Field cryofocussing hydride generation applied to the simultaneous multi-elemental determination of alkyl-metal(loid) species in natural waters usingICP-MS detection

Two hydride generation manifold systems, utilizing flow injection and cryot rapping techniques for alkyl-metal(loid) speciation analysis in natural wat ers, are described in this paper. They provide shipboard capacity for simul taneous derivatization of analytes with NaBH4 and cryotrapping of the gener ated products in a field packed column at -196 degreesC. The first system i s a large-volume hydride generator, using a reagent-injection flow techniqu e as a flow batch type, that has been fully optimized and applied to the si multaneous detection of alkylated species in estuarine waters. The techniqu e permits the analysis of a large volume sample (0.5-11) at a sampling rate of 3 h(-1). The second is an online continuous flow hydride generator. A s ampling rate of 3-12 h(-1) can be achieved with samples of 0.1-0.5 l. In ad dition, shipboard operation eliminates major problems related to sample pre treatment, transport and storage. Ultra-trace multi-element determination i s finally performed in the laboratory by cryogenic GC hyphenated with ICP-M S. Routine detection limits of 0.5-10 pg (as metal) for 0.5 l water samples were achieved for the selected alkyl-metal(loid) species of arsenic, germa nium, mercury and tin. Concentrations of various species, obtained from wat er samples taken from the Rhine estuary, are also presented. These species include alkylated arsenic compounds, other than methyl derivatives, that ha ve been tentatively identified and are reported here for the first time.