Method development and validation for the determination of selected endocrine disrupting compounds by liquid chromatography mass spectrometry and isotope pattern deconvolution in water samples. Comparison of two extraction techniques

Abstract

In the present work two different extraction methodologies have been developed and validated for the determination of t-octylphenol and a technical mixture of nonylphenol (both, priority substances of EU water policy) and bisphenol A (BPA) in water samples. BPA was quantified by isotope dilution mass spectrometry and isotope pattern deconvolution for the first time taking advantage of ¹³C-isotopic analogues as internal standards, together with the previously studied alkylphenols. After preconcentration of the selected compounds, the samples were analyzed by ultra high pressure liquid chromatography and tandem mass spectrometry. For this purpose two extraction methodologies were proposed and compared: a routine extraction methodology based on solid-phase extraction (SPE), and a non-conventional technique based on hollow fiber liquid phase microextraction (HF-LPME). The sought methodologies were satisfactorily validated for the analysis of drinking water, surface water and effluent wastewater at two concentration levels, 0.1 and 1 μg L⁻¹ for the alkylphenols and at 0.5 and 5 μg L⁻¹ for BPA. Recoveries within 89–113% and 91–113% were obtained for HF-LPME and SPE respectively, with acceptable coefficients of variation in all cases according to SANCO guidelines. In addition, the use of isotope pattern deconvolution calculations provided the concentration of each analyte without the use of a calibration curve. Finally, a comparison of both methodologies is included, showing that while HF-LPME requires a shorter sample preparation time and the overall cost is lower, SPE extraction and manipulation is highlighted as being user friendly.