Determination of glucosinolates in traditional Chinese herbs by high-performance liquid chromatography and electrospray ionization mass spectrometry.

A reversed-phase HPLC method has been developed for determination of twelve intact glucosinolates--glucoiberin, glucocheirolin, progoitrin, sinigrin, epiprogoitrin, glucoraphenin, sinalbin, gluconapin, glucosibarin, glucotropaeolin, glucoerucin, and gluconasturtiin--in ten traditional Chinese plants. The samples were extracted with methanol and the extracts were cleaned on an activated Florisil column. A mobile phase gradient prepared from methanol and 30 mmol L(-1) ammonium acetate at pH 5.0 enabled baseline separation of the glucosinolates. Glucosinolate detection was confirmed by quadrupole time-of-flight tandem mass spectrometric analysis in negative-ionization mode. Detection limits ranged from 0.06 to 0.36 microg g(-1) when 5 g of dried plant was analyzed. Recoveries of the glucosinolates were better than 85% and precision (relative standard derivation, n = 3) ranged from 5.3 to 14.6%. Analysis of the glucosinolates provided scientific evidence enabling differentiation of three pairs of easily confused plants.