DETERMINATION OF DANOFLOXACIN AND ITS PHOTODEGRADATION PRODUCTS BY THIN-LAYER CHROMATOGRAPHY: KINETIC EVALUATION OF DEGRADATION PROCESS

Abstract

TLC-densitometric method was developed for determination of danofloxacin (DAN) in presence of its photodegradation products. Silica gel HPTLC Lichrospher 60 F₂₅₄ plates were used as the stationary phase and methanol:acetone:1 M citric acid:triethylamine (2.8:2:0.2:0.5, v/v/v/v) as the mobile phase. The elaborated method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. The linear regression analysis for the calibration curve showed a good linear correlation over the concentration range 1.25– 3.75 µg per band, with determination coefficient, exceeding 0.9806. Accuracy of the method expressed as % recovery at three concentration levels was from 95.56% to 97.30%. Good precision and intermediate precision with % RSD less than 0.92% was also observed. The limits of detection and quantification were respectively 1.10 and 3.40 ng per band. Satisfactory results of validation of the method were also confirmed by determination of DAN in veterinary commercial preparation. The photodegradation process of DAN followed kinetics of the first order reaction for the substrate.

Keywords:

• danofloxacin
• determination
• kinetic evaluation
• method validation
• photodegradation
• TLC

Notes

*k = (1 – R_F)/R_F.

k, retention factor. Rs, resolution factor; Rs = 2x(distance between the centers of two adjacent spots)/(sum of the widths of the two spots in the direction of development).

A, separation factor; α = [(1/R_F1) − 1]/[1/R_F2) − 1].

RSD, relative standard deviation.

x_m, mean; SD, standard deviation.