铁(Ⅲ)-硫氰酸钾体系褪色光度法测定硫普罗宁含量

Determination of Tiopronin by Fading Spectrophotometry in Iron ( Ⅲ ) Potassium Thiocyanate System

酸性介质中,铁(Ⅲ)与硫氰酸钾生成最大吸收波长为445nm的血红色配合物,加入的硫普罗宁将溶液中的Fe(Ⅲ)还原为Fe(Ⅱ),导致溶液吸光度减小。测定配合物溶液与硫普罗宁反应前后的吸光度记为A0、A,吸光度变化值ΔA=A0-A。结果表明,加入的硫普罗宁浓度c(x/mg·m L^(-1))在0~0.14 mg·m L^(-1)范围内,与ΔA(y)有良好的线性关系,其线性回归方程为y=0.8149x+0.0006,线性相关系数r=0.9997。方法用于硫普罗宁肠溶片中硫普罗宁含量的测定,结果与国家药品标准测定结果相近,有一定的应用价值。

Iron（ Ⅲ） ions and potassium thiocyanate could generate blood-red complexes in acidic medium which had maximum absorption wavelength of 445 nm. When tiopronin was added into iron（ Ⅲ） potassium thiocyanate system, iron（ Ⅲ） ions were reduced to iron（ Ⅱ） ions, and the absorbance of blood-red complexes would fall down. The reduction of absorbance ΔA（y） had good linear relationship with the contents of tiopronin（x） from 0 mg/m L to 0.14 mg/m L. The linear regression equation was y=0.8149 x＋0.0006 and the related coefficient r=0.9997. The concent of tiopronin in Tiopronin Enteric-coated Tablets was determined by this method and the result was similar to which detected by national drug standard.