A simple method for synthesis of organotin species to investigate extraction procedures in sediments by isotope dilution gas chromatography-inductively coupled plasma mass spectrometry Part 1. Butyltin species

Abstract

A method for the synthesis of butyltin species, based on the butylation of tin iodide in diethyl ether, was developed. A standard of ¹¹⁶Sn enriched monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TeBT) was produced and used as a spike for isotope dilution gas chromatography-inductively coupled plasma mass spectrometry. Isotope enriched species were added to and equilibrated with certified reference sediments NRC PACS-2 and BCR 646 to evaluate different extraction procedures currently used for the determination of butyltins in sediments. Measurement results agreed with certified values for TBT, DBT and MBT for the certified reference materials, using extraction methods with acetic acid–methanol or 50% HBr. Poorer results were obtained for extractions using the complexing agent tropolone in diethylether or a methanol/dichloromethane mixture, or with sequential extractions including tropolone in diethyl ether and NaCl in hydrochloric acid. The TeBT spike was used to investigate the extraction efficiencies of the species. For the method involving 50% HBr the extraction efficiencies were found to be 102% for TBT, 85% for DBT and 27% for MBT. Although the calculated efficiencies were low for MBT, when extracting with 50% HBr recoveries of 97% for BCR 646 and 110% for PACS-2 were obtained with species-specific isotope dilution calibration.