This document describes a method for determining organotin compounds in plastic products using gas chromatography-mass spectrometry (GC/MS) after ethyl derivatization with sodium tetraethylborate (NaBEt4). Nine organotin compounds were extracted from samples with acetone-hexane and derivatized with NaBEt4. The derivatives were then analyzed by GC/MS. The method was applied to samples of polyvinyl chloride food containers, gloves, spouts, hoses and pipes. Recoveries from spiked samples ranged from 49.1-118.1%. Various organotin compounds were detected in the plastic products tested.