Development and validation of a LC-MS/MS method to determine sulforaphane in honey

A new method was developed to determine sulforaphane (SFN) in honey using liquid chromatography tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). An efficient extraction procedure was proposed (average analyte recoveries were between 92% and 99%); this involved a solid phase extraction (SPE) with a polymeric sorbent. Chromatography was performed on a Synergi™ Hydro analytical column with a mobile phase of 0.02 M ammonium formate in water and acetonitrile, at a flow rate of 0.5 mL/min. The method was fully validated in terms of selectivity, limits of detection (LOD) and quantification (LOQ), linearity, carry-over effect, reinjection reproducibility, precision and accuracy. The LOD and LOQ values were below 0.8 μg/kg and 2.6 μg/kg, respectively. The proposed method was applied to analyze SFN in honey from different botanical origins (rosemary, multifloral, orange blossom and heather), and SFN was detected at trace levels in some of the honey samples examined.