THIN-LAYER CHROMATOGRAPHY WITH DENSITOMETRY FOR THE DETERMINATION OF DIFLOXACIN AND ITS PHOTODEGRADATION PRODUCTS. KINETIC EVALUATION OF THE DEGRADATION PROCESS AND IDENTIFICATION OF PHOTOPRODUCTS BY MASS SPECTROMETRY

Abstract

TLC-densitometric method was developed for determination of difloxacin (DIF) in the presence its photodegradation products. Silica gel TLC F₂₅₄ plates were used as the stationary phase and methylene chloride:methanol:2-propanol:ammonia 25% (4:4:5:2, v/v/v/v) as the mobile phase. The elaborated method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. The photodegradation process of DIF followed kinetics of the first order reaction for the substrate. Potential photodegradation products of DIF identified by UPLC-MS/MS are: 7-(2-aminoethylamino)-6-fluoro-1-(4-fluorophenyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, 7-amino-6-fluoro-1-(4-fluorophenyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, 6-fluoro-1-(4-fuorophenyl)-7-(3-hydroxypiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, 6-fluoro-1-(4-fuorophenyl)-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid.

Keywords:

• difloxacin
• kinetic evaluation
• mass spectrometry
• method validation
• photodegradation
• TLC

Notes

a-y-intercept.

b-Slope of regression line.

c-Quadratic term.

RSD – relative standard deviation.