Determination of sparfloxacin and its photodegradation products by thin-layer chromatography with densitometry detection. Kinetic evaluation of the degradation process and identification of photoproduct by mass spectrometry

Abstract

A TLC-densitometric method was developed for the determination of sparfloxacin in the presence of 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 developed 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 1.00–3.00 μg per band, with the determination coefficient, R², exceeding 0.9958. The method was shown to have good precision and intermediate precision, as reflected by the relative standard deviation values, lower than 2.72% and characterized by a recovery rate at three concentration levels from 93.60% to 103.90%. The limits of detection and quantification were respectively 0.16 and 0.48 μg per band. The photodegradation process of sparfloxacin followed the kinetics of a first order reaction for the substrate. Nine products of photodegradation were identified by UPLC-MS/MS. The structure of a product previously not identified was determined.