Quantitative determination of glucoraphanin in Brassica vegetables by micellar electrokinetic capillary chromatography

Glucoraphanin, a glucosinolate, is found naturally in plants and is present in relatively high concentrations in broccoli. Glucosinolates have received much attention as studies have indicated that a diet rich in them may provide some protection from certain cancers. A micellar electrokinetic chromatography (MEKC) method using sodium cholate as the micellar phase has been developed to quantify for glucoraphanin in broccoli (seeds and florets) and Brussels sprouts. The glucoraphanin peak elutes just under 5 min with a theoretical plate number of 380,000 per metre of capillary. The method is suitable for crude extracts of broccoli and Brussels sprouts. Glucoraphanin in broccoli seeds (1330 mg/100 g) broccoli florets (89 mg/100 g) and Brussels sprouts (3 mg/100 g) was determined and agreed with the data obtained by high performance liquid chromatography. The LODs were 10–100 times below the levels typically found in broccoli seeds (4 mg/100 g), broccoli florets (0.9 mg/100 g) and Brussels sprouts (0.1 mg/100 g).