Comparison of three different TOP Assay approaches for the determination of PFAS concentration in soil
- Within a project by the German Environmental Agency (Umweltbundesamt – UBA) soil samples are taken at different sites all over Germany. The concentration of 30 PFAS - 13 carboxylic acids (C4-C18), 5 sulfonic acids (C4-C10) and 12 precursor substances) - was determined in these soil samples using three different sample preparation approaches: 1) ultrasonic extraction of the soil samples with Methanol; 2) preparation of eluates to test the leaching behaviour of the PFAS and 3) TOP assays following the method published by Houtz & Sedlak. Targeted LC-MS/MS is used to determine PFAS concentration after all three preparation steps. For the TOP assay, the concentration of all 30 PFAS is compared prior to and after the oxidation reaction. Besides the ‘classic’ TOP assay, two other TOP assay approaches, the dTOP assay and the photoTOP assay, are tested and compared. First, all three TOP assay approaches will be tested on a reference soil spiked with a solution including all 30 PFAS measured inWithin a project by the German Environmental Agency (Umweltbundesamt – UBA) soil samples are taken at different sites all over Germany. The concentration of 30 PFAS - 13 carboxylic acids (C4-C18), 5 sulfonic acids (C4-C10) and 12 precursor substances) - was determined in these soil samples using three different sample preparation approaches: 1) ultrasonic extraction of the soil samples with Methanol; 2) preparation of eluates to test the leaching behaviour of the PFAS and 3) TOP assays following the method published by Houtz & Sedlak. Targeted LC-MS/MS is used to determine PFAS concentration after all three preparation steps. For the TOP assay, the concentration of all 30 PFAS is compared prior to and after the oxidation reaction. Besides the ‘classic’ TOP assay, two other TOP assay approaches, the dTOP assay and the photoTOP assay, are tested and compared. First, all three TOP assay approaches will be tested on a reference soil spiked with a solution including all 30 PFAS measured in the project. Later, soil samples taken within the the priorly described project will were tested.
This work is financed by the UBA via the ReFoPlan2021 project, FKZ372171.…

