meso—四(4—烟酰胺基苯基)卟啉分光光度法测定超微量铜的研究

STUDY ON THE SPECTROPHOTOMETRIC DETERMINATION OF ULTRAMICRO AMOUNT OF COPPER (Ⅱ) WITH meso-TETRAKIS (4-NIACINAMIDOPHENYL) PORPHYRIN

研究新的非水溶性meso—四(4—烟酰胺基苯基)卟啉[简称T(4—NAP)PH_2]在表面活性剂存在下测定Cu(Ⅱ)显色反应的最佳条件。结果表明,该卟啉与Cu(Ⅱ)形成稳定性好、灵敏度高的配合物,其ε_(418)=4.20×10~5,Cu(Ⅱ)在0～3.5μg/25mL范围内遵守比耳定律。用本法测定Cu(Ⅱ)干扰小,可不经分离而直接测定钢铁、自来水中的痕量铜。

The complex reaction of Cu (Ⅱ) with the water-insoluble porphyrin, meso-tetrakis(4-niacinamidophenyl) porphyrin, T(4-NAP) PH_2 in the presence of anionic surfaetant, sodium dodeeylsulfate and small amount of hydroxylamine was studied. The complex formation is slow at room temperature, however, it can be accelerated by heating and completed within7min on boiling water bath. The T(4-NAP)PH_2 was found to be a highly sensitive and selective reagent for the direct speetrophotometric determination of ultramicro amount of copper (Ⅱ). The Soret band of the complex lies at 418.0 rim, which is well separated from that of diacid form of T(4-NAP)PH_2 (as a reference) at 452.5 nm. The molar absorptivity of the complex is 4.20×10~5L·mol^(-1) cm^(-1) at pH4.6. Beer's law is obeyed for Cu(Ⅱ) in the range of 0—3.5μg/25mL. The complex is highly stable. The interference of 15 ions and 5 salts was examined and found to be minimal. This simple and rapid method has been applied to the direct determinations of ultramicro amount of copper in steel and tap water with satisfactory results.