Speciation of butyl- and phenyltin compounds in sediments using pressurized liquid extraction and liquid chromatography-inductively coupled plasma mass spectrometry

A liquid chromatographic method with inductively coupled plasma mass spectr ometry is proposed for the speciation of butyl- (monobutyltin, dibutyltin, tributyltin) and phenyl- (monophenyltin, diphenyltin, triphenyltin) tin com pounds in sediments. After evaluation of different additives in the mobile phase. the use of 0.075% (w/v) of tropolone and 0.1% (v/v) of triethylamine in a mobile phase of methanol-acetic acid-water (72.5:6:21.5) allowed the best chromatographic separation of the six compounds. Pressurized liquid ex traction (PLE) with a methanolic mixture of 0.5 M acetic acid and 0.2% (w/v ) of tropolone was suitable for the quantitative extraction of butyl- and p henyltin compounds with recovery values ranging from 72 to 102%. This analy tical approach was compared to conventional solvent extraction methods maki ng use of acids and/or organic solvent of medium polarity. The main advanta ges of PLE over conventional solvent extraction are: (i) the possibility to extract quantitatively DPhT and MPhT from sediments, which could not be do ne by a solvent extraction approach; (ii) to preserve the structural integr ity of the organotin compounds; (iii) to reduce the extraction time from se veral hours in case of solvent extraction techniques to just 30 min. For sp iked sediments, limits of detection ranged from 0.7 to 2 ng/g of tin accord ing to the compound. The relative standard deviations were found to be betw een 8 and 15%. The developed analytical procedure was validated using a ref erence material and was applied to various environmental samples. (C) 2000 Elsevier Science B.V. All rights reserved.