Application of experimental design in a method for screening sediments for global determination of organic tin by electrothermal atomic absorption spectrometry (ETAAS).

An experimental design was developed to obtain a simple procedure for global determination of organic tin compounds in sediment. Sediment was extracted by a two-phase method and tin was determined in the organic extract by electrothermal atomic absorption spectrometry (ETAAS), with palladium as chemical modifier. A Plackett-Burman design for screening and a fractional central composite design (CCD) for optimizing were used for evaluation of the effects of several variables. The results showed that sediment mass, volume and concentration of extracting acid, pyrolysis and atomization temperatures, and modifier concentration affect the determination. Reference material PACS-2 was analyzed to evaluate the procedure. It was possible to extract 82% of the organotin content certified in the reference sediment. The limit of detection (LOD) was 0.08 microg g(-1) and the relative standard deviation was 4%. The method was applied to the analysis of estuarine superficial sediments from Gipuzkoa (Spain). The organotin content of these samples ranged from 0.7 to 7.7 microg g(-1), as tin, on a dry-weight basis.