Identification and quantification of glucosinolates in rapeseed using liquid chromatography–ion trap mass spectrometry

Abstract

A rapid and sensitive method for the speciation and quantification of glucosinolates in rapeseed is described. The method combines liquid chromatography (LC) with ion trap mass spectrometry (ITMS) detection. Electrospray ionization (ESI) has been chosen as the ionization technique for the on-line coupling of LC with ITMS. Glucosinolates are extracted from different rapeseeds with MeOH and the extracts are cleaned-up by solid phase extraction with Florisil cartridges. Aqueous extracts are injected into LC system coupled to an ITMS, leading to accurately quantify eight of the most important glucosinolates in rapeseed, by MS2 mode and confirming their structure by MS3 acquisition. All the glucosinolates found in rapeseeds provide good signals corresponding to the deprotonated precursor ion [M-H]-. The method is reliable and reproducible, and detection limits range from 0.5 nmol g(-1) to 3.7 nmol g(-1) when 200 mg of dried seeds of certified reference material are analyzed. Within-day and between-day RSD percentages range between 2.4-14.1% and 3.9-16.9%, respectively. The LC-ESI-ITMS-MS method described here allows for a rapid assessment of these metabolites in rapeseed without a desulfatation step. The overall process has been successfully applied to identify and quantify glucosinolates in rapeseed samples.

Analysis of Intact Glucosinolates in Beeswax by Liquid Chromatography Tandem Mass Spectrometry

“…Regarding the analysis of intact GLSs, solid-phase extraction has been successfully used to extract intact GLSs with other matrices, especially vegetables (Rochfort et al 2006;Sasaki et al 2012); similar results have been seen with pressurized liquid extraction (Alarcón-Flores et al 2013;Mohn et al 2007). Nevertheless, the preferable and simplest choice is a solvent extraction with heated water or mixtures of methanol and water (Ares et al 2014;Bell et al 2015;Domínguez-Perles et al 2010;Glauser et al 2012;López-Berenguer et al 2008;Millán et al 2009;Rochfort et al 2008). Consequently, taking into account our experience and the favorable results obtained in recent research (Ares et al 2015;Yáñez et al 2014), we decided to use solvent extraction as the sample treatment.…”

“…The MRM transition that provided the highest signal was used for quantification (see Table 1); meanwhile, a second MRM transition was used for confirmation (see Table 1). Such ions/transitions have been commonly used in the existing literature devoted to analyzing GLSs by MS/MS (Ares et al 2014;Bell et al 2015;Glauser et al 2012;Millán et al 2009;Rochfort et al 2008;Sasaki et al 2012). To ascertain how the matrix influenced the detection of GLSs, the peak areas of the GLSs in standard solutions were compared with those obtained in AF samples (beeswax samples spiked after sample treatment).…”

“…Intact GLSs were previously analyzed in negative ESI mode (Ares et al 2014;Bell et al 2015;Glauser et al 2012;Millán et al 2009;Rochfort et al 2008;Sasaki et al 2012), the best results being obtained in terms of peak area and peak height. Table 1) in full-scan spectra.…”

“…Consequently, taking into account our experience and the favorable results obtained in recent research (Ares et al 2015;Yáñez et al 2014), we decided to use solvent extraction as the sample treatment. Analysis of intact GLSs was usually performed by LC with ultraviolet or diode array (Ares et al 2014;Gratacós-Cubarsí et al 2010;López-Berenguer et al 2008;Rochfort et al 2006;Truchado et al 2010;) and mass spectrometry (MS) (Alarcón-Flores et al 2013;Ares et al 2014;Bell et al 2015;Domínguez-Perles et al 2010;Glauser et al 2012;López-Berenguer et al 2008;Millán et al 2009;Rochfort et al 2008;Sasaki et al 2012) detectors, while C 18 analytical columns were used in most cases. Among these, MS, and in particular tandem mass spectrometry (MS/MS), has emerged as one of the preferred detection techniques, providing as it does sufficient sensitivity and unambiguous identification and quantification of GLSs (Alarcón-Flores et al 2013).…”

Collision‐induced dissociation mass spectra of glucosinolate anions

“…Therefore, the use of more specific product ions would be more beneficial. [17] In order to properly identify more selective product ion(s) suitable for MRM quantification of glucosinolates, a better understanding of their fragmentation pathways is necessary.…”