AbstractThe determination of tributyltin (TBT) in sea food (mussel, oyster, fish) by a hydride generation–cold trapping–quartz furnace atomic absorption spectrometry procedure has been studied with emphasis on quality control. Large amounts of spiked materials have been prepared and stored either frozen, or frozen after freeze‐drying. Extraction of TBT by 0.1Mhydrochloric acid in methanolic solution is efficient (88–96%) for wet samples or freeze‐dried samples. It is also efficient with freshly spiked materials. Consumption of sodium borohydride by the matrix makes it necessary to use quite large amounts of reagent to obtain optimal sensitivity. Analysis of a fish‐tissue Certified Reference Material seems to indicate a partial debutylation of TBT during transport and/or storage of th