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称取试样5克置于600毫升高型烧杯中,加浓盐酸50毫升及少量水,加热溶解,加浓硝酸5毫升,煮沸,稍冷,加硫酸(1+1)20毫升,蒸发到冒浓白烟,维持5分钟。冷却,小心加水50毫升,煮沸溶解盐类,冷却后加入50毫升乙醇,静置过夜。过滤,用硫酸(1+9)洗涤6～8次(洗至无铁离子),滤液弃去。用煮沸之乙酸铵(20%)80毫升反复溶解沉淀,最后用热水洗涤6～8次。溶液及洗液置400毫升烧杯中,以水稀释至200毫升。煮沸,加重铬酸钾(10%)20毫升,加热至近沸,并保持约30分钟。取下放置1小时,于预经110℃恒重之G3玻璃过滤坩埚中进行抽滤,用稀乙酸溶液(1%)洗涤至无重铬酸钾之黄色,再
Weigh 5 grams of the sample was placed in 600 ml high-type beaker, add concentrated hydrochloric acid 50 ml and a small amount of water, dissolved by heating, add concentrated nitric acid 5 ml, boil, slightly cold, add sulfuric acid (1 +1) Take thick white smoke for 5 minutes. Cool, carefully add water 50 ml, boil dissolved salt, add 50 ml of ethanol after cooling, allowed to stand overnight. Filtered, washed with sulfuric acid (1 +9) 6 to 8 times (washed until no iron ions), the filtrate was discarded. With boiled ammonium acetate (20%) 80 ml repeatedly dissolved precipitate, and finally washed with hot water 6 to 8 times. Solution and lotion 400 ml beaker, diluted with water to 200 ml. Boil, add 20 ml potassium chromate (10%), heat to near boiling and hold for about 30 minutes. Take it aside for 1 hour and filter by suction in a G3 glass filter crucible pre-conditioned at 110 ° C. Wash with dilute acetic acid solution (1%) to a yellow color without potassium dichromate.