Determination of Methyltin and Butyltin Compounds in Environmental Water and Sediment Samples

Abstract

Although today most techniques for the determination of organotin compounds provide adequate precision, problems concerning the accuracy of data obtained from actual environmental samples still exist. Two important sources of error are the storage of samples and the extraction of organotin compounds from environmental matrices. The stability of methyl- and butyltin compounds in freshwater samples stored in polycarbonate containers was examined: storage at + 10°C and freezing at − 20°C both conserved original concentrations for some days, but resulted in losses after prolonged storage. For sediment samples, freeze-drying was found to be a reliable method of conservation. Extraction efficiency was evaluated for the extraction of sediment samples by refluxing in methanol/hydrochloric acid. Spiking and re-extracting a sediment may result in an overestimate of extraction efficiency. More accurate data can be obtained by using a method based on extracting sediment with varying volumes of solvent. Our data suggest that tin speciation, as well as the type of sediment, influence extraction efficiency significantly.