A novel bioanalytical method based on UHPLC-HRMS/MS for the quantification of oleuropein in human serum. Application to a pharmacokinetic study

A highly sensitive, rapid and specific ultrahigh‐performance liquid chromatography, coupled to negative electrospray ionization high‐resolution tandem mass spectrometry, method was developed and validated in order to investigate the absorption of dietary oleuropein (OE) in human subjects. Serum samples were collected at predefined time points, after oral administration of an olive leaf extract enriched in OE (204.4 mg OE per capsule) to two subjects. Subsequently, samples were analyzed by the developed method after a simple solid‐phase extraction step. Chromatographic separation was operated with aqueous formic acid, 0.1% (v/v), and acetonitrile following a gradient program at a flow rate of 0.45 mL/min in an RP‐C18 (50 × 2.1 mm, 1.9 μm) column with a total run time of 2.7 min. The method was validated and successfully applied to the determination of OE in human serum, with the pharmacokinetic analysis of the data revealing a biphasic response.