Streamlined LC-HRMS-based determination of sterols and triterpenic alcohols in edible oils for authentication...

Sterol analysis is a key parameter for assessing the authenticity and quality of olive oil, as defined by official methods. Nevertheless, these protocols are labor-intensive and require multiple preparation steps, including sample fractionation and derivatization. In the present work, a simplified analytical methodology is proposed for the determination of free sterols and triterpenic alcohols, eliminating these time-consuming procedures. The method is based on the direct analysis of saponified extracts, prepared according to the official protocol, followed by a single dilution step and analysis by liquid chromatography coupled to high-resolution mass spectrometry with electrospray ionization (LC-ESI-HRMS). To enhance the ionization efficiency of free sterols, which exhibit low response under conventional ESI conditions due to their non-polar nature, ammonium formate was added to the mobile phase. The analytical performance of the method was evaluated in terms of linearity, reproducibility, and limits of quantification to support its suitability for comparative fingerprinting analysis. Based on the obtained sterol profiles, several compounds were identified as potential markers for differentiating edible oils, including extra virgin olive oil, pomace olive oil, rapeseed oil, avocado oil, almond oil, and sunflower oil. The application of principal component analysis (PCA) to these data further enabled the distinction of extra virgin olive oil from the remaining vegetable oils, demonstrating the discriminatory potential of the proposed approach for oil characterization and classification.