Advances in the analysis of natural waxes provided by thermally assisted hydrolysis and methylation (THM) in combination with GC/MS

THM-GC/MS was applied to the analysis of natural waxes (bleached beeswax, lanolin, yellow carnauba wax). By means of flash heating the wax samples in the presence of tetramethylammonium hydroxide (TMAH) as an alkaline derivatization reagent, the wax constituents, mainly high molecular weight esters, were hydrolyzed and converted into their methyl derivatives. Subsequent GC analysis of the methylation products resulted in chromatograms showing very specific signal patterns for each of the materials investigated. Mass spectrometric detection of the yielded methyl derivatives enabled the identification of more than ninety compounds present in the wax samples, i.e. fatty acids, hydroxy fatty acids, fatty alcohols, diols and sterols, respectively. Additionally to the analysis of real wax samples, several wax-relevant compounds (waxy esters, fatty acids, fatty alcohols) were studied with regard to their methylation behaviour. The investigations show that THM-GC/MS is able to overcome problems that arise from conventional Py-GC analysis of waxes, where thermal fragmentation can lead to rather non-specific pyrolysis products. Therefore, THM-GC/MS is an advantageous technique for the comprehensive analysis of natural waxes. (C) 1999 Elsevier Science B.V. All rights reserved.