Polarographic behaviour and determination of norfloxacin in tablets

Abstract

The direct current (dc) and differential pulse (dp) polarographic reduction of the antibacterial drug norfloxacin has been studied in various base electrolytes at different pH values in the presence of dimethyl formamide. Only one reduction wave in the range −0.95 to −1.05 V was observed in strongly acidic medium (pH < 1). Using a base electrolyte of pH ⩾ 7.5, two well defined irreversible waves were observed in the ranges of −1.48 to −1.67 V (wave C) and −1.79 to −1.93 V (wave D) for norfloxacin concentrations of 1 × 10 −4 M. These potential limits showed little shifts on both sides with norfloxacin concentration. At pH ⩾ 10, only wave D has been observed, but all waves disappeared completely in 0.1 M NaOH. In addition, two ill-defined waves appeared in the range −0.06 to −0.42 V within the pH range of 6.5–8.5 for norfloxacin concentrations > 5 × 10 −5 M. The single dp wave which appeared in 2 M HCl and the dp wave C which appeared in the other base electrolytes showed a useful rectilinear relationship between concentration and wave heights from 32 to > 560 μg ml −1 norfloxacin. These two dp waves have been utilized for determination of norfloxacin in Noroxin tablets with good recoveries. The polarographic behaviour of norfloxacin has been compared to that of nalidixic acid which has been also determined successfully in Negram tablets as the individual component and in the presence of norfloxacin as an interferent.