Characterization of wax esters, free fatty alcohols and free fatty acids of crude wax from sunflower seed oil refineries

The sunflower seed wax (10–12%) from oil refineries was purified through two steps, namely, extraction using solvents and precipitation with chilled acetone. Fatty esters, free fatty alcohols and free fatty acids were separated by thin-layer chromatography (TLC). The fractions of fatty esters and free fatty alcohols were separated and identified by gas chromatography (GC) using a Dexil-300 column and OV-101 column, respectively, at temperatures from 150–290 °C and were further confirmed by Gas chromatography–mass spectrometry (GC–MS), using a capillary silica column SPB™-1 coated with polydimethyl siloxane. Among the long chain fatty esters (C38–C54), comprised of one unit of fatty alcohol and one unit of fatty acid through an ester linkage, the major esters were C40–C44, of which C42 was predominant. These fatty esters, upon hydrolysis, followed by methylation and subsequent GC–MS analysis, showed the presence of C16–C30 fatty acids in the bound form, whereas methylation of native wax indicated the presence of C18–C30 fatty acids in the free form. Acetylation of hydrolysis product showed the presence of C18–C30 fatty alcohols in the bound form, where as acetylation of native wax indicated that the C18–C32 fatty alcohols were in the free form. n-Triacontanol (C30), a plant growth regulator, was found in both free and bound forms.