银微盘电极上头孢氨苄降解产物的伏安行为及其应用

Voltammetric Behaviour of the Degradation Product of Cephalexin at Silver Microdisk Electrode and Its Analytical Application

基于头孢氨华（ＣＥＸ）降解产物中含有巯基（－ＳＨ），能与Ａｇ＋生成难溶化合物的特性，在银微盘电极上研究了ＣＥＸ降解产物的伏安行为，探讨了电极反应的机理。运用示差脉冲溶出伏安法，在０．１ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ介质中，ＣＥＸ降解产物的还原峰电流与ＣＥＸ浓度于８．０×１０－８～７．０×１０－６ｍｏｌ／Ｌ范围内呈良好线性关系；检测限为１．０×１０－８ｍｏｌ／Ｌ；测定头孢氨苄胶囊中ＣＥＸ．含量为９２．０％，与药典法比较，相对误差为３．４％。

A cathodic stripping voltammetric method has been established for the determina- tion of cephalexin (CEX) on silver microdisk electrode. This method is based on the electro- chemical behaviour of the degradation product of CEX containing thiohydroxy group (-SH), which can combine with Ag+ to form an insoluble thiolate. The voltammetric behaviour of the degradation product and the electrode process mechanism were discussed. In pH 4. 5 HAc-NaAc medium the stripping peak currents are proportional to the concentration of CEX in the range of 8. 0 × 10-8 - 7. 0 × 10-6 mol/L by differential pulse stripping voltammetry. The detection limit is 8. 0 x10-8 mol/L. This methuti has been successfully applied to the determination of CEX in capsulae cephalexin and a mean value of 91. 98% is found. This re- sult is in agreement with that obtained by pharmacopoeial method.