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NTMP(氮川三甲撑膦酸)是一种有机磷酸化合物。据报道NTMP可作金属离子沉淀剂和滴定剂,但未见有用作掩蔽剂的报道,由于NTMP分子中含有六个可解离的氢,与EDTA相比多两个可解离的氢,因此,两者与金属离子生成的络合物的稳定性受溶液酸度影响的程度是不同的。据此,我们在前文以NTMP作掩蔽剂用EDTA光度滴定铜方法的基础上、以二甲酚橙为指示剂,用EDTA光度滴定Pb~(2+)、Zn~(2+)、Bi~(3+)、Sc~(3+)为对象,进一步考察了NTMP的掩蔽性能,试验证明,一定量的Fe~(3+)、Th~(4+)、Ti~(4+)、Sn~(4+)等单独或混合同时存在,不干扰滴定。 1 试验部分1.1 主要试剂与仪器
NTMP (nitrilotrisphosphonic acid) is an organophosphoric acid compound. It has been reported that NTMP can be used as a metal ion precipitating agent and titrant, but there are no reported reports as masking agents. Since NTMP contains six dissociable hydrogens and two more dissociable hydrogens than EDTA, , The stability of the complex formed between the two with metal ions is affected by the acidity of the solution to a different degree. Therefore, based on the method of titrimetric titration of copper by EDTA with masking agent of NTMP, we use photometric titration of Pb2 +, Zn2 +, Bi2 + (3 +) and Sc ~ (3+) as targets, the masking properties of NTMP were further investigated. The results show that a certain amount of Fe 3+, Th 4+, Ti 4+, Sn ~ (4 +), etc. exist alone or in combination without disturbing the titration. 1 Experimental 1.1 The main reagents and equipment