GC-MS method for determination of sulforaphane

A method for quantitative determination of sulforaphane based on GC-MS and deuterium-labeled sulforaphane as internal standard has recently been developed by Lipidox.

As an application, sulforaphane was determined in seedlings of broccoli, a well-established source of glucoraphanin and sulforaphane. Thus, broccoli seeds were germinated at 22C under a 16h/8h light-dark cycle. Seedlings (0.5-1.5 g) were harvested at days 3-8 and placed on Dry Ice. Weighed frozen seedlings were added to 10 mL of ethanol containing d8-sulforaphane (14.1 mg) and homogenized for 5 min at 0C using an Ultra-Turrax operated at maximum speed. The supernatant obtained after centrifugation was taken to dryness, and the residue subjected to solid-phase extraction using a Supelclean LC-CN cartridge. Material eluted with ethyl acetate-ethanol (1:1, v/v) was subjected to GC-MS with selected monitoring of the ions m/z 160 (unlabeled sulforaphane) and 167 (d8-sulforaphane) (Fig. 1). In agreement with previous work, a burst of sulforaphane (about 85 mg seedling fresh weight) was observed (Fig. 2).





Fig. 1. GC-MS analysis of sulforaphane in seedlings of broccoli (upper, day 3 of germination; lower, day 4 of germination). The ions m/z 160 (unlabeled sulforaphane) and 167 (d8-sulforphane) were monitored and the peak areas integrated.
A capillary column of 5% phenylmethylsilicone (12 m, 0.33 mm film thickness) was used with helium as the carrier gas. The temperature was raised from 80C to 300C at a rate of 10C/min.

Fig. 2. Levels of sulforaphane in seedlings of broccoli at days 3-8 of germination.