Donaldson E M
Mineral Sciences Laboratories, Canada Centre for Mineral and Energy Technology, Department of Energy, Mines and Resources, Ottawa, Canada.
Talanta. 1988 Aug;35(8):633-9. doi: 10.1016/0039-9140(88)80145-0.
A method for determining approximately 0.01 mug/g or more of selenium in ores, concentrates, rocks, soils, sediments and related materials is described. After sample decomposition selenium is reduced to selenium(IV) by heating in 4M hydrochloric acid and separated from the matrix elements by toluene extraction of its 5-nitropiazselenol complex from approximately 4.2M hydrochloric acid. After the extract has been washed with 2% nitric acid to remove residual iron, copper and chloride, the selenium in the extract is oxidized to selenium(VI) with 20% bromine solution in cyclohexane and stripped into water. This solution is evaporated to dryness in the presence of nickel, and selenium is ultimately determined in a 2% v/v nitric acid medium by graphite-furnace atomic-absorption spectrometry at 196.0 nm with the nickel functioning as matrix modifier. Common ions, including large amounts of iron, copper and lead, do not interfere. More than 1 mg of vanadium(V) and 0.25 mg each of platinum(IV), palladium(II), and gold(III) causes high results for selenium, and more than 1 mg of tungsten(VI) and 2 mg of molybdenum(VI) causes low results. Interference from chromium(VI) is eliminated by reducing it to chromium(III) with hydroxylamine hydrochloride before the formation of the selenium complex.
描述了一种测定矿石、精矿、岩石、土壤、沉积物及相关物料中约0.01μg/g或更高含量硒的方法。样品分解后，通过在4M盐酸中加热将硒还原为硒（IV），并通过从约4.2M盐酸中用甲苯萃取其5-硝基苯并硒酚络合物，使其与基体元素分离。萃取液用2%硝酸洗涤以除去残留的铁、铜和氯后，萃取液中的硒用环己烷中的20%溴溶液氧化为硒（VI），并反萃取到水中。该溶液在镍存在下蒸发至干，最终在2% v/v硝酸介质中，通过石墨炉原子吸收光谱法在196.0nm处测定硒，镍作为基体改进剂。常见离子，包括大量的铁、铜和铅，不产生干扰。超过1mg的钒（V）以及各0.25mg的铂（IV）、钯（II）和金（III）会导致硒的测定结果偏高，超过1mg的钨（VI）和2mg的钼（VI）会导致测定结果偏低。在形成硒络合物之前，用盐酸羟胺将铬（VI）还原为铬（III），可消除铬（VI）的干扰。
