Spectrophotometric Determination of Mesalazine via Diazotization and Coupling With M-Aminophenol and Area Under Curve Methods
This study involves the development of an accurate, efficient, and low-cost spectrophotometric method for the determination of mesalazine (MSZE) in its pure state and various formulations. This process involves the coupling of diazotized MSZE with the reagent m-aminophenol (m-AP) in presence of sodium hydroxide (NaOH) medium to form a water-soluble azo dye with a maximum absorbance value at 470 nm. The method follows Beer's law in the concentration range of 0.5 - 10 μg/mL, with an excellent coefficient of determination (R2 = 0.9997), a molar absorptivity of 1.69 × 104 L/mol.cm², and a Sandell sensitivity index of 0.00906 μg/cm², and the detection limit (LOD) and quantification limit (LOQ) have also been estimated and their values were found to be 0.063 and 0.211 μg/mL, respectively. The second method is based on the area under the curve between 466 and 484 nm. The calibration curve for concentrations between 1 - 20 μg/mL with determination coefficient R2 = 0.9992. The second method is more sensitive than the first method, according to the value of molar absorptivity of 1.526 × 104 L/mol.cm². Both methods were applied to the analysis of MSZE tablet dosage from two different pharmaceutical companies, with good results.