A simple chromatographic method was developed for the simultaneous determination of butyl- and octyltin compounds in two aqueous-based food simulants, water and 3% (w/v) acetic acid. The procedure is based on one-step derivatization/extraction with sodium tetraethylborate directly in the aqueous phase in the presence of 1 ml of 0.05% (w/v) tropolone in hexane. Derivatization parameters such as extraction solvent, pH, reaction time and amount of the reagent were optimized. The corresponding ethylated compounds were analysed by GC-MS using tripropyltin (TPrT) and diheptyltin (DHT) as internal standards for butyl- and octyltin compounds, respectively. This new method was validated and evaluated for linearity, trueness and precision in both simulants. The detection limits were in the range 1.9 (MBT) to 8.8 (TBT) µg l−1 (as organic–metallic cation) in both simulants. The stability of the organotin compounds under migration conditions (10 days at 40 °C) was also tested. The tested organotins presented no significant losses under the migration conditions. The developed method was applied to some PVC food packaging materials from the market. Few organotins were detected at levels near the limit of quantitation. Copyright © 2007 John Wiley & Sons, Ltd.