The use of the solid phase microextraction (SPME) technique for the simultaneous determination of organomercury, -tin, and -lead is described. The organometallic compounds were in situ derivatized with sodium tetraethylborate, sorbed on a poly(dimethylsiloxane)-coated fused silica fiber, and desorbed in the splitless injection port of the GC. The different organometallic compounds were simultaneously determined by an inductively coupled plasma mass spectrometer (ICPMS) coupled to the GC using a transfer line developed in-house. The detection limits obtained with CGC−ICPMS for monobutyl-, dibutyl-, and tributyltin are between 0.34 and 2.1 ng/L as Sn. Analysis of a PACS-1 reference material confirmed the reliability of the combination of SPME as extraction technique with CGC−ICPMS for the analysis of organotin compounds.

ICP mass spectrometry is being increasingly used for isotopic analysis and for element determination by means of isotope dilution. For accurate isotope ratio determination, both the mass discrimination and the detector dead time have to be appropriately corrected for. For a Finnigan-MAT Element and a Perkin-Elmer SCIEX Elan 5000 ICP mass spectrometer, the constancy of the detector dead time across the mass range was systematically investigated. For the Element, which is equipped with a conversion dynode and a secondary electron multiplier with discrete dynodes, the dead time was observed to be independent of the analyte mass number. For the Elan 5000, however, which is equipped with a Channeltron-continuous dynode-electron multiplier, the detector dead time was observed to be strongly mass-dependent. The decreasing gain of Channeltron electron multipliers with increasing ion mass may be at the origin of the behaviour established. This observation has to be taken into account when highly accurate isotope ratio measurements are required and hence the detector dead time has to be properly determined and corrected for

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Capillary electrophoresis (CE) was used to separate four anionic {arsenite [As()], arsenate [As()], monomethylarsonic acid and dimethylarsinic acid } and two cationic forms (arsenobetaine and arsenocholine) of As in a single run. At sufficiently high concentrations, the determination of these compounds could be accomplished by means of UV detection. The determination of low concentrations (<10 mg l−1) of these compounds of interest was accomplished by coupling CE on-line with inductively coupled plasma mass spectrometry (ICP-MS ). To accomplish this coupling, a microconcentric nebulizer was used. The modifications necessary to make a conventional CE system compatible with ICP-MS, the optimization of the operation parameters and of sample stacking conditions together with the effect of the sheath liquid and of an induced laminar flow are discussed. The analytical figures of merit of the method were assessed and the limit of determination (based on the peak height of a peak for which the signal-to-noise ratio is 1051) was found to be 1-2 mg l−1 As for each species. The recovery for the compounds of interest was determined using a spiked mineral water sample. Samples of mineral water, soil leachate and urine were analyzed with the CE-ICP-MS combination. plasma. Furthermore, since concentric nebulizers are self-

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