Optimisation of the conditions of dispersive liquid–liquid microextraction for environmentally friendly determination of bisphenols and benzophenone in complex water matrices by LC-MS/MS

Abstract

Due to well-known risks to human and environmental health, the increasing presence of several micropollutants even in very low concentrations in environmental matrices requires sustainable and advanced analytical methods to expand monitoring programs, particularly for water quality control. The objective of this study was to optimise the conditions of the dispersive liquid–liquid microextraction (DLLME) for a combined group of emerging micropollutants (bisphenol A, bisphenol S, bisphenol F, bisphenol AF and benzophenone) in complex water matrices. Ten variables were chosen as the most important for DLLME procedure and the Design of Experiments (DoE) approach was applied to find the most relevant variables and optimise the DLLME procedure. The optimised DLLME was then, applied to real complex water samples including raw and treated wastewaters and surface water in Rio de Janeiro city, Brazil, and the extracted samples were analysed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The variables vortex mixing time (VMT), Dispersive Solvent Volume (DSV) and Extractor Solvent Volume (ESV) are the most important among the variables evaluated. The recovery efficiencies ranged from 60 to 120% after optimisation the amounts of target compounds found in the five real aqueous matrices varied from 0.005 to 150 μg L-1. The association of optimised DLLME with the UPLC-MS/MS met the validation requirements adopted and generated analytical results of high quality. The advantages of this extraction technique include reduction of cost per analysis; low volume of samples and low volume of solvent required; no need to use cartridges; reduction of waste generation. The method is, therefore, suitable to process large numbers of samples, particularly in countries with limited budgets for environmental monitoring.