GEN-MKT-18-7897-A
Apr 17, 2026 | Blogs, Environmental / Industrial, Food / Beverage | 0 comments
Read time: 7 minutes
Ultra‑low reporting limits, expanding target lists, and the constant risk of background contamination mean that even small missteps before injection can compromise data integrity. PFAS can be introduced at nearly every stage of prep, from sampling containers and PPE to SPE cartridges, filters, solvents, and lab consumables, making contamination control as critical as analyte recovery.
That’s why this two-part blog series brings together to answer the most common questions labs face when designing PFAS‑ready workflows from sample preparation and beyond. Phenomenex, will focus specifically on practical strategies to reduce background contamination, select fit‑for‑purpose consumables, and the implementation of SPE approaches that meet regulatory expectations without introducing unnecessary variability.
A good starting point is to anchor yourself to the regulatory or regional method that best matches your matrix. For drinking water, that typically means alignment with EPA Method 533 or EPA Method 537.1 in the U.S., while in the EU, drinking water work often aligns with EN 17892. For multi-matrix environmental work, EPA Method 1633A is quickly becoming the default, especially for compliance-driven data.
Across all of these, a few things are non-negotiable. PFAS will adsorb to glass, so polypropylene (PP) vials are essential. PTFE is itself a PFAS material, so it must be completely avoided in the flow path and consumables to prevent false positives. And perhaps most importantly, every consumable needs to be screened, routine blank testing isn’t optional, it’s foundational.
To support this, some chromatography manufacturers, such as Phenomenex, . These are generally preferred over standard lab supplies, as they help reduce the risk of introducing background contamination and false positives without adding extra method complexity.
With these baseline controls in place, the degree of flexibility then depends heavily on the method. For drinking water analysis in the U.S., both 537.1 and 533 are approved, but 533 is increasingly preferred. The use of isotope dilution provides much better correction for matrix effects, and the analyte panel tends to be more relevant,537.1 often yields a high number of non-detects. Regulatory trends are clearly shifting toward 533.
Interestingly, both methods give you room to optimize your analysis, column chemistry, dimensions, and gradients can be tailored. But sample preparation is another story: SPE is tightly locked down. While 533 mandates weak anion exchange (WAX) with specific constrains like pKa>8 and define particle size, 537.1 requires , a surface-directed bulk layer chemistry approach that enhances selective extraction and adsorption of PFAS from complex matrices.
For non-drinking water matrices (e.g., wastewater, groundwater, soils, sediments) things broaden a bit. EPA Method 1633A allows flexibility in LC conditions but is extremely prescriptive in sample prep. You must use both WAX and graphitized carbon black (GCB), and even the order matters: aqueous samples go WAX → GCB, while solids go GCB → WAX. On top of that, QC requirements are stringent, for example, resolving PFOS from interfering cholic acid species is mandatory to avoid positive bias.
There are also direct injection approaches like EPA Method 8327, EPA Method 8328, and ASTM D8421. These eliminate SPE entirely, which simplifies workflows, but they come with trade-offs: higher detection limits, greater susceptibility to matrix effects, and the need for LC systems capable of large-volume injections.
Closing takeaway: The method you choose is largely dictated by matrix and regulatory expectations, but regardless of flexibility in LC conditions, sample prep and contamination control are where PFAS methods are least forgiving and most critical. This is also where choices like using PFAS-verified consumables can make a practical difference in avoiding background contamination and false positives.
PFAS contamination can occur at any stage and could come from a variety of sources.
At the sampling stage, the human factor is a major contributor. Clothing with water-resistant coatings, personal care products, and ambient dust can all introduce PFAS. Sampling containers also pose a risk, which is why field blanks are essential. Mitigation relies on strict sampling protocols, including lab-approved PPE, hair nets, and minimizing overall exposure pathways.
During sample preparation, contamination can originate from consumables such as syringe filters, pipette tips, vials, and SPE cartridges. To reduce this risk, it is always recommended to use consumables that have been verified to have low background levels or confirmed absence of PFAS (Check Phenomenex Designed for PFAS Portfolio). Carryover from these materials, particularly after exposure to high-concentration samples, is a common issue.. Routine blank testing is the most reliable way to keep this under control.
Additionally, PFAS can be found in LC pumps and fittings, as well as in mobile phase components, and these can lead to high bias in quantitation. While the best option is to find PFAS-free solvents and salts for mobile phases, this is not always easy to do, so delay columns are a mitigating strategy. Delay columns are placed after the pumps/mixers, and before the injector, to detect any PFAS in the mobile phase or from pump seals and fittings. This effectively “delays” any PFAS from the mobile phase or LC pumps so that these compounds are eluted later in the run, and do not interfere with the analytical peaks.
Closing takeaway: Most PFAS issues do not originate from the sample itself, but from surrounding materials, handling, and occasional system-derived contamination introduced during analysis. Without strict control of blanks and consumables verified for low background or absence of PFAS, data integrity cannot be ensured.
Sample preparation involves navigating trade-offs in the method. More prep can dramatically improve data quality, but it also introduces new risks.
The SPE technique is used to remove matrix interferences and concentrate analytes, improving both sensitivity and robustness, but every additional step in the process is an opportunity for contamination or analyte loss, PFAS binding to filter membranes is a classic example.
For most regulatory work in the United States, SPE is still the standard, with WAX as the dominant chemistry due to the acidic/anionic nature of many PFAS compounds. EPA Method 1633A goes further by requiring GCB cleanup as well, with matrix-dependent sequencing.
From a workflow perspective, traditional offline SPE using vacuum manifolds is still widely used. It’s relatively cost-effective per sample but time intensive. Automation options exist. For large volumes, systems from companies like PromoChrom Technologies or Horizon Technology are available, while CTC Analytics provides solutions for smaller-scale workflows. However, these options come with higher upfront costs.
Online SPE is an attractive alternative. Using high-pressure trap columns, it reduces hands-on time and can lower per-sample costs over time. However, it limits sample volume and therefore analyte loading, and requires more complex instrumentation, switching valves, additional pumps, and careful method design.
Direct injection methods sit at the other extreme. They’re fast, simple, and reduce contamination risk, but they demand very sensitive instruments and robust LC hardware capable of large injection volumes. They also tend to shorten column lifetime due to matrix loading and clogging.
Closing takeaway: There’s no universally “best” prep, only trade-offs. In PFAS work, the right choice is the one that meets sensitivity needs without introducing more variability or contamination than it removes.
In practice, a PFAS-ready method is less about a single configuration and more about a set of deliberate choices that work together.
It starts with controlling background. Delay columns should be selected based on the retention behaviour of your analyte panel, ensuring that any PFAS originating from solvents or the LC system is separated from your target compounds.
Chromatography then becomes a balancing act between sensitivity, resolution, and runtime. Column dimensions, particle size, and stationary phase all influence peak shape and height, especially for early-eluting compounds that are often the hardest to retain and quantify reliably.
On the MS/MS side, negative electrospray ionization is used, with carefully selected transitions to ensure both sensitivity and selectivity. Method design should focus on the target analyte list while maintaining robust quantitation through isotope dilution wherever possible.
Finally, long-term consistency is what separates a functional method from a reliable one. This means stable retention times, controlled background levels, and QC systems that continuously verify performance, especially for known interferences like those highlighted in EPA Method 1633A.
Closing takeaway: A PFAS-ready system isn’t defined by a single setting, it’s defined by how well background, separation, and consistency are controlled over time.
Keep an eye out for Part Two of this blog series, where SCIEX PFAS expert Craig Butt will take you through the rest of the workflow, covering how to optimise LC‑MS/MS performance, maintain long term robustness, and ensure confidence in PFAS results from injection to reporting. You will learn about what it really takes to get PFAS right across the full analytical workflow.
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