Identifying organic micropollutants' transformation products from the soil dissipation experiment by non-targeted high-resolution mass spectrometry approach: Can we gain more than transformation product identity?

Abstract

Risk assessment of environmental hazards originating from xenobiotics extensively used worldwide (e.g., pharmaceuticals, bisphenols, or preservatives) requires a combined study of their effects, mobility, dissipation mechanisms, and subsequent transformation product identification and evaluation. We have developed an efficient accelerated solvent extraction method for a broad range of micropollutants of variable physical-chemical properties in soils to enable more accurate hazard characterisation. Micropollutant recoveries from freeze-dried soils were 60–120%, with the exception of atorvastatin, fexofenadine, and telmisartan, which had reduced recoveries (40–66%). The observed matrix effect ranged from −26% to 17% and was corrected by the matrix matching standard for quantitative analysis. The method allows sensitive and reliable determination of a wide range of analytes in soil samples and, consequently, qualitative analysis of transformation products (TP) with variable physicochemical properties. We identified TPs of five compounds (venlafaxine, telmisartan, valsartan, atorvastatin, and sertraline) by applying suspect and non-targeted data analyses. To our knowledge, the transformation product of atorvastatin was reported for the first time. All others were found in soil or other matrices. Valsartan (formed valsartan acid) and atorvastatin (transformed probably by oxidative decarboxylation of beta, delta dihydroxy heptanoic acid chain to propionic acid) were modified to a relatively large extent. All other compounds identified were only hydroxylated (sertraline and telmisartan) or demethylated (venlafaxine). We estimated the stability and presence of the identified TPs based on the constructed time trends and the ratio between TP formation and degradation rates. We demonstrated how valuable a non-targeted approach can be for complex evaluation of the fate and effect of soil pollutants.