In what many scientists believe will be a significant advancement in analytical testing methodology, ASTM is planning to release a new Standard Test Method for PFAS in aqueous sample matrices. This new method, ASTMD8421-21, utilizes Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) with Isotope Dilution (ID).
It is anticipated to be the first published ASTM method for PFAS that incorporates isotope dilution in the actual method and not simply a footnote. This is significant because of the advantages associated with isotope dilution, including minimizing sample matrix interference and improving data quality. ASTM states that ASTM D8421-21 is a robust method to quantitatively determine PFAS compounds at trace levels in water samples.
Merit Laboratories has been performing a method identical to ASTM D8421-21, with experience analyzing thousands of samples for PFAS. Reporting limits provided by Merit Laboratories are typically up to five times lower than those listed in this newly-released ASTM method.
Merit was able to consistently demonstrate much better recoveries for all PFAS compounds. The better recoveries are partly attributed to much less sample handling. Sample handling can both contaminate and remove compounds of interest in your samples. There are other key advantages for using this method, including better recoveries for all PFAS compounds; less sample handling; significantly less chance of contamination or analyte loss; more consistent results; and simpler sample preparation.
The sample holding time for ASTM D8421-21 is 28 days. The method was validated using reagent water and waters from multiple sources and types, including landfill leachate, POTW effluent and influent, and paper mill effluent.
Merit Laboratories is a leading national PFAS environmental laboratory, analyzing drinking water, soil, wastewater, groundwater, and other sample matrices, including biosolids and sludge. Analytical methods performed by Merit for PFAS include drinking water by EPA 533, EPA 537.1, and EPA 537 rev. 1.1, biosolids by ASTM D7968-17 with Isotopic Dilution, and soil, wastewater, groundwater, and surface water by ASTM D7979-19 with Isotopic Dilution and ASTM D7968-17.