Simultaneous determination of arsenic and selenium in geochemical samples by hydride evolution and atomic-absorption spectrometry: success and failure
An assessment is made of the simultaneous determination of arsenic and selenium in geological materials by hydride generation and two atomic-absorption spectrometric techniques. In one the hydride(s) are absorbed into silver nitrate solution and aliquots injected into a graphite furnace. In the other the hydrides are directly atomised in a heated quartz cell. Data are presented for USGS geochemical reference materials GXR 1–6. The samples are decomposed in nitric-perchloric acid, taken to incipient dryness and the residues extracted with hydrochloric acid. Zinc shot or sodium tetrahydroborate are used as reductants to produce the hydrides. Simultaneous determinations can be made, using the latter, provided the arsenic to selenium ratio is favourable.