The effect of Per- and polyfluoroalkyl substances, or PFAS, on human and environmental health is one of the most widespread and complex challenges our planet faces this century. In this interview, Dr Kelly Cheshire, LGC Standards’ Global End Market Manager for Environment and Forensics, talks to us about the vital importance of optimising reference materials and calibration strategies for PFAS testing laboratories - and how labs can resolve complex analytical challenges like adsorption, matrix effects, peak resolution, and stability.
Kelly, why are PFAS such a concern in environmental and human health?
PFAS are highly stable and water soluble, allowing them to travel long distances and persist in water, soil, air, and food chains. Their stability leads to bioaccumulation and biomagnification, which ultimately impacts ecological and human health because of their long half-lives, and links to serious conditions like endocrine disruption, cancers, and cardiovascular diseases.
What makes PFAS testing so challenging?
There are many factors that make it challenging, but two key areas would be regulatory limits and matrix effects. PFAS regulatory limits are often at parts per trillion levels, which require highly sensitive instruments and accurate testing. Matrix effects, where sample composition interferes with detection, are also a major hurdle across diverse sample types - like soil, fish tissue, and wastewater.
How do labs overcome matrix effects in PFAS analysis?
One effective strategy is isotope dilution. By using labelled compounds that behave like native analytes, labs can correct for matrix interference and improve the accuracy of their identification and quantification.
Why is peak resolution important in PFAS testing?
PFAS compounds often have similar structures, so overlapping peaks can lead to misidentification and mis-quantification. This means that high resolution separation is essential for obtaining reliable data.
How do you design effective PFAS reference materials?
We tailor concentrations based on each compound’s ionisability and response in mass spectrometry. Uniform concentrations don’t work - because some compounds need higher levels to be detectable, while others saturate detectors easily.
What role does stability play in reference materials?
Stability is critical. PFAS can degrade through reactions like esterification or hydrolysis. So we use specific solvents and modifiers to prevent this and ensure that our standards are reliable in the long term.
Are there issues with PFAS adsorbing onto container surfaces?
Yes, especially at low concentrations, and the impact is even more pronounced when dealing with one analyte versus multiple analytes. Using consistent containers and matrices for both standards and samples helps to reduce surface absorption and maintain accuracy.
How do calibration strategies affect PFAS testing efficiency?
Calibration curves must account for compound sensitivity. We adjust concentrations, doubling or increasing by factors of five or 10, to ensure uniform response and streamline the calibration process.
Does instrument choice impact PFAS analysis?
Absolutely. Different instruments and ionisation sources affect compound response. Method optimisation, including column selection and separation quality, is key to accurate results.
What are the main takeaways for labs working with PFAS?
Optimising reference materials and calibration strategies is essential. Understanding PFAS behaviour, mitigating matrix effects, and ensuring stability all contribute to accurate, efficient testing and help to ensure regulatory compliance.
LGC Standards – supporting your laboratory’s PFAS compliance
To help protect human and environmental health, and to align themselves with fast-evolving PFAS regulation, laboratories must be able to amend their analytical procedures constantly. LGC Standards’ portfolio of more than 500 high-quality PFAS products, including over 80 SILs, is designed precisely to help you adapt to these regulatory and scientific developments.
Our range includes more than 300 Dr Ehrenstorfer PFAS reference materials certificated to ISO 17034 or ISO 17025 – among them the groundbreaking PFASiMix kit, which improves your laboratory’s efficiency with its mix of 27 PFAS analytes, designed for maximum stability.
To further support your analysis, we provide ready-to-use mixtures created specifically to address key PFAS regulations – such as the EU Drinking Water Directive, EU Groundwater Directive, UK DWI, UCMR5, EPA Method 533 and 537.1, as well as EPA Method 1633.
In tandem with our reference materials offering, AXIO Proficiency Testing provides a range of PFAS PT schemes that are designed to assess and improve your laboratory’s analysis of PFAS in soil, potable water, surface water and groundwater, as well as food and beer.
Meanwhile, our extensive TRC range of analytical standards and research chemicals facilitates wide-ranging PFAS analysis – including research into their potential harmful effects.
Lastly, should you require a custom molecule, why not speak to one of LGC’s expert scientists, who have more than 40 years’ experience in working through some of the most complex synthetic pathways, to deliver you the high-quality research chemicals you need.
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