Investigating the uptake and fate of per- and polyfluoroalkylated substances (PFAS) in bean plants (Phaseolus vulgaris) – Comparison between target MS and sum parameter analysis via HR-CS-GFMAS

Abstract

In this study we present a screening method based on molecular absorption spectrometry to study PFAS uptake and fate in plants. To evaluate the suitability of this method we analyzed plant extracts with molecular absorption spectrometry (MAS) as well as liquid chromatography-tandem mass spectrometry (LC-MS/MS) for mass balance studies (w(F)). French bean plants (Phaseolus vulgaris) were grown on spiked soil using eight PFAS substances that vary in chain length and functional group composition. Specifically, these include three short-chained (C4-C5), five long-chained (C7-C10) as well as carbonic acids, one sulfonic acid and one sulfonic amid moieties. To investigate substance-specific PFAS uptake systematically, PFAS were spiked as single substance spike. Additionally, we studied one mixture of the investigated substances in equal proportions regarding w(F) and four PFAS mixtures of unknown composition. After 6 weeks plants were separated into four compartments. We analyzed the four compartments as well as soil for extractable organically bound fluorine (EOF) by HR-CS-GFMAS as well as for sum of ten target-PFAS by LC-MS/MS. All three short-chained PFAS perfluoro butanoic acid (PFBA), perfluoro butanoic sulfonic acid (PFBS) and perfluoro pentanoic acid (PFPeA) were determined in high concentrations mainly in the fruits of the investigated plants while long-chained PFAS perfluoro nonanoic acid (PFNA) and perfluoro decanoic acid (PFDA) were mainly determined in roots. PFBS was determined in remarkably high concentrations in leaves compartment by both quantification methods. Overall, comprehensive results of single substance spikes were in good agreement for both methods except for few cases. Hence, two phenomena were identified: For mixed PFAS spikes of unknown composition huge differences between EOF and sum of target PFAS were observed with systematically higher EOF values. Overall, both methods indicate comparable results with MS being more reliable for known PFAS contamination and MAS being more valuable to identify PFAS exposure of unknown composition.