Headspace single-drop microextraction combined with nanodrop spectrophotometry for ultra-trace detection of ethanethiol using a suspended drop of AuNPs as a plasmonic sensor

It is challenging to achieve ethanethiol extraction, enrichment in a single-drop microextraction system, and an assay with good sensitivity and selectivity for analyzing food analytes in complex matrices. In this study, we combined headspace single-drop microextraction (HS-SDME) with nanodrop array spectrophotometry applied for ultra-trace determination of ethanethiol. A suspended drop of gold nanoparticles (AuNPs) solution was utilized for sensing ethanethiol as an acceptor phase. The thiol portion of ethanethiol molecules binds to the negatively charged AuNPs. Thus, the aim of target enrichment was attained, while matrix effects interference was also minimized. The approach can be used for the direct detection of ethanethiol in food without any sample pretreatment. The obtained range of linearity was 1–1000 µM and 100–1000 nM. The detection limits were 66.62 nM, comparable with those of previously reported methods. The method successfully determined ethanethiol in food (beverage, non-alcoholic beer, and cheese).