丙酮氰醇对铜(Ⅱ)、锌(Ⅱ)、镍(Ⅱ)、镉(Ⅱ)、铁(Ⅱ)等离子的掩蔽作用与氰化钾相似,而毒性远比氰化钾小。为此,笔者通过实验拟订了以抗坏血酸、酒石酸、三乙醇胺、丙酮氰醇及EDTA联合掩蔽干扰离子,用甲醛解蔽,5-Br-PADAP-OP作指示剂以EDTA标准溶液滴定含锰铜合金中锌的方法。方法终点敏锐,重现性好。主要试剂EDTA标准溶液:0.01M和0.02M,用含锌量已知的铜合金标样依照本法标定;丙酮氰醇(上海试剂总厂生产);2-(5-溴-吡啶偶氮)-5-二乙氨基苯酚:0.1%乙醇溶液;聚乙二醇辛基苯基醚(乳化剂OP):2.5%(V/V)。分析步骤称取0.1000克试样于250毫升锥形瓶中,加入2毫升浓盐酸及1毫升过氧化氢(30%),待试样溶解后加热使过氧化氢分解,加25毫升水。依次加入0.1克抗坏血酸、5毫升10%酒石酸钾钠溶液及10毫升三乙醇胺(1+2),摇匀,加氨水(1+1)中和至深蓝色,加入20毫升氨-氯化铵缓冲溶液及2 The masking effect of acetone cyanohydrin on copper (Ⅱ), zinc (Ⅱ), nickel (Ⅱ), cadmium (Ⅱ) and iron (Ⅱ) ions is similar to that of potassium cyanide but less toxic than potassium cyanide. To this end, the author developed by experiments ascorbic acid, tartaric acid, triethanolamine, acetone cyanogen alcohol and EDTA interference masking, with formaldehyde shielding, 5-Br-PADAP-OP as an indicator EDTA standard solution titration Manganese copper alloy The method of zinc. Method end sharp, good reproducibility. The main reagents EDTA standard solution: 0.01M and 0.02M, with a known amount of zinc content of copper alloy standard calibration in accordance with this law; acetone cyanohydrin (Shanghai Reagent Factory production); 2- (5- bromo - pyridine azo) Diethylaminophenol: 0.1% ethanol solution; polyethylene glycol octylphenyl ether (emulsifier OP): 2.5% (V / V). Analysis step Weigh 0.1000 grams of sample in a 250 ml Erlenmeyer flask, add 2 ml of concentrated hydrochloric acid and 1 ml of hydrogen peroxide (30%), dissolve the sample and heat until the hydrogen peroxide is decomposed, add 25 ml of water. Add 0.1 g of ascorbic acid, 5 ml of 10% sodium potassium tartrate solution and 10 ml of triethanolamine (1 + 2) successively, shake well, neutralize with ammonia water (1 + 1) to dark blue, and add 20 ml of ammonia-ammonium chloride buffer Solution and 2