Collision-induced dissociation mass spectra of glucosinolate anions

Collision-induced dissociation (CID) mass spectra of differently substituted glucosinolates were investigated under negative-ion mode. Data obtained from several glucosinolates and their isotopologues (S-34 and H-2) revealed that many peaks observed are independent of the nature of the substituent group. For example, all investigated glucosinolate anions fragment to produce a product ion observed at m/z 195 for the thioglucose anion, which further dissociates via an ion/neutral complex to give two peaks at m/z 75 and 119. The other product ions observed at m/z 80, 96 and 97 are characteristic for the sulfate moiety. The peaks at m/z 259 and 275 have been attributed previously to glucose 1-sulfate anion and 1-thioglucose 2-sulfate anion, respectively. However, based on our tandem mass spectrometric experiments, we propose that the peak at m/z 275 represents the glucose 1-thiosulfate anion. In addition to the common peaks, the spectrum of phenyl glucosinolate (beta-D-Glucopyranose, 1-thio-, 1-[N-(sulfooxy)benzenecarboximidate] shows a substituent-group-specific peak at m/z 152 for C6H5-C(=NOH)S-, the CID spectrum of which was indistinguishable from that of the anion of synthetic benzothiohydroxamic acid. Similarly, the m/z 201 peak in the spectrum of phenyl glucosinolate was attributed to C6H5-C(=S)OSO2-. Copyright (C) 2009 John Wiley & Sons, Ltd.