Total Oxidizable Precursors - TOP

Modified on: Thu, 28 Mar, 2019 at 10:35 AM

Precursors = compounds that may convert to polyfluorinated alkyl substances (PFAS), in situ.  These compounds either already exist in the environment as contaminants or are co-released with the target PFAS.

Total Oxidizable Precursors.  Otherwise known as TOP testing.

BV Laboratories currently provides analyses of up to twenty five (25) PFAS (including PFOS (perfluorooctane sulfonate) and PFOA (perfluoroctanoic acid)), nine (9) of which are known precursor compounds, in a diverse range of environmental matrices.

However, the results from these analyses only represent the concentrations of these twenty-five (25) PFAS at the time the sample was collected. They do not measure the potential for PFAS formation due to transformation of precursor compounds over time.

One approach to measure the potential for PFAS formation in water and soil is to apply the total oxidizable precursors (TOPs) assay.

BV Labs offers the TOPs assay on a variety of matrices, including: surface water; groundwater; wastewater; drinking water; and soils.

The TOPs assay requires that samples be collected in duplicate.
1. One part of the duplicate sample is analysed as received, for the 25 measured PFAS to establish the initial concentrations of the PFAS end products.
2. The second part of the duplicate sample is heated with an oxidizing agent under alkaline conditions to transform potential precursor compounds, both known (the nine that are monitored by the PFAS Test) and unknown, into PFAS “end products."
3. The oxidized sample is then submitted for analysis of the 25 PFAS to determine any increase in PFAS end product concentrations.
4. The difference between the initial and final concentrations of the PFAS end products represents the presence of per- and polyfluorinated precursor compounds.
Quantitative analyses of the target list PFAS and precursor compounds is performed by using isotope dilution liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS).

For additional information please review the technical bulletin PFAS-Total-Oxidizable-Precursors.


Did you find it helpful? Yes No

Send feedback
Sorry we couldn't be helpful. Help us improve this article with your feedback.