试验表明:在微酸性或近中性的缓冲介质中加替沙星(GTXC)与刚果红(CGR)反应生成络合物导致后者的颜色减退.在pH 2.4~4.2的微酸性条件下反应时,其最大褪色波长位于616 nm处,在此波长测定时其线性范围在(0.05~2.98)×10-5mol·L-1之间,表观摩尔吸光率为1.84×104L·mol-1·cm-1;而在近中性的缓冲介质中(pH 4.5~7.5)反应时,最大褪色波长为508 nm,在此波长测定时其线性范围在(0.05~2.50)×10-5mol·L-1之间,表观摩尔吸光率为1.83×104L·mol-1·cm-1.根据结果提出了在不同酸度条件下GTXC的光度测定法,取3种市购GTXC注射液作为样品,按所提出的方法测定其中GTXC的含量,所得测定值与标示值相符.以此样品为基体加入GTXC标准溶液作方法的回收试验,测得回收率在98.5%~100.4%之间.

It was found that a complex was formed by the reaction of gatifloxacin (GTXC) with congo red (CGR),leading to decoloration of congo red in a slightly acidic buffer medium or in a nearly neutral buffer medium.Linear relationships were obtained between the values of decrease in absorbance and concentration of GTXC in the range of (0.05-2.98)×10-5mol·L-1,when reacted in pH range of 2.4-4.2 and measured at 616 nm,with apparent molar absorptivity of 1.84×104L·mol-1·cm-1,and in the range of (0.05-2.50)×10-5mol·L-1,when reacted in nearly neutral buffer medium of pH 4.5-7.5 and measured at 508 nm,with apparent molar absorptivity of 1.83×104L·mol-1·cm-1.A photometric method for determination of GTXC based on the above findings,in either slightly acidic medium or nearly neutral medium,was proposed.Three samples of GTXC injections were analyzed by the proposed method,giving results in conformity with the labelled values.Recovery tests were made by addition of GTXC standard solution to the injection samples,and values of recovery found were in the range of 98.5%-100.4%.