Quantification and Determination of Composition of Steryl Ferulates in Refined Rice Bran Oils Using an UPLC-MS Method

Gamma-oryzanol contains a mixture of steryl ferulates found in rice bran oil. Several studies have attributed nutraceutical properties to this mixture, such as hypocholesterolemic and anti-inflammatory activities. A method based on ultra-performance liquid chromatography coupled with electrospray ionization mass spectrometry was developed and evaluated for the simultaneous quantification of gamma-oryzanol and identification of five major steryl ferulates directly in refined rice bran oils (RBO) samples. The proposed method was evaluated according to linearity by obtaining standard curves with R ² values above 0.990, and limit of detection values ranged from 1.9 to 5.9 µg/mL, whereas limits of quantification ranged from 5.9 to 17.9 µg/mL; inter- and intraday accuracy and precision were within the range required by the US Food and Drug Administration guidelines; recovery levels ranged from 78 to 85% for gamma-oryzanol, and from 84 to 119% for steryl ferulates. The method can be considered robust in relation to the NH₄OH (ammonium hydroxide) content and cone voltage variations, with coefficient of variation and average relative percentage deviation values lower than 7.0 and 4.4%, respectively. The stability during the storage test was maintained in concentrated samples (18.5 µg/mL), with recovered values between 93 and 113%. This method was successfully applied to the analysis of RBO samples, demonstrating that it could be easily used for quality control purposes.