Development and validation of a specific method to quantify intact glucosinolates in honey by LC–MS/MS

Abstract

Glucosinolates (GLSs), which are secondary plant metabolites, have been scarcely investigated in honey. Recently, research has been conducted into the potential of GLSs as botanical biomarkers or as a parameter to establish honey freshness, but the employed methodologies were not specifically developed for intact GLSs quantification in honey. The aim of this study was to develop a new method to quantify twelve intact GLSs in honey, by using liquid chromatography with tandem mass spectrometry. An efficient extraction procedure was proposed; this involved dissolution of the honey with heated water, followed by solid-phase extraction with a weak anion exchange sorbent. Chromatography was performed on a C18 analytical column with a mobile phase of formic acid in water (0.5%, v/v) and formic acid in acetonitrile (0.5%, v/v). 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 4μgkg−1 and 10μgkg−1, respectively. The proposed method was applied to analyze intact-GLSs in honey from different botanical origins. Four of the intact GLSs studied were identified at low concentration levels (<25μgkg−1) in several of the samples analyzed.