PFAS analysis

PFAS rose to the public’s attention in the UK, in the aftermath of the 2005 Buncefield oil disaster. In order to bring this fire under control, PFOS (Perfluorooctane Sulfonate) was used as a key surfactant in hundreds of tons of firefighting foam. PFOS and PFOA were subsequently found to be present in the main aquifer below the site and further monitoring showed its presence in numerous water sources throughout the country.

In 2009, PFOS was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants. Following this, measures were taken to restrict its production and use and further restriction was also proposed for PFAS substances containing C7 or C8 perfluorocarbon chains. 

In 2013 PFOS and its derivatives were added to Annex I of the Priority Hazardous Directive (2013/39/EC). The EU surface water annual average environmental quality standard (AA-EQS) was set to 0.65ng/L and applied in 2018.

The UK Environment Agency has published Soil Screening Values for PFOS of 0.014 mg/Kg (dry weight). Similarly, the UK Drinking Water Inspectorate (DWI) guidance places a tiered risk assessment approach with a trigger value of 10ng/L on PFOS and PFOA, above which further monitoring must be undertaken. This would be based on a list of 47 PFAS chemicals which include 19 of the 20 PFAS chemicals listed in the revised European Drinking Water directive.

Following large scale monitoring programmes such as UK Chemicals Investigation Programme (CIP) and data provided by the UK Environment Agency (EA), we know that PFAS chemicals are present in the majority of our surface water bodies. The EA state that in 470 fresh water bodies monitored since 2016, only 8% of sites had concentrations below the EQS for PFOS (from 0.053 ng/L to 84 ng/L), and only 3% of estuarine and costal waters monitored were below the EQS. Furthermore, from the CIP phase 2 monitoring programme which looked at 450 Waste Water Treatment Works, 90% of samples downstream of the discharge are exceeding the EQS. Most samples upstream of the works are already at the limit or exceeding the EQS.

The RPS Bedford laboratory was one of the first laboratories in the UK to gain UKAS accreditation for the analysis of a range PFAS chemicals following the monitoring required at the Buncefield oil terminal. Our laboratory team has been instrumental in providing analytical support during the extensive remediation and clean-up project and then providing routine monitoring.

We have been providing ISO 17025 accredited analysis of both PFOS and PFOA as part of the UK Chemicals Investigation Programme for the last 12 years in line with EU AA-EQS targets and with limits of detection for both substances in water, down to 0.09ng/L. This is roughly equivalent to detecting a single drop of PFOS in 44 Olympic size swimming pools.

We carry out analysis of PFAS chemicals in line with the European Drinking Water Directive list of 20 and the UK Drinking Water Inspectorate list of 47 which we have now extended to include 51 targeted PFAS chemicals as 0.1ng/L.

As shorter chain PFASs  (<C7) are less retained by granulated activated carbon treatment systems, we have been providing analytical support to water companies, consultancies and university pilot trials in order to monitor a wide range of PFASs. This has helped our clients to evaluate their treatment options and understand the risks posed by other currently unregulated substances.

We have also been recently involved in the analysis of landfill leachate from open and closed landfill sites on behalf of the Environment Agency and the Department for Environment Food and Rural Affairs (DEFRA) to assess the potential risks of these forever chemicals from these sites. We can also provide analysis for soil, sediment, food and animal tissues.

Quality and experience

RPS has been accredited for the analysis of these chemicals since 2005 and has years of experience in the analysis of these chemicals at ultra-low levels including 12 years producing analysis data for the UK Chemical Investigation Programme as well as years of successful participation in external Performance Testing in schemes such as AQS, Aquacheck and Quasimeme.  RPS is also a member of the Environment Agency PFAS laboratory steering group which links into the wider European data sharing network.

RPS can also provide the analysis of compounds of emerging interests. For instance, Perfluoroethylcyclohexane Sulfonate (PFECHS) has been utilised extensively as a hydraulic fluid additive inhibit corrosion especially in aircraft systems. It has recently been identified as a likely source of this product in surface waters, fish and sediments in the proximity to airport facilities. As PFECHS is a technical mixture it contains over 13 constituents in varying ratios which can be determined by LC-MS/MS.

On 7 December 2022, the European Commission introduced new limits for perfluoroalkyl substances in food that would apply from 1 January 2023 onwards. Foodstuffs lawfully placed on the market before this date, could remain on the market until their date of minimum durability or use-by date.

Limits would apply to a range of food matrices as outlined in the Annex to regulation (EC) No1881/2006 in the New “Section 10: Perfluoroalkyl substances. Limits have been set for PFOS, PFOA, PFNA and PFHxS with the maximum level applying to the sum of both the linear and branched stereoisomers.

RPS can now offer analysis of these perfluoroalkyl substances (PFAS) by Ultra High-Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-QQQ) and can also supply analysis of a larger range of other PFAS if required.