Quantitative determination of intact glucosinolates in broccoli, broccoli sprouts, Brussels sprouts, and cauliflower by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry

Many methods have been proposed to analyze glucosinolates, a class of phytochemicals whose breakdown products are thought to be responsible for an improvement in health; however, few are quantitative and many are time consuming. A selective and sensitive quantitative method for direct determination of intact glucosinolates was developed using liquid chromatography coupled to electrospray ionization tandem mass spectrometry with selected reaction monitoring detection. Detection limits for glucoiberin, sinigrin, progoitrin, glucoerucin, and glucotropaeolin were 1.75, 1.38, 1.36, 0.6, and 0.63 pmol, respectively. Intraassay precision of the method was within 10% for each compound. The method was successfully applied to quantify 10 individual glucosinolates in broccoli, broccoli sprouts, Brussels sprouts, and cauliflower. The advantage of the proposed method includes analysis of individual intact glucosinolates rather than the conversion to desulfoglucosinolates, an increased selectivity through the use of mass spectrometry, and a 10-fold improvement in detection sensitivity over conventionally used HPLC techniques.