Determination of arsenic species in sea-water by hydride generation atomic fluorescence spectroscopy

A method for the determination of arsenate, arsenite, monoethylarsonate and dimethylarsinate was developed using hydride generation and cold trapping of the hydrides, coupled with atomic fluorescence detection at 193.7 nm. Optimisation of the signal was carried out for a number of experimental parameters including the carrier gas how rates, sample volume and the concentration and addition time of NaBH4. The detection limits for As-III, As-V, MMA and DMA are 2.3, 0.9, 2.4 and 3.7 ng l(-1), respectively, in a 5 mi sample. The precision for nine sample replicates was better than 3.5% for all the arsenic species. The accuracy of the method was determined by analysis of a seawater reference material (NASS-4) and by recovery studies on natural samples; Examples of the method's application to the analysis of arsenic species in unpolluted coastal sea-water are given.