Perfluorinated carboxylic acids (PFCAs, C7-C12) through the biogeochemical cycle of grapevine: determination by GC/MS after derivatization

In recent years major efforts have been undertaken to study the so-called emerging pollutants, an heterogeneous group of chemical substances which have been recently discovered or which are spreading wider. In particular, perfluoroalkyl substances (PFASs) attracted increasing interest due to their widespread applications, environmental persistence and bioaccumulative potential, becoming a possible threat for human health. PFASs are a large group of anthropogenic organic chemicals widely used for a variety of industrial applications. Their unique physico-chemical and biological properties make them resistant to hydrolysis, photolysis and biodegradation, as well as to metabolic processes in living organisms. Unlike other persistent organic pollutants (POPs), PFASs are water-soluble, hence easily released into surface water and aquifers, which become the principal medium for their environmental transport [1]. For this reason, they can enter into the food chain through the reuse of this water to irrigate crops, intensifying the possible human exposure to PFASs. In the last few years, a serious PFAS pollution is affecting a large area of the Veneto region, Italy, among the provinces of Vicenza, Verona and Padua (about 350.000 inhabitants), caused by industrial discharges that have contaminated the rivers, the aquifers and the drinking water (PFAS concentrations up to 428 ng L-1) [2]. In this contest, the aim of the present research is to determine the occurrence and the concentration levels of six perfluorinated carboxylic acids (PFCAs) in soils of two different Venetian vineyard (Vitis vinifera, L. 1753, cv. Glera, Garganega and Cabernet-sauvignon). In order to study whether and how these pollutants move from the irrigation water to the soil and plants, the presence of PFCAs in roots, leaves and fruits sampled during the entire vegetative cycle of grapevine (from the budding period to the grape harvest) was also determined. PFCAs were analyzed using a GC/MS instrumentation adopting a rapid and simple derivatization procedure in acetonitrile proposed by Dufková et al. [3-4], using isobutyl chloroformate to convert the acids into the more volatile isobutyl esters under catalysis by pyridine. The extraction of the analytes from the different matrices was performed using an ion-pairing ultrasound-assisted procedure in methanol or employing a SPE pre-concentration technique. Quantification was performed using internal standards and the isotopic dilution technique. Results were corrected using the instrumental response factor. [1] Prevedouros et al., 2006. Environ. Sci. Technol. 40, 32-44. DOI: 10.1021/es0512475. [2] ARPAV, Veneto Regional Environmental Protection Agency, 2017. http://www.arpa.veneto.it/. [3] Dufková et al., 2009. J. Chromatogr. A 1216, 8659-8664. DOI: 10.1016/j.chroma.2009.10.042. [4] Dufková et al., 2012. Chemosphere 87, 463-469. DOI: 10.1016/j.chemosphere.2011.12.029.