el-Gindy A, Korany M A, Bedair M F
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia, Egypt.
J Pharm Biomed Anal. 1998 Sep;17(8):1357-70. doi: 10.1016/s0731-7085(98)00041-7.
Two methods are presented for the determination of cinchocaine HCl in presence of its acid-induced degradation product using first (1D) derivative spectrophotometry and high-performance liquid chromatography. Cinchocaine HCl was determined by measurement of its first derivative amplitude at the zero crossing point of 2-hydroxyquinoline-4-carboxylic acid diethylaminoethylamide as its acid degradation product (at 333.5 nm). The HPLC method depends upon using a mu Bondapak C18 column at ambient temperature with a mobile phase consisting of acetonitrile--0.01 M sodium acetate trihydrate (45:55, v/v) containing 0.06% (w/v) heptane sulphonic acid sodium salt and adjusted to apparent pH 4.5 with acetic acid at a flow rate 2 ml min-1. Quantitation was achieved with UV detection at 254 nm based on peak area. The HPLC method was applied for simultaneous determination of cinchocaine HCl, methylparaben and propylparaben. The two proposed methods were successfully applied to the determination of the cinchocaine HCl in laboratory-prepared mixtures in the presence of its acid degradation product and in cream. Moreover, the proposed methods were utilized to investigate the kinetics of the acid degradation process at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy calculated.
本文介绍了两种方法，用于在存在酸诱导降解产物的情况下测定盐酸辛可卡因，分别采用一阶（1D）导数分光光度法和高效液相色谱法。通过测量其酸降解产物2-羟基喹啉-4-羧酸二乙氨基乙酰胺在零交叉点（333.5nm）处的一阶导数幅度来测定盐酸辛可卡因。高效液相色谱法是在室温下使用μ Bondapak C18柱，流动相由乙腈 - 0.01M三水合醋酸钠（45:55，v/v）组成，其中含有0.06%（w/v）庚烷磺酸钠盐，并用醋酸调节至表观pH 4.5，流速为2 ml min-1。基于峰面积，在254nm处用紫外检测进行定量。高效液相色谱法用于同时测定盐酸辛可卡因、对羟基苯甲酸甲酯和对羟基苯甲酸丙酯。所提出的两种方法成功应用于在其酸降解产物存在的情况下测定实验室制备混合物以及乳膏中的盐酸辛可卡因。此外利用所提出的方法研究了不同温度下酸降解过程的动力学，并计算了表观伪一级速率常数、半衰期和活化能。
