Abstract:The influences of three factors on determination of gibberellic acid by HPLC, such as volume fraction of methanol,pH of mobile phase and wavelength,were compared by investigating the retention time,peak shape,standard deviation, resolution, tailing factor and linear related coefficient.The data indicated that the appropriate HPLC condition for gibberellic acid was as follows:C18 column(250mmx4.6mm,5.0um), sample load 20 μl,mobile phase 35% methanol(pH 4.0),flow rate 1.0mL/min,column temperature 25¡æ and UV wavelength 210 nm.The evaluation results showed that the mean recovrey was 99.52% and 99.44% for 0.2ug/mL gibberellic acid,and the RSD was 1.05% and 0.90%, respectively under the HPLC condition.Different mass concentrations of gibberellic acid standard solution were tesetd 5 times repeatedly,the RSD of peak area was 0.37% and 0.13% for 10 μg/mL and 50 μg/mL gibberellic acid.The HPLC method for determining gebberellic acid in soybean was proved to be sensitive and accurate.