Certification of the methylmercury content in SRM 2977 mussel tissue (organic contaminants and trace elements) and SRM 1566b oyster tissue.

The methylmercury content in two new marine bivalve mollusk tissue Standard Reference Materials (SRMs) has been certified using results of analyses from the National Institute of Standards and Technology (NIST) and two other laboratories. The certified concentrations of methylmercury were established based on the results from four and six different (independent) analytical methods, respectively, for SRM 1566b Oyster Tissue (13.2 +/- 0.7 microg/kg) and SRM 2977 Mussel Tissue (organic contaminants and trace elements) (36.2 +/- 1.7 microg/kg). The certified concentration of methylmercury in SRM 1566b is among the lowest in any certified reference material (CRM).

Preconcentration and determination of Sn- and Pb-organic species in environmental samples by SPME and GC-AED.

A new sample preparation and preconcentration technique - solid phase microextraction (SPME) - is reported for the application of several tinorganic compounds and tetrabutyllead in aqueous samples. The solvent-free procedure is rapid in comparison with liquid-liquid extraction or SFE but also sensitive. Analytical variables of the extraction such as adsorption and desorption time, stirring rate and temperature has been investigated. The determination has been performed by GC coupled with atomic emission detection (AED). After optimization of the conditions of SPME a calibration was realized on the basis of a multicomponent standard solution, prepared by ethylation of organotin salts directly in the sample using sodium tetraethylborate (NaBEt(4)) without prior separation of the analytes from the matrix. The method permits preconcentration. Values of about 10 can be reached. A detection limit of 0.09 pg Sn and 0.08 pg Pb can be achieved under optimized conditions. The proposed procedure has been successfully applied to the analysis of organotin compounds in various slurry samples.