CRITICAL CONSIDERATIONS WITH RESPECT TO THE IDENTIFICATION OF TIN SPECIES IN THE ENVIRONMENT

Biogeochemical pathways of tin species in the environment are still co ntroversial, e.g. with regard to methylation and transmethylation phen omena, owing to the fact that the identification of methylated tin-com pounds is often difficult. The previous tentative identification of a mixed methylbutyltin compound in sediment and biological samples by GC /AAS after hydride generation gave an illustration of this problem. Th is compound was previously identified in sediments by other authors an d also suspected to occur in a contaminated sediment sample from the B oyardville Marina, France. The retention time obtained by GC/AAS corre sponded to the actual retention time of a mixed methylbutyltin calibra nt. However, additional checks demonstrated that the compound detected was actually monophenyltin. This evidence was produced by a thorough analysis of a selected sediment sample by alternative techniques such as GC/AAS and GC/AES after pentylation, GC/FPD and GC/MS. The results presented highlight the need for a full identification of compounds to avoid mis-interpretation.