Bakry R S, el Walily A M, Belal S F
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Egypt.
Acta Pharm Hung. 1995 Jul;65(4):113-7.
A simple and rapid method for the determination of etilefrine hydrochloride and ritodrine hydrochloride, either in pure form or in pharmaceutical formulations, is described. The method is based on the development of red product in presence of sodium nitrite and cobalt(II) salt in acid medium. The reaction is thought to proceed via preliminary nitrosation of the phenolic nucleus followed by formation of the chelate in presence of cobalt(II) salt. The highly colored chelates showed wavelengths of maximum absorption of 570 and 560 nm for etilefrine hydrochloride and ritodrine hydrochloride, respectively. The reaction product showed apparent molar absorptivities of 938 and 2930 L mol-1 cm-1 for etilefrine hydrochloride and ritodrine hydrochloride, respectively. A linear correlation was found between absorbance (at the lambda max) and concentration in ranges of 0.08-0.20 and 0.04-0.10 mg ml-1 for etilefrine hydrochloride and ritodrine hydrochloride, respectively. At the same time, the resulting colors were well developed within 25 min at boiling water bath temperature and were stable for more than 1 hr. Results of analysis of pure drugs and their dosage forms by the proposed method were in good agreement with either a reported derivative spectrophotometric procedure or the USP XXII method for etilefrine hydrochloride and ritodrine hydrochloride, respectively. The validity of the method was further confirmed using the standard addition method. The proposed method demonstrate high percentage of recovery with good accuracy and precision.
本文描述了一种简单快速的方法，用于测定纯品或药物制剂中的盐酸乙苯福林和盐酸利托君。该方法基于在酸性介质中，亚硝酸钠和钴（II）盐存在下生成红色产物。反应被认为是通过酚核的初步亚硝化，然后在钴（II）盐存在下形成螯合物进行的。对于盐酸乙苯福林和盐酸利托君，高度显色的螯合物的最大吸收波长分别为570和560 nm。反应产物对盐酸乙苯福林和盐酸利托君的表观摩尔吸光系数分别为938和2930 L·mol⁻¹·cm⁻¹。在0.08 - 0.20和0.04 - 0.10 mg·ml⁻¹范围内，盐酸乙苯福林和盐酸利托君的吸光度（在最大波长处）与浓度之间分别存在线性关系。同时，在沸水浴温度下25分钟内显色良好，且稳定超过1小时。用所提出的方法对纯药物及其剂型进行分析的结果，分别与报道的盐酸乙苯福林和盐酸利托君的导数分光光度法或美国药典XXII方法的结果良好吻合。使用标准加入法进一步证实了该方法的有效性。所提出的方法显示出高回收率，具有良好的准确度和精密度。
