简介:2.1 Samples are prepared according to the nitric acid digestion procedure
described in Method 3010 for aqueous and extract samples and the
nitric/peroxide/hydrochloric acid digestion procedure described in Method 3050
简介:2.1 Samples are prepared according to the nitric acid digestion procedure
described in Method 3010 for aqueous and extract samples and the
nitric/peroxide/hydrochloric acid digestion procedure described in Method 3050
(furnace AA option) for sediments, soils, and sludges. Excess peroxide is
removed by evaporating samples to near dryness at the end of the digestion
followed by degassing the samples upon addition of urea. L-cysteine is then
added as a masking agent. Next, the antimony and arsenic in the digest are
reduced to the trivalent forms with potassium iodide. The trivalent antimony and
arsenic are then converted to volatile hydrides using hydrogen produced from the
reaction of the acidified sample with sodium borohydride in a continuous-flow
hydride generator.
2.2 The volatile hydrides are swept into, and decompose in, a heated
quartz cell located in the optical path of an atomic absorption
spectrophotometer. The resulting absorption of the lamp radiation is
proportional to the arsenic or antimony concentration.详细>