MICRODETERMINATION OF MAJOR INDIVIDUAL ISOTHIOCYANATES AND OXAZOLIDINETHIONE IN RAPESEED

A method was developed for the quantitative determination of the major individual thioglucosides (as their aglycones) in rapeseed on a micro scale. The thioglucosides in the meal were hydrolyzed with myrosinase (E.C. 3.2.3.1, thiogluco-side glucohydrolase [from white mustard seed]), and the released aglycones were extracted with methylene chloride. The 3-butenyl and 4-pentenyl isothiocyanates were determined by gas-liquid chromatography. The 5-vinyl-2-oxazolidinethione was determined on an aliquot of the same extract by UV absorption. Five to 20 mg of seed or meal were used, and one operator could analyze 24 samples per day. The standard deviation was [plus or minus] 3% for the isothiocyanates and [plus or minus] 6% for the oxazolidinethione. The limit of detection was 0.1 mg per gram of meal for the isothiocyanates and 0.3 mg per gram of meal for the oxazolidinethione. Small amounts of phenylethyl isothiocyanate and 2 unidentified isothiocyanates were also found.