SPECTROPHOTOMETRIC DETERMINATION OF CIPROFLOXACIN IN PURE FORM AND INTABLETS THROUGH CHARGE-TRANSFER COMPLEXATION REACTIONS

Three simple, quick and sensitive spectrophotometric methods are descr ibed for the determination of ciprofloxacin. The methods are based on the reaction of this drug as an n-electron donor with 2,3-dichloro-5,6 -dicyano-p-benzoquinone (DDQ), 7,7,8,8,-tetracyanoquinodimethane (TCNQ ) and p-chloranil (CL) as pi-acceptors to give highly coloured complex species. The coloured products are quantitated spectrophotometrically at 460, 843 and 550 nm for DDQ, TCNQ and CL, respectively. Optimizati on of the different experimental conditions is described. Beer's law i s obeyed in the concentration ranges 5-50, 1.5-15 and 20-200 mu g ml(- 1) ciprofloxacin, but the concentration ranges for best accuracy are 1 0-48, 2.5-15 and 35-195 mu g ml(-1) of drug for DDQ, TCNQ and CL, resp ectively. The relative standard deviations are less than 1.5%. Applica tions of the suggested methods to ciprofloxacin tablets are presented and compared with the USP method. The stability constants of the 1:1 D DQ and CL complexes were 1.086 x 10(4) and 2.581 x 10(4) l mol(-1), re spectively, whereas for the 1:2 TCNQ complex it was 3.62 x 10(8) l mol (-1).