Application of ultrasound-assisted dispersive liquid-liquid microextraction and automated in-port silylation for the simultaneous determination of phenolic endocrine disruptor chemicals in water samples by gas chromatography-triple quadrupole mass spectrometry

Abstract

An analytical methodology has been developed based on ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled to automated in-port silylation (auto-IPS) for the simultaneous determination of ten phenolic endocrine disruptor chemicals (PEDCs) which include alkylphenols, parabens and bisphenols. Optimization of DLLME parameters includes the type and volume of extraction and disperser solvent, pH, ionic strength and sonication time. Under the optimized conditions, acetone (200 μL) and dichloromethane (100 μL) were rapidly injected into 2 mL of water sample and sonicated for 90 s. After centrifugation the sedimented phase was taken into a gas chromatography-mass spectrometry autosampler vial and subjected to auto-IPS with bis(trimethylsilyl)trifluoroacetamide containing 1% trimethylchlorosilane (BSTFA + TMCS; 99 : 1 v/v). Auto-IPS parameters such as the effect of solvent, injector port temperature and the ratio of the volume of the sedimented phase to BSTFA were thoroughly studied. The PEDCs were analyzed by gas chromatography-tandem mass spectrometry in the selected reaction monitoring mode. Linearity in the range of 0.01–500 μg L⁻¹ was obtained for all the PEDCs. The limit of detection and limit of quantification were found to be in the range of 0.002–0.23 μg L⁻¹ and 0.009–0.77 μg L⁻¹, respectively. Satisfactory recoveries ranging from 82–98% were achieved for all the PEDCs. In conclusion, the coupling of UA-DLLME with auto-IPS greatly reduces the amount of solvents used for extraction, costly reagent for derivatization and time of sample preparation plus derivatization, resulting in a rapid, sensitive, economical and eco-friendly method which could be of immense use in the routine analysis of water samples for regulatory purposes.