Method development and analytical validation for methyldopa determination in pharmaceutical dosage forms

Abstract

This research focused on optimizing experimental conditions to achieve maximum spectral absorption in the determination of methyldopa. The results demonstrated adherence to Beer – Lambert’s law with excellent linearity within concentration range of 5 – 40 μg/mL and a high coefficient of determination ( R 2 , approximately 0.9992). The structural formula of the resulting-colored complex was determined using Job’s method and molar ratio analysis, confirming a 1:1 covalent ratio between the reagent and the drug. Stability constant analysis revealed high chemical stability of the resulting complex, enhancing the accuracy of spectroscopic measurements. The proposed method was successfully applied to the quantification of methyldopa in pharmaceutical formulations (tablets) from various sources, achieving recovery rates of up to 100%, reflecting high precision and selectivity. The values of the LOD (0.495 μg/mL) and LOQ (1.5 μg/mL) demonstrate the high sensitivity of the analytical method used. The fact that these values fall below the approved linear range confirms that the laboratory measurements were performed in a safe area and far from the analytical error limits. The study concludes that this method is a reliable, economical, and suitable analytical tool for quality control and routine pharmaceutical analysis.