以meso-四(N-甲基-3-吡啶基)卟啉分光光度法测定微量银

SPECTROPHOTOMETRIC DETERMINATION OF TRACE SILVER WITH MESO-TETRA(3-N-METHYLPYRIDYL)PORPHYRIN

水溶性卟啉衍生物做为高灵敏度显色剂在分析化学中已经得到广泛应用。以卟啉为试剂用分光光度法可测定铜、镉、铁、铅、钯、钴、锌、锰、汞、镁和镍等金属离子,但尚未见用于银的测定。以其它试剂测定银的分光光度法很多,但灵敏度不太高。我们研究了以meso-四(N-甲基-3-吡啶基)卟啉〔简称T(3—MPy)P,图1〕测定银的分光光度法,灵敏度较高。

A sensitive method for the determination of silver with meso-tetra (3-N-methylpyridyl) porphyrin [T(3-MPy)P] has been developed, Silver reacts with T(3-MPy)P to form a 1:1 complex over the pH range 9.4—10.5, and the T(3-MPy)P remaining is converted into its lead complex by adding a small excess of lead(Ⅱ) after the silver complex was formed. The Soret band of the silver eomplex lies at 425.5 nm, which was well separated from that of the lead complex (472 nm). Apparent molar absorptivity of the silver complex is 3.56 ×10^(-5).