Gas chromatographic determination of indole glucosinolates—a re‐examination

The use of gas‐liquid chromatography (g.l.c.) as a technique for the analysis of glucosinolates, including indole glucosinolates, in low‐glucosinolate rapeseed meal and seed was assessed. Variation contributed by various steps of g.l.c. methodology was studied, and following modifications to the method analytical results were compared with those estimated from thiocyanate ion (SCN) release following treatment of samples with myrosinase enzyme. The volume of water required to effectively elute glucosinolates from a DEAE Sephadex column was shown to cause variability in analytical results. The effect was dependent upon the internal standard used and was most pronounced for indole glucosinolates. Heat treatment (95°C) required in the procedure for the inactivation of myrosinase enzyme was shown to result in substantial decomposition of indole glucosinolates. In this regard a standard procedure involving 15 min dry heat treatment followed by 3 min wet heat treatment is recommended. With these modifications the g.l.c. methodology was shown to be adequate as a routine procedure for the analysis of glucosinolates in low‐glucosinolate rapeseed meal and seed.