Phthalates and bisphenol A (BPA) have received special attention in recent years due to their frequent use in consumer products and potential for adverse effects on human health. BPA is being replaced with a number of alternatives, including bisphenol S, bisphenol B, bisphenol F and bisphenol AF. These bisphenol analogues have similar potential for adverse health effects, but studies on human exposure are limited. Accurate measurement of multiple contaminants is important for estimating exposure. This paper describes a sensitive and automated method for the simultaneous determination of 14 phthalate metabolites, BPA and four bisphenol analogues in urine using online solid phase extraction coupled with high-performance liquid chromatography/tandem mass spectrometry using a hybrid triple-quadrupole linear ion trap mass spectrometer (LC-QTRAP-MS/MS), requiring very little sample volume (50µL). Quantification was performed under selected reaction monitoring (SRM) mode with negative electrospray ionization. The use of SRM combined with an enhanced product ion scan within the same analysis was examined. Unequivocal identification was provided by the acquisition of three SRM transitions per compound and isotope dilution. The analytical performance of the method was evaluated in synthetic and human urine. Linearity of response over three orders of magnitude was demonstrated for all of the compounds (R(2)>0.99), with method detection limits of 0.01-0.5ng/mL and limits of reporting of 0.07-3.1ng/mL. Accuracy ranged from 93% to 113% and inter- and intra-day precision were <22%. Finally, the validated method has been successfully applied to a cohort of pregnant women to measure biomarker concentrations of phthalates and bisphenols, with median concentrations ranging from 0.3ng/mL (bisphenol S) to 18.5ng/mL (monoethyl phthalate).
Keywords: Biomonitoring; Bisphenol A; Bisphenol analogues; LC–MS/MS; On-line solid phase extraction; Phthalates.
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