Development of an ultrasound assisted method for determination of phytosterols in vegetable oil

The aims of this study were the optimization and validation of a new ultrasound assisted phytosterol method through analysis of response surface generated from Box-Behnken design. Variables quantity of sample (g), volume of KOH/MeOH (mL) and ultrasound time (s) were investigated in three levels. The evaluation process of the methodology was executed through determination of analytical parameters, such as selectivity, linearity, accuracy, dynamic linear range, "intra-day" accuracy and limits of detection and quantification. Optimized conditions for stigmasterol determination were 0.25 g; 2.5 mL; 300 s; and beta-sitosterol were 0.25 g; 5.4 mL; 300 s. The evaluated conditions and all investigated analytical parameters showed that the method is effective for determination of analytes beta-sitosterol and stigmasterol. This new analytical method has the same efficiency of the traditional method, while significantly reducing the total time of extraction for 300 s regarding saponification step when compared to 3600 s from the traditional method.