Donaldson E M, Leaver M E
Mineral Sciences Laboratories, Canada Centre for Mineral and Energy Technology, Department of Energy, Mines and Resources, Ottawa, Canada.
Talanta. 1988 Apr;35(4):297-300. doi: 10.1016/0039-9140(88)80089-4.
A recent graphite-furnace atomic-absorption method for determining approximately 0.2 mug/g or more of arsenic in ores, concentrates, rocks, soils and sediments, after separation from matrix elements by cyclohexane extraction of arsenic(III) xanthate from approximately 8-10M hydrochloric acid, has been modified to include an alternative hydride-generation atomic-absorption finish. After the extract has been washed with 10M hydrochloric acid-2% thiourea solution to remove co-extracted copper and residual iron, arsenic(III) in the extract is oxidized to arsenic(V) with bromine solution in carbon tetrachloride and stripped into water. Following the removal of bromine by evaporation of the solution, arsenic is reduced to arsenic(III) with potassium iodide in approximately 4M hydrochloric acid and ultimately determined to hydride-generation atomic-absorption spectrometry at 193.7 nm, with sodium borohydride as reductant. Interference from gold, platinum and palladium, which are partly co-extracted as xanthates under the proposed conditions, is eliminated by complexing them with thiosemicarbazide before the iodide reduction step. The detection limits for ores and related materials is approximately 0.1 mug of arsenic per g. Results obtained by this method are compared with those obtained previously by the graphite-furnace method.
最近一种石墨炉原子吸收法，用于测定矿石、精矿、岩石、土壤和沉积物中约0.2μg/g或更多的砷。该方法是在约8 - 10M盐酸中，通过环己烷萃取砷(III)黄原酸盐从基体元素中分离出砷后进行测定的，现进行了改进，采用了一种替代的氢化物发生原子吸收法作为最终测定方法。在用10M盐酸 - 2%硫脲溶液洗涤萃取液以除去共萃取的铜和残留的铁之后，萃取液中的砷(III)用四氯化碳中的溴溶液氧化为砷(V)，然后反萃取到水中。通过蒸发溶液除去溴之后，在约4M盐酸中用碘化钾将砷还原为砷(III)，最终用硼氢化钠作为还原剂，在193.7nm处通过氢化物发生原子吸收光谱法进行测定。在所提出的条件下，金、铂和钯会部分以黄原酸盐形式共萃取，在碘化物还原步骤之前，通过用氨基硫脲络合它们来消除其干扰。矿石及相关物料的检测限约为每克0.1μg砷。将该方法获得的结果与先前用石墨炉法获得的结果进行了比较。
