A validated UV spectrophotometric method for simultaneous determination of ascorbic acid and resveratrol using isosbestic point approach.

A simple, precise UV-spectroscopy method using isosbestic point detection was developed for simultaneous analysis. The developed method exhibited good linearity over the concentration range of 0-12 μg/mL at both 269.7 nm and 252 nm. At 269.7 nm, the R2 values were 0.9963 and 0.9964 for ascorbic acid and resveratrol, with LOD/LOQ values of 1.597/4.838 μg/mL and 1.563/4.737 μg/mL, respectively. At 252 nm, the corresponding R2 values were 0.9922 and 0.9995, while the LOD/LOQ values were 2.537/7.688 μg/mL for ascorbic acid and 0.584/1.771 μg/mL for resveratrol. Percentage recovery rates of 50%, 100%, and 150% ranged from 98.6% to 100.6%, 98.5% to 100.4%, and 100.1% to 99.9%, respectively, with low %RSD values. %RSD of ascorbic acid and resveratrol combination, obtained during intra-day analysis, was 0.866% at λ1 and 0.486% at λ2. Inter-day test revealed a %RSD of 0.976% at λ1 and 0.664% at λ2, while repeatability was measured at 0.879 for λ1 and 0.411 for λ2, respectively. The developed UV method was simple, precise, and accurate for quantifying ascorbic acid and resveratrol in pure drugs in methanolic solution.