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本文用硝酸—氢氟酸分解硅铝合金,在室温下,极为迅速地(30秒)将试样分解完全,用硼酸络合氟离子,在草酸的掩蔽下,以偶氮氯膦—mA(CPA-mA)为显色剂,直接光度法测定铝合金中的稀土总量,方法操作简便、快速准确、重现性好。 步骤:称取试样0.1000g置于塑料杯中,加3ml(1+1)HNO_3和2ml HF,摇动溶解后,加95ml 3%硼酸溶液,充分摇匀,吸取试液2ml于预先置有20ml混合显色剂(取CPA-mA0.07g,草酸40g,用水稀释至1升,摇匀)的50ml容量瓶中,以水稀释至刻度,摇匀,在72型分光光度计上,于660nm处,2cm比色皿,以纯铝(或不含稀土的铝合金)按同样操作为参比液,测定吸光度。
In this paper, nitric acid - hydrofluoric acid decomposition of silicon aluminum alloy, at room temperature, very quickly (30 seconds) will be the sample completely decomposed, with boric acid complex fluoride, oxalic acid masking, chlorophosphonazo-mA CPA-mA) as chromogenic agent, direct determination of the total amount of rare earth aluminum alloy, the method is simple, fast and accurate, reproducible. Step: Weigh the sample 0.1000g placed in a plastic cup, add 3ml (1 + 1) HNO_3 and 2ml HF, shake to dissolve, add 95ml 3% boric acid solution, shake well, aspirate 2ml test solution pre-set with 20ml Mixed color reagent (take CPA-mA0.07g, oxalic acid 40g, diluted with water to 1 liter, shake) in 50ml volumetric flask, diluted with water to the mark, shake, on a Model 72 spectrophotometer at 660nm , 2cm cuvette, pure aluminum (or rare earth-free aluminum alloy) according to the same operation as a reference solution, measured absorbance.