Till Örebro universitet

BACKGROUND: In most water and biological samples, the sum of target or even non-target PFAS makes up only a small fraction of the extractable organofluorine (EOF). The methods used for EOF analysis in the methanol are combustion ion chromatography (CIC) and recently high-resolution graphite furnace molecular absorption spectrometry (HR GFMAS). Water samples show a bias towards higher concentrations measured with HR GFMAS than that of CIC. Whether the bias depends on the type of PFAS or on the sample matrix has not been known. Here we study the PFAS compound and the matrix effect using HR GFMAS and compare these with the CIC results.

RESULTS: Calibration of the HR GFMAS with fluoride exhibit significant higher response than using PFOA indicating a compound specific effect. PFOA calibration gave in the average quantitative recoveries for different type of PFAS in methanol, although neutral PFAS (FTOH) show lower recoveries than PFCA using HR GFMAS. Spiked PFOA in brain and liver tissue samples resulted in quantitative recoveries (101 %) using HR GFMAS. 44 liver, kidney, blubber and brain samples from stranded pilot whales were analysed by HR GFMAS and compared to the EOF concentrations analysed by CIC. All EOF results were above the LOD of both methods; 27 and 916 ng/g (CIC) and between 77 and 3130 ng/g (HR GFMAS). In general HR GFMAS gave significantly higher results for all tissues than CIC (p > 0.05). Correlations between the EOF of all tissues showed a tissue dependant behaviour.

SIGNIFICANCE: Since PFOA recovery was in brain and liver quantitative, the results indicate that PFAS type influence the performance using HR GFMAS. Overall, we found the concentrations in the different tissues to be comparable with the two methods within one order of magnitude. This highlights the fact that more work is needed to identify the matrix effects and fluorine species dependant responses of both methods.