A green UV - Visible spectrophotometric method for quantitative determination of quercetin in methanolic Costus...

Quercetin, a naturally occurring flavonoid with high antioxidant and antidiabetic activity, necessitates efficient and environmentally friendly analytical techniques for regular quality control in herbal products. The current research presents the development and validation of an easy, accurate, and eco-friendly UV spectrophotometric method for the estimation of quercetin in the methanolic extract of Costus pictus. Methanol was chosen as the solvent based on its excellent solubility for quercetin. The maximum absorbance was identified at 370nm, and calibration was performed in the range of 2-18μg mL^-1, yielding an excellent correlation coefficient (R²=0.9983). The developed method was validated in accordance with ICH Q2(R2) requirements, confirming its specificity, accuracy (100±2%), precision (<2% RSD), and robustness. The detection limit was 0.045μg/mL, and the limit of quantification was 0.137μg/mL which further demonstrates the sensitivity of the method. AGREE and complex GAPI assessments confirmed high environmental compliance, driven by the use of low-toxicity solvents and reduced energy usage. The method was found to be stable for four hours and was also not affected by frequent excipients, which makes it ideal for repetitive analysis of herbal medicines and pharmaceutical formulations. This validated UV spectrophotometric method is a cost-saving, reproducible, and environmentally friendly alternative to standard chromatographic methods for quantitative analysis of quercetin in methanolic extracts of Costus pictus, facilitating both quality control and green chemistry.