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目前国内对无氰或有氰电镀液中焦磷酸根离子的测定方法,多是基于先形成锌盐沉淀,然后用EDTA溶液滴定过量锌离子。但是一般工厂反映测定结果误差较大。为此对该方法进行了试验。用锌盐法测定电镀液中焦磷酸根离子的操作步骤为: 取1毫升试液加50毫升水3滴PAN指示剂,用0.05M EDTA溶液滴定以络合铜离子。用乙酸调节溶液的pH=3.8～4(用精密pH纸)。然后加入20.00毫升0.2M标准乙酸锌溶液,煮沸1分钟,冷却,过滤,洗涤沉淀数次。在滤液中加入10毫升铵盐缓冲溶液,用0.05M EDTA溶液滴定过量锌离子;或用氨
At present, the determination of pyrophosphate ion in cyanide-free or cyanide plating solution is mainly based on the first formation of zinc salt precipitation, and then titration of excess zinc ions with EDTA solution. However, the general factory measurement results reflect the larger error. To this end the method was tested. The zinc salt method for the determination of pyrophosphate ions in the electroplating solution steps: Take 1 ml of test solution plus 50 ml of water 3 drops of PAN indicator, titration with 0.05 M EDTA solution to complex copper ions. Adjust the pH of the solution with acetic acid = 3.8 to 4 (using precision pH paper). Then 20.00 ml 0.2 M standard zinc acetate solution was added, boiled for 1 minute, cooled, filtered and the precipitate was washed several times. To the filtrate was added 10 ml ammonium salt buffer solution, with 0.05 M EDTA solution titration excess zinc ions; or with ammonia