[Ultraviolet spectral characteristics of charge-transfer reaction complex in micellar system and its application]

Charge-transfer (CT) reaction of chloranil (TCBQ) as a pi-electron acceptor with fleroxacin (FLX) as an electron donor has been studied by ultraviolet spectrophotometry method. Experiment showed that FLX reacted with TCBQ in sodium dodecyl sulfate (SDS) micellar systems, and a stable complex was formed and the absorbency was remarkably enhanced. Therefore, a simple, rapid, accurate and sensitive method for the determination of FLX has been developed. Beer's law is obeyed in the range of 0.6-24 mg x L(-1) of FLX and r = 0.9993. The apparent molar absorptivity of CT complexes at 326 nm is 3.3 x 10(4) L x mol(-1) x cm(-1). The composition of CT complex was found to be 1:1 by Bent-French and curved intersection methods. The proposed method has been applied to the determination of ESL in tablets. The recoveries are 99.2%-99.7%. The relative standard deviation is 0.7%-2.1%. The proposed methods are suitable for the routine quality control of drug alone and in tablets or capsules without fear of interference caused by the excipients expected to be present in tablets or capsules.