3.3.1. Standard solutions
Calibration curve for AA was obtained by plotting the AA peak area against the AA concentration at 10 levels. The response of AA over a concentration range of 0.5–200 mg L−1 was linear (Y=60.384x+1.437) with a regression coefficient (R2) of 0.997.
The limit of quantitation (LOQ) and detection (LOD) were 0.20 and 0.05 mg L−1, respectively, which was taken as the amount of ascorbic acid giving a signal-to-noise ratio greater than 3. The RSD values for repeatability and intra-day reproducibility (n=6) for a standard solution containing 25 mg L−1 of AA were 1.24% and 7.20%, respectively. For study of intra-day reproducibility the standard solution was kept at 4 °C and in the dark.