Composition of the surface wax from tomatoes - I. Identification of the components by GC/MS

From the skins of tomatoes (Lycopersicon esculentum), the surface wax was rinsed with a tert-butylmethyl ether (TBME)/methanol (9+1) mixture. The wax components were separated into three fractions by elution from a small silica gel column. Toluene/hexane (2+1) eluted n-alkanes (C-21-C-35), iso- and anteiso-alkanes, n-alkadienes and -trienes (C-33, C-34 and C-35) as well as some aldehydes. Elution with hexane/TBME (3+1) yielded n-alkanols (C-18-C-34), n-alkadienols and alkatrienols (C-22, C-24 and C-26), small amounts of alkanoic acids (C-18-C-34) as well as sterols and triterpenols. Among the latter were identified: stigmasterol, beta-sitosterol, alpha-, beta- and delta-amyrin, taraxerol, taraxasterol, psi-taraxasterol, lupeol, multiflorenol, cycloartenol, germanicol and bauerenol. Final elution with TBME/methanol (9+1) resulted only in naringenin-chalcone, accompanied by small amounts of naringenin as an artifact formed during sample preparation. All components in those three fractions were identified by mass spectrometric analysis of the initial gas-chromatographic peaks or of peaks obtained from suitable derivatives.