A polydimethylsiloxane/deep eutectic solvent sol-gel thin film sorbent and its application to solid-phase microextraction of parabens.

A novel, efficient and reproducible thin-film solid-phase microextraction method using the polydimethylsiloxane/deep eutectic solvent sol-gel as coating material was developed for preconcentration of parabens from environmental samples. New sorbent materials consisting of polydimethylsiloxane with nine new synthesized deep eutectic solvents were prepared by the sol-gel method, and these materials were used to prepare thin film coatings on a mesh support. Among obtained compounds, the highest efficiency in the extraction of parabens was demonstrated by a sorbent consisting of trihexyltetradecylphosphonium chloride and n-docosanol in a molar ratio 1:2 mixed with polydimethylsiloxane. For the proposed method, the parameters affecting the extraction efficiency of parabens were optimized, including the coating material type based on polydimethylsiloxane/deep eutectic solvent, the sample volume, the salting-out effect, the pH of the sample, the extraction time, the desorption solvent and time. The limits of detection and quantitation were from 0.023 to 0.062 ng mL and 0.076-0.201 ng mL, respectively, and the enrichment factors ranged from 174 to 186. Under optimal conditions, the proposed method based on measurements for river and lake water achieved good precision between 2.7 and 5.9% and recovery ranging from 79.1 to 88.1%. The developed method was successfully applied to determine trace levels of parabens in the samples of surface waters collected from rivers and lakes.