Determination of glucosinolate profiles in Chinese vegetables by precursor ion scan and multiple reaction monitoring scan mode (LC-MS/MS)

Abstract

Liquid chromatography-electrospray ionization (ESI) mass spectrometry was used to describe the glucosinolate (GSL) profiles in three Chinese vegetables. The strategy was based on first screening for possible glucosinolates via precursor ion scan mode (PreIS). Further validating was done using the multiple reaction monitoring scan mode (MRM). The obtained fragment ions [S=C=NOH]− for m/z 75 and [SO4H]− for m/z 97 were used in both scan modes to reveal the masses of the GSL precursor ions [M-H]− which were further validated by the mostly known chromatographic behavior of the resulting intact GSL. The feasibility of the strategy was first demonstrated using crude extracts of broccoli. The tandem mass spectrometric experiments in negative ion ESI proved to be sensitive and selective enough to rapidly examine the GSL profiles even of crude plant extracts. The results adequately characterize the target differences between various GSL distributions in vegetables induced by treatment of methyl jasmonate.