Generic Nonextractive Spectrophotometric Method for Determination of 4-Quino-Naphthollone Antibiotics by Formation of Ion-Pair Complexes with -Naphthol

Abstract

Abstract This paper describes the development of a generic spontaneous nonextractive spectrophotometric method for determination of 13 pharmaceutically important 4-quinolone antibiotics. The method was based on the formation of yellow-colored water-soluble ion-pair complexes between 2% (w/v) -naphthol reagent and each of the studied drugs in sulfuric acid medium at room temperature. The formed ion-pair chromogens have maximum absorption peaks in the range of 365391 nm. The concentrations of the reagents and the experimental conditions affecting the reaction were optimized. Under the optimum conditions, linear relationships with good linear coefficients (0.99870.9995) were found between the absorbance and concentration of the investigated drugs in the range of 10350 g/mL. The assay limits of detection and quantitation were 19.9 and 3.432.9 g/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the analysis of the investigated drugs in pure and pharmaceutical dosage forms with good accuracy and precision; the percentages of label claim ranged from 97.8102.8 0.351.60%. The results obtained by the proposed spectrophotometric method were comparable with those obtained by the official or reported methods. The proposed method is superior to all the previously reported ion-pair formation-based methods in terms of simplicity because it did not involve extraction procedures for the ion-pair complex. Therefore, this method might be recommended for routine use in quality control laboratories for analysis of the investigated 4-quinolone antibiotics in their pure forms, as well as in pharmaceutical dosage forms.