银-邻二氮菲-二溴荧光素光度法测定银的含量

Spectrophotometric Determination of Silver with Bibromoflurescein and O-Phenanthroline

研究了银 -邻二氮菲 -二溴荧光素离子缔合物体系在水溶液中的显色反应 .在pH7.1NH4 Ac缓冲介质中 ,PVA - 12 4存在下 ,形成 1∶2∶1型红色的离子型缔合物 ,λmax=5 40nm ,ε =4.2 9× 10 4 L·mol-1·cm-1,银含量在 0～ 5 0 μg/ 2 5mL范围内符合比尔定律 ,在EDTA存在下本文提出的测定银的新方法选择性好、灵敏度高 ,用于相纸、废定影液和废水中银的测定 ,有很好效果。

The color reaction of bibromoflurescein and O phenanthroline with silver(Ⅰ) was studied. In the presence of PVA 124,an red stable ion complex formed in molar ratio 1∶2∶1 at pH7.1(ammonium acetate buffer solution) by associated the silver(Ⅰ) with O phenanthroline and bibromoflurescein.The apparent molar absorptivity is 4.29×10 4 at the maximum absorption wavelength 540nm.Beer's law is obeyed in the range of 0～50μg/25mL for silver(Ⅰ).The method has a high selectivity and sensitivity in the presence of EDTA and has been applied to the determination of silver in photographic paper,fixer waste and industrial waste water with satisfactory results.