Optimization of an ultrasound-assisted extraction method for the determination of parabens and bisphenol homologues in human saliva by liquid chromatography-tandem mass spectrometry

Parabens and bisphenols are endocrine disrupting chemicals (EDCs) widely used in our daily lives. The main route of human exposure to these compounds is through the diet. This makes human saliva an important matrix for identification of these contaminants and evaluation of human exposure. In this work a multiresidue method to determine the presence of methyl-, ethyl-, propyl-, isopropyl-, butyl-and isobutylparaben; and bisphenol A, B, C, E, F, M, P, S, Z, AP, AF and FL in human saliva samples has been developed. Sample treatment involves an initial step of protein precipitation in acidic medium and a second step of analyte extraction. Extraction parameters were optimized using univariant and multivariant strategies. Microwave assisted extraction (MAE) and ultrasound assisted extraction (UAE) were compared and UAE was chosen the optimal extraction technique. The compounds were analyzed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The calibration in matrix was applied and the limits of detection and quantification were from 0.1 to 0.4 ng g(-1) and from 0.3 to 1.0 ng g(-1), respectively. Accuracy was evaluated in terms of recovery (85.6 to 113.5%) with a relative standard deviation < 15% in all cases. The analytical method was successfully applied to quantify the target EDCs in ten human saliva samples, with some parabens being the most frequently detected compounds.