Standards Development

Scope

This document specifies a method for the determination of the dissolved fraction of selected perfluoroalkyl and polyfluoroalkyl substances (PFAS) in non­filtrated drinking water using liquid chromatography­tandem mass spectrometry (LC­MS/MS). The applicability of the method to other types of water like fresh waters (e.g. ground water, surface water) or treated wastewater can be validated separately for each individual case.

For each target compound both, eventually occurring branched isomers and the respective nonbranched isomer, are quantified together. The selected set of substances determined by this method is representative for a wide variety of PFAS. This method has been validated for the analytes specified in Table 1. The list given in this table can be modified depending on the purpose and focus of the method. The lower application range of this method can vary depending on the sensitivity of the equipment used and the matrix of the samples. For many substances to which this document applies a limit of quantification (LOQ) of 1 ng/l can be achieved. Using high volume direct injection as described in part A or SPE as described in part B of the method allows lower LOQs. Analytical limitations can occur with short­chain PFAS or PFAS with more than ten carbon atoms in the carbon chain. Actual LOQs can depend on the blank values realized by individual laboratories as well.

NOTE This document enables the analysis of those 20 PFAS which are listed in point 3 of Part B of Annex III of the EU Drinking Water Directive, EU 2020/2184 [4], for the surveillance of the parametric limit value of 0,10 µg/l for the sum of PFAS.

Furthermore, alternatives and substitutes for these PFAS substances can be analysed using this document as well.

Table 1 ­ Analytes for which a determination was validated in accordance with this method

Purpose

Proposed amendment in 9.6.1 on General requirements for calibration.

The sentence "Internal standard calibration is mandatory when the internal standards are available." should be changed to read:

"Internal standard calibration is recommended, if the internal standards are available." According to Data on 150 different samples from a German laboratory, the recovery of the internal standards was determined and it can be deduced from the results that this strict requirement is not absolutely necessary (see enclosed data).