Gas Chromatography/Mass Spectrometry Method for the Determination of Sulforaphane and Sulforaphane Nitrile in Broccoli

Phytochemicals, especially the secondary metabolites synthesized by plants, play key roles in human nutrition, health, wellness, and disease prevention. Some phytochemicals may be harmful to human health. For example, two closely related 4-methylsulfinylbutyl glucosinolate [glucoraphanin] hydrolysis products from broccoli (Brassica oleracea L. var. Botrytis), 1-isothiocyanato-4-(methylsulfinyl)butane (sulforaphane) and 5-(methylsulfinyl)pentanenitrile (sulforaphane nitrile), may have beneficial or deleterious effects on human health, respectively. Preliminary studies using a gas chromatography/mass spectrometry (GC/MS) system operated under split/splitless conditions revealed that ≈80% of sulforaphane was degraded to 3-butenyl isothiocyanate. A GC/MS method was developed wherein thermal degradation of sulforaphane was reduced to 5% through the use of an appropriate injector liner and precise control of the carrier gas flow rates. The method provides a simple, rapid technique for the analysis of both sulforaphane and sulforaphane nitrile that is suitable for routine screening of plant materials. Keywords: Sulforaphane; sulforaphane nitrile; GC/MS; isothiocyanate; Brassica oleracea; broccoli