Web Release Date: March 4,
Evaporative Light-Scattering Analysis of Sulforaphane in Broccoli Samples: Quality of Broccoli Products Regarding Sulforaphane Contents
and
Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan, and Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-0195, Japan
Received for review July 27, 2005. Revised manuscript received February 2, 2006. Accepted February 2, 2006.
Abstract:
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 
g. 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.
Keywords: Broccoli; broccoli sprouts; evaporative light-scattering detector (ELSD); sulforaphane
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