Analytical Studies on Pyrimidine Derivatives. V. Simple and Rapid Spectrophotometric Determination of Silver (I) with 5-p-Dimethylaminobenzylidene-2-thiobarbituric Acid

抄録

The spectrophotometric determination of silver (I) with 5-p-dimethylaminobenzylidene-2-thiobarbituric acid (DABTB) was studied and two simple and rapid methods are proposed. One is based on photometry of the DABTB-Ag (I) complex in ethanol-buffer (pH 6) solution (method A), and the other is based on measurement of the decrease in absorbance of DABTB due to the complex formation (method B). Beer's law holds over the range of 0.04-2 μg/ml of silver (I) at 400 nm in method A, and 0-35 μg of silver (I) at 484 nm in method B. The molar extinction coefficient of the complex is 2.5×10⁴·1·mol^-1·cm^-1 in method A. Hg (I, II), Au (III), Pd (II), Pt (IV), and various anions such as Br^-, Cl^-, I^-, SCN^-, CN^-, S₂O₃^2-, and S^2- interfered with the determination. These methods were successfully applied to the determination of silver (I) in commercial preparations such as silver nitrate eye lotion and silver protein.