KINETIC DETERMINATION OF CEPHALEXIN IN DRUG FORMULATIONS

A kinetic method for the accurate determination of cephalexin has been described. A solution of cephalexin is reacted with 5 x 10(-3)M cobalt(II) nitrate in 1 x 10(-3)M sodium hydroxide at 60-degrees-C for a fixed time of 6 min, after which the absorbance of the reaction product is measured at 310 nm. The concentration of cephalexin is calculated by using the corresponding calibration equation for the fixed-time method. The method has been applied to proprietary drugs and the results were compared statistically with those given by the BP method. The determination of cephalexin by the fixed-concentration and rate-constant methods is feasible with the calibration equations obtained but the fixed-time method has been found to be more applicable.