Improved Separation of Intact Glucosinolates in Bee Pollen by Using Ultra-High-Performance Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry

Abstract

A method to determine 15 intact glucosinolates (epiprogoitrin; glucoalyssin; glucobrassicanapin; glucobrassicin; glucoerucin; glucoiberin; gluconapin; gluconasturtiin; glucoraphanin; glucotropaeolin; 4-hydroxyglucobrassicin; 4-methoxyglucobrassicin; neoglucobrassicin; progoitrin; sinigrin) in bee pollen has been proposed, by means of ultra-high liquid chromatography coupled to a quadrupole time-of-flight mass detector. Efficient sample treatment (with average analyte recoveries between 80 and 96%) involving a solid-liquid extraction with hot water, followed by solid-phase extraction with a weak anion exchange sorbent (NH2), was employed to analyze those intact glucosinolates in bee pollen. Chromatographic analysis (15 min) was performed on a fully porous silica–based column (Luna® Omega C18) with a mobile phase composed of a mixture of acetonitrile (0.1% formic acid) and water (0.1% formic acid) in gradient elution mode at a flow rate of 0.2 mL/min. Accordingly, the analytical performance of the proposed method was evaluated, and it was then applied to determine intact glucosinolates in commercial bee pollen samples from different Spanish regions. Ten intact glucosinolates were identified in certain samples over a wide concentration range.