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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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This survey determined the levels of eight phthalates - i.e. dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), benzylbutyl phthalate (BzBP), di(2-ethylhexyl) phthalate (DEHP), dicyclohexyl phthalate (DCHP) and di-n-octyl phthalate (DnOP) - in several Belgian milk and dairy products. Samples were obtained from various farms, a dairy factory and from different shops in order to investigate phthalate contamination "from farm to fork". At several stages in the milk chain, product contamination with phthalates - mostly DiBP, DnBP, BzBP and DEHP - was observed. At farm level, the mechanical milking process and the intake of phthalate containing feed by the cattle were found to be possible contamination sources. At industry and retail level, contact materials including packaging materials were additional contamination sources for phthalates in milk and dairy products.

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The performance of a commercially available microconcentric nebulizer (MCN-100, CETAC Technologies, USA) operated at flow rates ranging from dO.001 up to 0.65 ml min-' was evaluated using a Perkin-Elmer Sciex ELAN 5000 ICP-mass spectrometer. The observations made were compared with those for the standard GemTip cross-flow nebulizer. Registration of signal behaviour plots (signal intensity as a function of the nebulizer gas flow rate) at different rf powers and at different sample uptake rates allowed firstly, a systematic optimization of the operation parameters, and secondly, a comparison of the signal behaviour observed when using both types of nebulizer. The stability of the MCN-100 was evaluated at different sample uptake rates and the Occurrence of memory effects was checked for a number of elements. Also, the level and the behaviour of oxide and doubly charged ions was studied. Furthermore, the susceptibility to matrix effects was investigated using synthetic matrices of different origin (acid, organic and high salt content) and it was demonstrated that, generally, matrix effects observed with both nebulizers are comparable and the MCN-100 can be used with NaCl concentrations up to 4 g I-' without capillary blocking. Finally, it is illustrated that the MCN-100 can be applied at sample flow rates of < 5 p1 min-', as are encountered when coupling capillary zone electrophoresis to ICP-MS for elemental speciation studies.