青霉胺的巯基具有还原性,可将Fe(Ⅲ)还原Fe(Ⅱ),Fe(Ⅱ)能与2,2′-联吡啶形成桔红色的配合物,其最大吸收波长为524 nm,据此提出了分光光度法间接测定青霉胺药片中青霉胺含量的方法。优化的试验条件如下:① pH 4.5的0.2 mol·L-1乙酸-乙酸钠缓冲溶液用量为2.5 mL;② 0.2 g·L-1氯化铁溶液用量为2 mL;③ 1 g·L-1 2,2′-联吡啶溶液用量为2.5 mL;④ 显色时间为5 min。青霉胺的质量浓度在26 mg·L-1以内间接地与吸光度呈线性关系,检出限(3S/N)为0.01 mg·L-1。采用此法测定了青霉胺药片中青霉胺含量,所得测定值与标示量相符,测定值的相对标准偏差(n=5)为2.4%。

Based on the reduction of Fe(Ⅲ) to Fe(Ⅱ) by penicillamine due to its sulfhydryl group and on the color reaction between the Fe(Ⅱ) ion and 2,2′-bipyridine to give a reddish orange colored complex with its absorption maximum at the wavelength of 524 nm, a spectrophotometric method for indirect determination of penicillamine in penicillamine tablets was proposed. The optimized conditions found were as follows: ① amount of 0.2 mol·L-1 HOAc-NaOAc buffer solution of pH 4.5: 2.5 mL; ② amount of 0.2 g·L-1 FeCl3 solution: 2 mL;③ amount of 1 g·L-1 2,2′-dipyridine solution: 2.5 mL; ④ time of reaction: 5 min. Linear relationship between values of absorbance and mass concentration of penicillamine was obtained (indirectly) in the range less than 26 mg·L-1, with detection limit (3S/N) of 0.01 mg·L-1. The proposed method was used in the analysis of penicillamine tablets, giving results of penicillamine contents in consistency with the labelled value with RSD (n=5) of 2.4%.