铬天青S分光光度法测定明胶空心胶囊中微量铬

采用分光光度法测定明胶空心胶囊中微量铬。亚硫酸钠将Cr（Ⅵ）还原为Cr（Ⅲ），在pH=4．7的乙酸-乙酸钠缓冲体系中，以乳化剂OP为增敏剂，Cr（Ⅲ）与铬天青S生成蓝紫色络合物。该络合物在537nm处有最大吸收，表观摩尔吸光系数为7．2×10^4L·mol^-1·cm^-1。铬在0-0．12μg／mL之间呈良好的线性关系，相关系数为0．9995，回收率在86．7％-108％之间。

Determination of Trace Chromium in the Vacant Gelatin Capsules by Chomeazurol S Spectrophotometry

A new method was established to detect trace chromium in the vacant gelatin capsules by spec- trophotometry. Cr （Ⅵ） was reduced to Cr （Ⅲ） by Sodium sulfite. Cr （Ill） reacted with Chromazurol S to forma blue purple complex in the HAc-NaAc buffer system of pH 4. 7, with emulsifier OP as sensitizer. The maximum absorption wavelength of the complex was 537 nm, the apparent molar absorptivity was 7.2 ×10^4L·mol^-1·cm^-1. The absorbance was proportional to the concentration of chromium, the calibration curve was linear within the range of 0 -0. 12 μg/mL with a correlation coefficient of 0. 9996. The recovery rate was 86. 7% to 108%. The method is simple, reliable, and low cost.