盐酸洛美沙星水溶液的光降解动力学研究

目的　考察盐酸洛美沙星水溶液的光降解动力学特征。方法　使用HPLC分离分析技术确定盐酸洛美沙星水溶液在不同pH值缓冲溶液、不同离子强度不同离子条件下水溶液、不同介电常数溶液中经光照处理的光降解动力学参数。结果　经线性拟合对比分析，盐酸洛美沙星水溶液的光降解反应级数为n=1；盐酸洛美沙星在pH5.08-9.40缓冲溶液中对光最不稳定，在pH2.02-5.08及9.40-11.10的缓冲溶液中对光相对稳定；洛美沙星盐酸水溶液的光降解随离子强度的增加降解速率也增加，在水溶液中氯离子对其光降解有极大影响并生成高产率的氯取代衍生物；溶液的介电常数增加，其光降解速率也增加。结论　盐酸洛美沙星水溶液光降解属近似一级动力学过程，光解速率受溶液pH影响显著，光解速率与溶液中的离子强度呈正向相关并存在氯离子的特殊盐效应，与溶液的介电常数呈正相关。

STUDY ON PHOTODEGRADATION KINETICS OF LOMEFLOXACIN HYDROCHLORIDE AQUEOUS SOLUTION

AIM: To investigate the photodegradation kinetic characteristics of lomefloxacin hydrochloride aqueous solution. METHODS: The HPLC method was used to determine the photodegradation kinetic parameters of lomefloxacin hydrochloride aqueous solution (10 micrograms.mL-1) under various pH buffer solutions, various ionic strength of different ions and various dielectric constant conditions. RESULTS: With comparative regression analysis of linear fit, the photodegradation kinetic order of lomefloxacin hydrochloride aqueous solution was determined as n = 1. The lomefloxacin hydrochloride aqueous solution is most unstable at pH 5.08-9.40 and is relatively stable at pH 2.02-5.08 and 9.40-11.10. The higher the ionic strength in lomefloxacin hydrochloride aqueous solution, the higher the photodegradation kinetic rate constant is. The chloride ion has important effect on photodegradation in aqueous solution of lomefloxacin and results in producing chlorine derivative as the highest photodegradation product. As the dielectric constant of solution increased, the photodegradation kinetic rate constant was also increased. CONCLUSION: It was found that the photodegradation of lomefloxacin followed apparent first-order kinetics. The photodegradation kinetic rate was affected by pH remarkably and showed positive correlation with ionic strength and dielectric constant.