Optimization and validation by SPE-CGC-MSD of the analysis of tributyltin in environmental samples

The optimization by SPE-CGC-MSD methodology of the analysis of tributyltin in environmental samples is presented. Fifteen assays with certified reference material for sediment matrices (54±15 ng/g), as well as with in-house standards for aqueous matrices (50 ng), were performed using solid phase extraction for tributyltin speciation, which was shown to be easy, solventless, and fast. The solid phase extraction tube was preconditioned with ethyl acetate to remove possible impurities, conditioned with methanol, water, and HCl 5% and after tributyltin extraction, washed again with HCl 5% and water, and finally eluted with ethyl acetate. Subsequently the samples were derivatized with methyl magnesium bromide in a diethylether solution, concentrated, injected in the splitless mode, separated by capillary gas chromatography, and detected by mass spectrometry in the selected ion-monitoring mode. The results obtained showed a value of 50±18 ng/g for tributyltin in the sediment matrices assays which, according to European Co-operation for Accreditation of Laboratories guidance for interlaboratory comparisons, led to a deviation normalized lower than 0.2, showing that the SPE-CGC-MSD methodology is validated for TBT speciation in sediment samples, due to the high accuracy reached. For the in-house standard aqueous matrices assays, a value of 44±21 ng gave recoveries higher than 85%, showing that this methodology is also validated, due to the substantial accuracy for tributyltin speciation in aqueous samples. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 48–53, 2001