Development and Validation of a Spectrophotometric Method for the Determination of Mesalazine Using an Azomethine Reagent in Pharmaceutical Preparations

Abstract

The study demonstrated that the color reaction between mesalazine and the azomethine reagent can be used as the basis for a suitable spectrophotometric method for the determination of mesalazine, as the product formed exhibited maximum absorption at 570 nm. An investigation of experimental conditions revealed that the spectral response is significantly affected by the amount of reagent, oxidizing agent, and acid, as well as by reaction time and temperature; optimal conditions were determined that yielded the highest and most stable response.The proposed method demonstrated a good linear relationship between absorbance and mesalazine concentration in the range of 5–70 µg mL⁻¹, while the LOD and LOQ values were 0.1844 and 0.5588 µg mL⁻¹, respectively, reflecting adequate sensitivity for the analytical range under study. Precision and reproducibility tests also showed an average recovery of 100.095% with low relative standard deviation values, indicating the consistency of the results and the method’s reproducibility.The results of the stoichiometric determination of the reaction, based on the methods of continuous changes and molar ratio, showed that the formation of the colored product occurs through a molar equivalence between mesalazine and the azomethine reagent, consistent with a 1:1 stoichiometric ratio. Based on the analytical characteristics obtained, the proposed method is characterized by simplicity, sensitivity, and accuracy, making it suitable for use in the determination of mesalazine in pharmaceutical preparations using ultraviolet-visible spectrophotometry.