毛细管区带电泳在氧氟沙星含量分析中的应用

Application of Capillary Zone Electrophoresis to Ofloxacin Determination

氧氟沙星（ＯＦ）是第三代喹诺酮类药物中效果最好的广谱抗菌素之一。由于它在ｐＨ２～１１范围内难溶于水与醇，给用ＨＰＬＣ法检测其含量带来一定困难。本文报告了用毛细管区带电泳（ＣＺＦ）分离检测该药的方法。由于使用ｐＨ调制样品引入技术，克服了其溶解性不好给ＨＰＬＣ法所带来的困难。其实验条件为：５０ｍｍｏｌ／Ｌ硼砂（ｐＨ１．５）为电泳缓冲液，２８０ｎｍ为紫外检测波长，２５ｋＶ为电泳电压。样品由高差进样方式引入分离毛细管（５．１２ｃｍ×５０μｍｉ．ｄ．，有效分离长度为３８．５ｃｍ）。用磺胺作内标，ＯＦ在４８～５３０ｍｇ／Ｌ及５８０～９７０ｍｇ／Ｌ范围内可进行定量分析。保留时间（ｔｒ）及相对紫外吸收（Ａ（样品）／Ａ（内标））的日内－ＲＳＤ值分别小于１．０％和２．４％（ｎ＝６）。

Ofloxacin is one of the best third-generation quinoline wide-spectrum antibiotics.Its limited solubility in water and alcohol in the pH range of 2～11, however, brings about some difficulty in its determination by HPLC. In this paper, a novel free-solution capillary electrophoresis method is proposed. The disadvantages of conventional HPLC method, such as the insolubility of the antibiotics and the use of toxic organic solvents(methyl alcohol and acetonitrile),have been overcome by using a pH-mediated sample introduction technique. Separation was carried out at 25 ±1℃ in an untreated fused-silica capillary(51.2cm×50μm i. d. with an effective separation length of 38. 5 cm) with 50 mmol/L borax buffer(pH 1. 5) and 25 kV applied voltage. The analyte was introduced into the separation capillaty via a high pressure -difference module at 10 cm for 20s and the Ofloxacin (OF) concentration was determined by a UV detector at 280 nm. The linear ranges are 48～530 and 580～970 mg/L with sulfanilamide(SA) as an internal standard. The intra-day RSD values of retention time(t_r) and relative UV absorbance(A_(OF)/A_(SAD)) are less than 1.0%and 2. 4%(n= 6), respectively.