Reliable quantification of bisphenol A and its chlorinated derivatives in human urine using UPLC–MS/MS method

Bisphenol A (BPA), a widespread man-made chemical classified as an endocrine disruptor, is increasingly considered as a major cause of concern for human health. Chlorine present in drinking water may react with BPA to form chlorinated derivatives (ClxBPA), which have demonstrated a heightened level of estrogenic activity. If many epidemiological studies report that more than 90% of people have detectable BPA levels in their urine, then no such study has been undertaken regarding ClxBPA. The purpose of this work is to propose a highly sensitive and accurate analytical method adapted to large-scale biomonitoring studies aimed at assessing exposure to BPA and ClxBPA through the use of human urine. To achieve this, we have comprehensively validated a method using salting-out assisted liquid/liquid extraction (SALLE) coupled to UPLC–MS/MS and isotope dilution quantification, to measure unconjugated BPA and ClxBPA in human urine according to the accepted guidelines. Deutered BPA as well as deutered 2,2′-DCBPA was used as internal standards. The matrix calibration curve ranged from 0.05 to 1.60 ng mL−1 and from 0.5 to 16.0 ng mL−1 for ClxBPA and BPA respectively, and provided good linearity (r²>0.99). This method was precise (the intra- and inter-day coefficients of variation were <20% at three different concentrations: 0.05 ng mL−1, 0.2 ng mL−1, 0.8 ng mL−1 and 0.5 ng mL−1, 2 ng mL−1, 8 ng mL−1 for ClxBPA and BPA, respectively) and accurate (bias ranged from −13% to +12%). The limit of quantification, validated at 0.05 ng mL−1 and 0.5 ng mL−1 for ClxBPA and BPA respectively when using 300 µL of urine, was found to be suitable for the concentration existing in real samples. The matrix effect and the BPA cross-contamination were also investigated in this study. The analytical method developed in this study is in accordance with the requirements applicable to biomonitoring of BPA and ClxBPA in human urine.