Ferulic acidAdded (ng/ml) Stability Mean (ng/ml) SD RSD(%) RE (%) 5 5.05 0.20 4.0 1.0 500 432.54 1.81 0.4 -13.5 3000 3064.17 89.48 2.9 2.1

Ferulic acid standard solution at different concentrations of 5, 500 and 3,000 ng/ml in rat plasma was prepared. After post-treatment for 12 hours at 7°C, the samples were injected into UPLC-MS/MS to determine the stability of ferulic acid. Mean of the concentration (ng/ml) of ferulic acid in rat plasma, SD, RSD (%) and RE (%) was calculated, n = 3.

Table 6: Stability for the analysis of ferulic acid after post-treatment for 12 hours (7°C).