The Chemical Differentiation between Sinapis arvensis and Brassica napus Seeds by Surface Wax Analysis

The hydrocarbons were extracted and isolated from the surface of both Sinapis arvensis and Brassica napus seeds. The major hydrocarbon of the weed seed was found to be hentriacontane (C₃₁H₆₄) whereas nonacosane (C₂₉H₆₀) was the predominant hydrocarbon in rapeseed. This can be used as a criterion upon which differentiation can be made. Total “wax” extracts of the two seed types were analysed by gas chromatography. The waxy material extracted from the weed seed was found to have a major peak at 3320 Kovats retention indices which was absent in all rapeseed varieties. By studying a series of known composites of rapeseed and wild mustard, the level of wild mustard contamination could be accurately determined down to a level of 1 % using a ratio of two peaks at 2900 and 3320 Kovats retention indices.