High-pressure liquid chromatographic methods for ciprofloxacin hydrochloride and related compounds in raw materials

High-pressure liquid chromatographic (HPLC) methods were developed for the analysis of ciprofloxacin hydrochloride raw materials. Method A is for drug content and the determination of related compounds eluting before the drug, including the ethylenediamine analog of ciprofloxacin. Method B may be used for the determination of fluoroquinolonic acid and other related compounds eluting after the drug. Both methods require a 5 microns Inertsil ODS2 column (150 x 4.6 mm), a mobile phase containing tetrahydrofuran, acetonitrile and buffer (0.005 M 1-hexane-sulphonic acid sodium adjusted to pH 3.0 with 0.1 M phosphoric acid); 10:5:85 (v/v/v) for method A and 25:15:60 (v/v/v) for method B, and a flow rate of 1 ml min-1. Detection for method A is at 254 nm; a programmable variable wavelength detector is required for method B: 254 nm for 12 min, then 220 nm for 23 min. The limit of quantitation of the related compounds was 0.05% or less. The precision of the assay method was lower than 1.0%. Drug content in four raw material samples ranged from 98.7% to 101.6% calculated with reference to the anhydrous substance. The water content in these samples ranged from 5.9% to 7.8%. Total impurity levels were 1.0% or lower. Levels of ethylenediamine analog and fluoroquinolonic acid were below 0.4%. A second analyst, using a different HPLC system and a column from a different supplier, repeated the analysis of two raw materials samples and obtained similar results.