DETERMINATION OF OTCs IN MARINE SEDIMENTS: ANALYTICAL METHODS AND ENVIRONMENTAL CONCERNS

During the last century, organotin compounds (OTCs) have been widely used as accelerators, polyvinyl chloride (PVC) stabilizers, biocides, coatings, wood preservatives and antifouling paints. As consequence tributyltin compounds occur at high concentrations in water, sediment, and biota associated with harbour locations whereas dibutyltin and monobutyltin contamination is believed to result from tributyltin degradation rather than from direct input. TBT can cause chronic and acute toxic effects to algae, zooplankton, mollusks, and some fish species even at very low concentrations. TPhT is less toxic than TBT, but can also be of high risk to aquatic life. The persistence and fate of organotins in the aquatic environment are functions of such factors as aqueous solubility and vapour pressure of the compound, adsorption to suspended matter and sediments, and abiotic and biotic methylation and demethylation. To evaluate the environmental distribution and fate of these compounds and to determine the efficiency of legal provisions adopted by a number of countries, a variety of analytical methods have been developed for organotin determination in the environment. Many laboratories in the world are analyzing samples and revealing the continuous input of TBT in many environmental matrices, especially marine sediments. The determination of OTCs in environmental matrices has been subject of great scientific attention during the latest years, as the accuracy and sensitivity of analytical methods need to be improved in order to be able to detect the compounds of interest in a complex matrix such as sediments. Therefore, significant research is being devoted to the optimization of analytical methodologies. A great number of studies have been performed on OTCs analysis in marine sediments. However the only review available in literature discussing the upgrading of analytical methods is dated 1997. So far various analytical procedures have been used, including gas chromatographic analyses. Most of these methods include different steps such as extraction, derivatisation, clean up and the use of several sophisticated instrumentations, as well. Therefore the conversion of TBT into Sn to allow its determination by metal determination techniques such as Atomic Absorption Spectrometry or Anodic Stripping Voltammetry (AVS) has also been attempted. These procedures are reviewed and comparatively discussed in this paper in order to identify the more suitable and environmentally-friendly alternatives.