氮川三甲撑膦酸(NTMP)对铜的螯合滴定已有报道其滴定的选择性比EDTA或NTA 为优。但因Cu~(2+)和Zn~(2+)与NTMP形成螯合物的稳定常数差别不太大,故用铬天青S作指示剂螯合滴定铜时,Zn~(2+)的容许量很少。我们发现,用铂电极作指示电极、NTMP电位滴定铜时,Zn~(2+)的容许量可以提高,用于一些铜基锌合金中铜的分析,结果满意。试剂及仪器 0.01358mol·L~(-1)NTMP溶液:按文献配制並标定;10％六次甲基四胺缓冲溶液,用HCL调pH5.5。 pH S-2型酸度计;213型铂电极;215型钨电极;78-1型磁力搅拌器。试验方法在100mL烧杯中,加入3.18mg铜並加水至约50mL,加10mL六次甲基四胺缓冲溶液,扦入铂钨电极,启动搅拌器,用NTMP溶液进行电位滴定。记录毫升数(V)和相应的电位值(E),用 Chelate titration of trimethylammonium phosphonate (NTMP) to copper has been reported to be more selective than EDTA or NTA for titration. However, because of the difference between the stability constants of Cu 2+ and Zn 2+ forming chelates with NTMP is not too large, when using chrome azure S as chelating agent to titrate copper, Little tolerance. We found that, with Pt electrode as the indicator electrode, NTMP potential titration of copper, Zn ~ (2 +) tolerance can be increased for some copper-based zinc alloy copper analysis with satisfactory results. Reagents and equipment 0.01358mol · L -1 NTMP solution: prepared and calibrated according to the literature; 10% hexamethylenetetramine buffer solution, adjusted to pH5.5 with HCL. pH S-2 pH meter; Type 213 platinum electrode; Type 215 tungsten electrode; Type 78-1 magnetic stirrer. Test Method In a 100mL beaker, add 3.18mg copper and add water to about 50mL, add 10mL hexamethylenetetramine buffer solution, cut into the platinum tungsten electrode, start the mixer, NTMP solution potentiometric titration. Record milliliters (V) and the corresponding potential value (E), with