Rapid, accurate and precise determination of tributyltin in sediments and biological samples by species specific isotope dilution-microwave extraction-gas chromatography-ICP mass spectrometry

The rapid and precise determination of tributyltin (TBT) in sediments and biological tissues has been performed by species specific isotope dilution mass spectrometric analysis (IDMS) using an inductively coupled plasma mass spectrometer as detector after capillary gas chromatography (CGC-ICP-MS). A new labelled TBT standard ((TBTCl)-T-117 in methanolic solution) commercial isotope provided by LGC Limited (Teddington, UK) was used for these determinations. Parameters affecting the ICP-MS performances, such as correction for detector dead time and mass bias correction, were carefully studied. The mass bias was corrected using two different methods: the bracketing mode and an on-line mode based on a continuous nebulisation of an antimony solution (Sb-121 and Sb-123). The on-line mode has been successfully applied for mass bias corrections and allows simultaneous GC-ICP-MS analysis of organotins. Three spiking procedures were compared using isotopically enriched TBT ((TBT)-T-117) to compare the efficiency of the extraction procedures for the different samples studied. A rapid method was developed (2 min) giving yield to good precision (uncertainty range between 0.7 and 13.7%) using a simultaneous microwave extraction and spiking procedure. The accuracy and precision of the different protocols has been validated on certified reference materials, such as PACS 2 (980 ng Sn g(-1)) and CRM 462 (70 ng Sn g(-1)) for the sediments, CRM 477 (2200 ng TBT g(-1)) and CRM 710 (135.1 ng TBT g(-1)) for the biological tissues. The results obtained were in all cases in good agreement with the certified reference values.