电位滴定法研究^(99)Tc-HMDP和^(99)Tc-HEDP中Tc的氧化态

A study on the oxidation state of ^(99)TC in ^(99)Tc-HMDP and ^(99)Tc-HEDP by potentiometric titration

^(99)Tc-HMDP和^(99)Tc-HEDP溶液是在相应的螫合剂存在下,用过量SnCl_2还原^(99)TcO_4-制得。用标准I_2液对SnCl_2进行了剩余量电位滴定,确定了在pH～3的介质中,^(99)Tc-HMDP和^(99)Tc-HE-DP中^(99)Tc的氧化态均为+4。全部实验在N_2气流中进行。^(99)Tc-HMDP和^(99)Tc-HEDP的紫外光谱表明:在用I_2滴定的过程中,^(99)Tc只处于一种氧化态+4;将它们放置在空气中,一小时后仍较稳定。

Solutions of 99Tc-HMDP and 99Tc-HEDP were prepared by reducing 99TcO4- with excess SnCl2 in presence of corresponding chelating agent. The quantity of unreacted Sn-C12 was analyzed with I2 standard solution by potentiometric titration. It was found that 99TcO4- is reduced to the +4 state in either 99Tc-HMDP or 99Tc-HEDP at pH^3. The whole experiment was carried out under N2 atmospl ere. The UV spectrum of 'Tc-HMDP or 'Tc-HEDP shows that during the iodometric titration 99Tc exists only in one oxi. dation state and, they are stable in air within 1h.