A rapid and sensitive spectrophotometric method for the determination of Cephalexin using 2,4-dinitrophenylhydrazine in pharmaceutical products

A simple, applied method for determining cephalexin in pharmaceutical formulations was used by UV-Vis spectrophotometry. The procedure is followed by the oxidative reaction between cephalexin and the C-nitro compound, 2,4-dinitrophenylhydrazine (2,4-DNPH) in an alkaline medium. Then, the reaction created an intensely coloured product, which was adsorbed by UV-Vis at 618 nm as the cephalexin concentration. The variable parameters, such as reagent dosage, sample pH, and reaction time, were studied and optimized. Therefore, based on Beer–Lambert’s law, the concentration range and molar absorptivity were obtained at 10–300 µg mL⁻¹ and 3.23 × 10³ L mol⁻¹ cm⁻¹, respectively. The limit of detection (LOD) and Sandell’s sensitivity were achieved at 1.12 µg mL⁻¹ and 0.108 µg cm⁻². The proposed method demonstrated good accuracy and precision and was successfully applied to the determination of cephalexin in commercial pharmaceutical formulations without significant interference from common excipients. This method offers a rapid and economical alternative to more sophisticated chromatographic techniques, making it suitable for routine quality control analysis. The method was validated according to standard analytical parameters, including accuracy, precision, and recovery, demonstrating excellent reliability for routine quality control applications.