Vol. 11, Issue 2, Part A (2025)

Abstract
This study presents the development of a simple, rapid, cost-effective, and accurate spectrophotometric method for the determination of Cephalexin (CPX) through anoxidative coupling reaction. The method involves the reaction of CPX with sodium periodate (SPI) as the oxidizing agent and amino phenazone (APh) as the coupling reagent, resulting in the formation of an orange chromophore upon completion of the reaction. This chromophore exhibits maximum absorption at 528 nm and remains stable for at least 35 minutes. The calibration curve follows Beer's law within a concentration range of 10-120 µg/mL, with a high correlation coefficient (R² =0.9996). The molar absorptivity was calculated to be 4793.982 L/mol.cm, and Sandell's sensitivity index was 0.0725 µg/cm². The limits of detection (LOD) and quantification (LOQ) were determined to be 0.01609 µg/mL and 0.05362 µg/mL, respectively. A recovery rate of 99.6865% was achieved, with a relative error of 0.3134% and a relative standard deviation (RSD) of 0.9373%. This method has been successfully applied to determine CPX in pharmaceutical formulations, including Cefex capsules and Pharmexin syrup.