Phenyl- and butyltin analysis in small biological samples by cold methanolic digestion and GC/MS

A very efficient technique for the analysis of six butyl- and phenyltin compounds in biota samples has been developed. No special equipment is needed for sample preparation, which is based on cold methanolic digestion with subsequent aqueous ethylation and liquid-liquid extraction. For samples of only 40 mg of biological materials, method detection limits ranging from 4 to 52 ng/g were achieved using gas chromatography/mass spectrometry. Relative recoveries for the individual butyl- and phenyltins, referring to perdeuterated organotin analogues as internal standards, ranged from 96 to 107%. Organotin concentrations in insect larvae (Chironomus riparius) and a reference mussel tissue (CRM 477) were determined with excellent precision (RSD <5%), and the measured butyltins in CRM 477 were in good agreement with the certified values. Comparison with accelerated solvent extraction confirmed high accuracy, and application for a bioconcentration experiment with phenyltins demonstrated the robustness and suitability of the method for routine analyses. The procedure allows fast, reliable, and simple determination of organotin compounds in low-size biological samples, which was demonstrated for bioconcentration experiments.