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 dilution to volume and degassing the samples upon addition of urea.
The selenium is converted to the +4 oxidation state during digestion in HCl.
After a 1:10 dilution, selenium is then converted to its volatile hydride 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 absorption cell located in the optical path of an atomic absorption
spectrophotometer. The resulting absorption of the lamp radiation is
proportional to the selenium concentration.
2.3 The typical detection limit for this method is 3 µg/L.详细>