Simultaneous co-extraction of organometallic species of different elements by accelerated solvent extraction and analysis by inductively coupled plasma mass spectrometry coupled to liquid and gas chromatography.

Abstract

This paper describes the development of an accelerated solvent extraction methodology that is capable of simultaneously extracting organometallic species of As, Sn and Hg in a semi-automated manner. Accelerated solvent extraction (ASE) methods based on previous research on the separate extraction of organotin and -arsenic species in our laboratory were adapted for the co-extraction of six different species from an oyster tissue certified reference material (BCR 710). For the first time, the extraction of MeHg by this technique is also investigated. The proposed ASE conditions employed 50% acetic acid in methanol at a temperature of 100 degrees C with up to five consecutive extraction cycles of 3 minutes. Extraction efficiencies for organoarsenic species ranged from 80% (dimethylarsinic acid, DMA) to 99% for arsenobetaine (AsB). Species of toxicological interest, such as dibutyltin (DBT), tributyltin (TBT) and methylmercury (MeHg), were extracted with mean recoveries of 81, 84 and 76%, respectively. The extracted species were analysed by gas chromatography/inductively coupled plasma mass spectrometry (GC/ICPMS; DBT, TBT and MeHg) and liquid chromatography/inductively coupled plasma mass spectrometry (LC/ICPMS; MMA, DMA, AsB) after ethylation with sodium tetraethylborate or dilution with water, respectively. In addition to those species for which the extraction efficiency was assessed during this study, a further five arsenic species (arsenite, arsenate and three unidentified species), as well as monobutyltin (MBT) and mono-, di- and triphenyltin, could also be extracted from other matrices. The developed ASE method provides a significant improvement over many currently available routine monitoring methods for trace element speciation due to the fact that it is capable of extracting several species of toxicological interest simultaneously and quantitatively.