Evaporative Light-Scattering Analysis of Sulforaphane in Broccoli Samples:Quality of Broccoli Products Regarding Sulforaphane Contents

摘要

Broccoli sulforaphane has received attention as a possible anticarcinogen.Sulforaphane analysis is difficult due to the lack of a chromophore for spectrometric detection.Hence,we developed a method for determining sulforaphane by using high-performance liquid chromatography(HPLC)coupled with an evaporative light-scattering detector(ELSD).Sulforaphane was extracted from acid-hydrolyzed broccoli samples,followed by solid-phase extraction and reversed-phase HPLC.Sulforaphane was detected by ELSD and concurrently identified by electrospray ionization time-of-flight mass spectrometry.The recovery of sulforaphane from broccoli samples was above 95%.The detection limit was 0.5 mug.The present method was sensitive enough to determine sulforaphane in mature broccoli,broccoli sprouts,and commercial broccoli products.Sulforaphane concentration in broccoli sprout(1153 mg/100 g dry weight)was about 10 times higher than that of mature broccoli(44-171 mg/100 g dry weight).Therefore,the broccoli sprout is recommended as a source of sulforaphane-rich products.In contrast,we found that sulforaphane could not be detected in most of broccoli products,suggesting present commercial broccoli products having low quality.