Simultaneous determination of intact lomefloxacin and ciprofloxacin in the presence of their acid degradation products

ABSTRACT

A reversed phase HPLC method was developed for the determination of lomefloxacin and its degradation product. In addition, two other methods have been developed for the determination of lomefloxacin hydrochloride [LF.HCl] and ciprofloxacin hydrochloride [CF.HCl] in presence of their acid induced degradation products. For the reversed phase HPLC method [determination of LF.HCl], the mobile phase used was a mixture of water acetonitrile triethylamine [80200.6, v/v/v] adjusted to pH 3.0 with o-phosphoric acid. The flow rate was 1.5 ml/min. and the detection was carried out at 328 nm. The linearity range was found to be 0.5-6 micro g / 20 micro l for LF.HCl. The limits of detection and quantification [LOD and LOQ] were 0.22 micro g / 20 micro l and 0.74 micro g / 20 microl respectively. The second method was densitometric method for the determination of both LF.HCl and CF.HCl, the developing system used was a mixture of methanol and ammonia buffer [8020, v/v]. Detection was carried out at 288 nm and 279 nm. for intact LF.HCl and CF.HCl respectively. The linearity ranges were found to be 1-6 micro g / 10 microl and 0.25-2.5 micro g / 10 microl for intact LF.HCl and CF.HCl respectively. LOD and LOQ were 0.1, 0.34 micro g/10 microl and 0.05, 0.18 micro g /10 microl for both drugs, respectively. The third method was derivative spectrophotometric method for the determination of [LF.HCl] and [CF.HCL]. The linearity ranges were found to be 2-8 micro g/ml and 5-12 micro g/ml for LF.HCl and CF.HCl respectively. LOD and LOQ were 0.39 micro g, 1.29 micro g/ml and 1.03, 3.45 micro g/ml for LF.HCl and CF.HCl respectively. Separation and identification of the acid degradation products of lomefloxacin hydrochloride and ciprofloxacin hydrochloride were carried out. The three described methods proved to be sensitive, precise and applicable to both dosage forms and laboratory prepared mixtures of the intact drugs and their acid degradation products