Determination of endosulfan isomers and endosulfan sulfate in tomato juice by matrix solid-phase dispersion and gas chromatography

A rapid method based on matrix solid-phase dispersion was developed for the determination of endosulfan isomers and endosulfan sulfate in commercial tomato juice. After the optimisation of different parameters such as the type of adsorbent, the extraction solvent, and the extraction assistance by sonication, the recoveries obtained ranged from 81 to 100% with relative standard deviations equal to or lower than 10%. The analysis of samples was accomplished using gas chromatography with electron-capture detection and the identity of endosulfan residues was confirmed by gas chromatography–mass spectrometry with selected ion monitoring. The detection limit for these compounds, calculated as three times the background noise, was 1 μg/kg. The proposed method was applied to the analysis of these compounds in commercial juice samples and levels of endosulfan between 1 and 5 μg/kg were detected in some samples.