Separation by solid phase extraction and quantification by reversed phase HPLC of sulforaphane in broccoli

The separation and quantification of sulforaphane [1-isothiocyanato-4-(methylsulfinyl)-butane] from the florets, stalks and leaves of broccoli is described. The procedure uses solvent extraction, followed by purification of extracts using solid phase extraction (SPE) and reverse phase HPLC analysis. The HPLC method is compared with a spectrophotometric assay. To obtain information about the usefulness of acid hydrolysis of glucosinolates, the florets were left to autolyze at room temperature or were treated with concentrated hydrochloric acid, then analysed. The method proves reliable and reproducible as regards both SPE purification and chromatographic determination. Quantities of sulforaphane were found in the florets, stalks and leaves. The highest content of sulforaphane (110 mu g g(-1)) was found in the leaves. (C) 1998 Elsevier Science Ltd. All rights reserved.