Optimization of acid hydrolysis conditions for total isoflavones analysis in soybean hypocotyls by using RSM

The optimum hydrolysis conditions of soybean hypocotyls with HCl for a quantitative HPLC determination of total isoflavones (TI) were studied by using response surface methodology (RSM). HCl concentration (HC), hydrolysis time (HT) and reaction temperature (RT) were assumed to be the most important factors affecting hydrolysis for the determination of TI. Optimum hydrolysis conditions for maximizing the determination of TI were: HC=3.42N, HT=205.5 min and RT=44.6°C. The model had a satisfactory coefficient of R2 (=0.967) and was verified experimentally. Furthermore, the recovery of individual isoflavones was 97–100% under the optimum hydrolysis conditions. The results suggested that the conditions were mild and useful for maximizing a quantitative HPLC determination of TI in soybean hypocotyls.