Simultaneous determination of four organotins in food packaging by high-performance liquid chromatography-tandem mass spectrometry.

A simple method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of organotins-tri-n-butyltin chloride (TBT), triphenyltin chloride (TPT), dibutyltin dichloride (DBT), and diphenyltin dichloride (DPT)-in plastic food packaging. Samples were prepared by ultrasonic extraction with dichloromethane, followed by dissolution in acetonitrile containing 0.1% formic acid, and purification by an MCX column. The extracts were analyzed by LC-MS/MS in multiple reaction monitoring and positive modes with a C18 column; elution was carried out with a gradient of 0.1% formic acid and methanol containing 0.1% formic acid. The limits of detection for TBT, TPT, DBT, and DPT were 0.1, 0.6, 0.8, and 0.3 μg kg(-1), respectively. The recovery of organotins in spiked samples ranged from 68% to 113% (relative standard deviation: 0.4-4.2%). The proposed method was successfully employed to identify the target analytes in plastic packaging used for milk and cake.