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 (80:20:0.6, 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 μg / 20 μl for LF.HCl. The limits of detection and
quantification (LOD & LOQ) were 0.22 μg / 20 μl & 0.74 μg / 20
μl 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 (80:20, v/v).
Detection was carried out at 288 nm & 279 nm. for intact LF.HCl
and CF.HCl respectively. The linearity ranges were found to be 1-6
μg / 10 μl & 0.25-2.5 μg / 10 μl for intact LF.HCl and CF.HCl
respectively. LOD & LOQ were 0.1, 0.34 μg / 10 μl & 0.05, 0.18 μg
/ 10 μl for both drugs, respectively.
The third method was derivative spectrophotometric method for
the determination of (LF.HCl) & (CF.HCL). The linearity ranges
were found to be 2-8 μg/ml & 5-12 μg/ml for LF.HCl and CF.HCl
respectively. LOD & LOQ were 0.39 μg, 1.29 μg/ml & 1.03, 3.45
μg/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.