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称0.1～0.3g试样,以少许水湿润,加入15ml硝酸—氯酸钾饱和溶液,待剧烈作用停止后,加热溶解,并蒸至2～3ml,冷却,以水稀至100ml,加热溶解盐类。冷却,以氨水中和至氢氧化铁沉淀开始析出,再以1:1硝酸滴至沉淀刚消失,调节pH1～2。加入几滴0.5%磺基水杨酸指示剂,以0.05M-EDTA滴至黄色终点(按EDTA毫升数计算铁含量)。将溶液调节pH=2～4,煮沸,加20%硝酸铅5～10ml,搅拌,再煮沸1～2分钟。取下,加入20ml乙醇,流水冷却至室温。以慢速滤纸过滤,以硝酸酸
Weigh 0.1 ~ 0.3g sample, moist with a little water, add 15ml saturated solution of nitric acid - potassium chlorate, to stop the violent action, heated to dissolve and steam to 2 ~ 3ml, cooled to dilute with water to 100ml, heated to dissolve salts. Cooling, to ammonia and iron hydroxide precipitation precipitation, and then 1: 1 nitric acid drops to the precipitate just disappeared, adjust pH1 ~ 2. Add a few drops of 0.5% sulphosalicylic acid indicator and drop to 0.05% final yellow (calculated as iron content in milliliters of EDTA) with 0.05M-EDTA. The solution was adjusted to pH 2 ~ 4, boiled, add 20% lead nitrate 5 ~ 10ml, stirring, and then boil for 1 to 2 minutes. Remove, add 20ml of ethanol, water cooled to room temperature. Slow filter paper to nitric acid