盐酸强力霉素在几种溶剂体系中的溶解度测定

利用盐酸强力霉素在不同比例的乙醇—水溶剂中的溶解过程所出现pH值的改变,测定它在该溶液中的溶解度。把此数据与观察法、差重法所测得的数据相比较基本吻合,而以pH值法求得的较为准确。 盐酸强力霉素在乙醇—水溶剂中的溶解平衡为一级弱酸电离平衡。其溶解度随溶液中水组分的增加而增大,并随温度的升高而增大;在乙醇—盐酸溶液中用差重法测得的溶解度规律是随盐酸含量的增加,溶解度减小,温度升高溶解度增大;在盐酸—乙醇—水溶剂中,溶解度规律是随盐酸的含量增加,溶解度减小。

THE SOLUBILITY DETERMINATION OF DOXYCYCLINE HYDROCHLORIDE IN SOME SOLVENT SYSTEMS

The solubility of doxycycline hydrochloride in C_2H_5OH-H_2O solvent system had been determined and measured by the change of the pH value of the solution. This method was called pH value method. Results showed that the data obtained by this method conformed to those of using observed and weight difference methods. In the C_2H_5OH-H_2O system, when the solution equilibrium attained, doxycycline hydrochloride has its first degree dissociation equilibrium as a weak acid The more the water and the higher the temperature, the greater the solubility of the doxycycline hydrochloride were in the solvent system. while in the case of HC1-C_2H_5OH system, results determined by weight difference method showed that the more the HC1 the smaller the solubility, and the higher the temperature, the greater the solubility of the antibiotic in the system; and in the HC1-C_2H_5OH-H_2O system, the more the HC1 contains the smaller the solubility of the substance.