Thermodegradation Kinetics of the New Antibacterial Fluoroquinolone Derivative, Sparfloxacin, in Aqueous Solution

Abstract

The degradation kinetics of sparfloxacin (5-amino-1-cyclopropyl-7-(cis-3, 5-dimethyl-1-piperazinyl)-6, 8-difluoro-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid) were examined as functions of pH (1.0-10.5), temperature (100-120°C) and buffer concentration (0.01-0.05 M).The degradation kinetics for sparfloxacin in aqueous solution followed a pseudo-first-order reaction under all experimental conditions. No appreciable effect of buffer species on the degradation of sparfloxacin was observed within the experimental conditions. The log k-pH profiles showed specific-acid catalysis at a pH below 4.0, and there were inflection points near pH 6 and 9 corresponding to the pK_a1 and pK_a2 values. Arrhenius data in this study showed that the degradation of sparfloxacin was negligible at room temperature between pH 1.0-10.5.