Thermodynamic study and spectrophotometric determination of cefixime trihydrate in pure form and pharmaceutical tablets using batch and normal flow injection analysis

This study aimed at developing pectrophotometric methods for the determination of Cefixime Trihydrate [CFT] by simple, sensitive batch and flow-injection analysis in its purest form and tablet formulations. These developed methods were based on an oxidative coupling reaction of CFT with thaimine hydrochloride in the presence of a basic medium and using potassium ferricyanuide as an oxidant to produce a stable water-soluble, intense orange dye with a maximum absorption at 440 nm. Beer s law was followed over the concentration range [2.5-75 and 10-400 μg.mL^-1] of CFT with limits of detection of 0.7223 and 2.6145 μg.mL^-1 of CFT for batch and FIA methods, respectively. The average sample throughput for the FIA was 68 h^-1. The effects of various chemical and physical experimental parameters on the development and stability of the colored product were carefully investigated. CFT estimated in commercial tablets forms was successfully applied using these methods, in which the results were in good agreement with those produced using the official procedure. Thermodynamic parameters, including the free energy changes [ΔG], enthalpy [ΔH] and entropy [ΔS] were determined at different temperatures for the reaction product.