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分析手续:称取0.2克试样,加硫磷混合酸(每升中含硫磷酸各200毫升)25毫升,加热溶解,滴加硝酸破坏碳化物,蒸至发烟。稍冷,加高氯酸10毫升,继续加热冒烟,待溶液转为桔红色后,于低温电炉上保持1～2分钟。冷却,加水50毫升,冷却,以0.05N硫酸亚铁铵标准溶液滴定至浅黄色,加0.5%二苯胺磺酸钠指示剂2滴,继续滴定至溶液由紫红转为亮绿色为终点,V_1(铬锰钒总量)。
Analysis procedures: Weigh 0.2 g sample, add phosphoric acid and phosphoric acid (each containing 200 ml of phosphorothioate) 25 ml, dissolved by heating, dropping nitric acid to destroy carbides, steaming to smoke. Slightly cold, add perchloric acid 10 ml, continue heating and smoking, until the solution turns orange, the low temperature electric furnace to maintain 1 to 2 minutes. Cooling, add water 50 ml, cooled to 0.05N ammonium ferrous sulfate standard solution titration to light yellow, add 0.5% sodium diphenylamine sulfonate indicator 2 drops, continue titration until the solution turns from purple to bright green as the end, V_1 ( Chrome manganese vanadium total).