Determination of Tributyltin (TBT) in Marine Sediment using Pressurised Liquid Extraction - Gas Chromatography - Isotope Dilution Mass Spectrometry (PLE-GC-IDMS): Method Development

Abstract

An analytical procedure including isotope dilution calibration for the determination of tributyltin (TBT) in sediment samples has been developed. The procedure is based on spiking with isotopically labelled analyte, pressurised liquid extraction (PLE), followed by Grignard-derivatisation and quantification by GC-MS. The method was applied on two unknown sediment samples as a part of an intercomparison exercise organised by the National Research Council of Canada (NRCC) and LGC (UK) on behalf of the Comité Consultatif pour la Quantité de Matière (CCQM). The value found was 103.6 % ± 3.1 % of the certified value by use of the reference material PACS-2, and the detection limit was estimated to be approximately 1.5 ng/g of sediment as Sn. Repeatability and intermediate precision were calculated as coefficient of variation and their values were 1.9 % and 3.2 % respectively. The expanded uncertainty was calculated according to GUM [], and was 6.2 % (coverage factor k=2) and the final values agree with the certified values within their respective uncertainties.