multi-matrix samples. Each method passes a water sample through a sorbent cartridge that retains PFAS while letting interferents through, then elutes the concentrated extract for LC-MS/MS analysis. The challenge in high-throughput labs is running this enrichment and elution sequence consistently across dozens or hundreds of samples per batch.
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Automated SPE platforms from PromoChrom and LCTech within the Velaris portfolio handle sample loading, washing, and elution under controlled conditions, reducing manual handling and associated variability. Environmental laboratories managing high PFAS sample volumes face particular pressure at the sample preparation stage, where bottlenecks delay turnaround times and raise the risk of hold-time violations. The systems also enforce the anti-contamination protocols PFAS analysis requires:
- Solvent-wetted lines: Prevents PFAS adsorption to tubing and fittings before extraction begins.
- PFAS-free blanks: Confirms that the system itself does not contribute organofluorine background to sample results.
- Traceable chain-of-custody records: Documents every sample from extraction through analysis, supporting regulatory defensibility.
EOF and AOF: PFAS screening methods beyond targeted compound lists
Unlike targeted SPE, EOF and AOF measure total organofluorine content rather than individual PFAS compounds, capturing fluorine from PFAS and precursors that compound-specific methods miss. This distinction matters operationally: regulatory compliance monitoring requires quantifying specific listed compounds, while sum-parameter screening provides a broader picture of contamination that supports triage and prioritization decisions. Laboratories running high sample volumes across varied matrices use EOF or AOF as a first-pass filter before committing samples to full LC-MS/MS analysis.
EOF measures the organofluorine fraction extractable into an organic solvent from an aqueous sample, while AOF measures the fraction that adsorbs onto activated carbon under standardized conditions, reflecting a different and partly overlapping fraction of total organofluorine. Both techniques use combustion ion chromatography (CIC) to convert organofluorine to fluoride ion, then measure the result by ion chromatography. TRACE, a Velaris brand, makes the Xprep C-IC combustion ion chromatography system used for EOF and AOF determination in aqueous matrices.
Interested in lab health and safety?
Larissa Ram, Product Manager at TRACE, presented the Velaris webinar "PFAS Screening in Aqueous Matrices by EOF and AOF Analyses" on 25 August 2026, covering the principles of EOF and AOF analysis, the full AOF sample-preparation workflow, and method optimization for trace-level fluorine determination.
| SPE (targeted) | EOF | AOF | |
|---|---|---|---|
| Analytes measured | Individual PFAS compounds (e.g., PFOA, PFOS, PFNA) | Total extractable organofluorine | Total adsorbable organofluorine |
| Detection approach | LC-MS/MS after enrichment and cleanup | Combustion ion chromatography | Combustion ion chromatography |
| Matrix applicability | Drinking water, surface water, groundwater, wastewater | Aqueous matrices; solvent-extractable fraction | Aqueous matrices; activated carbon-adsorbable fraction |
| Regulatory relevance | Required for EPA MCL compliance monitoring | Screening; not yet a primary compliance method | Screening; referenced in ISO 18127:2026 and EPA Method 1621 |
| Key operational role | Quantification of regulated compounds | Sum-parameter screening for unknown PFAS | Broad-spectrum fluorine screening including non-extractable PFAS |
How to select the right PFAS water testing workflow for your laboratory
Environmental labs facing PFAS water testing decisions should begin by mapping current sample volumes and matrix types against the detection limits and throughput constraints of their existing preparation methods. Labs running primarily drinking water samples under EPA Methods 533 or 537.1 may find that automated SPE is the most direct upgrade path, while those handling mixed matrices or seeking a screening complement to targeted analysis should evaluate whether EOF, AOF, or both serve their reporting requirements. The Velaris PFAS Water Resource Page and Compliance Guide contain the method-specific and regulatory detail needed to support that workflow decision.
This content includes text that has been generated with the assistance of AI. For more information, view Lab Manager's AI use policy.
