Quantitation of Long Chain Fatty Acids as the Methoxyphenacyl Esters

Abstract

In recent years High Performance Liquid Chromatography [HPLC] was used for the separation of long chain fatty acids. A procedure for the quantitation of the major fatty acids found in oral bacteria was established. The acids studied were C-10, C-12, C-14, C-16, C-18, C-18:1, C-20 and C-22. The samples were esterified with .alpha.-bromo-m-methoxyacetophenone, separated by reversed phase chromatography and monitored at both 254nm and 280nm. The fatty acids have approximately the same linear absorbance range at 254nm from 100 pmol-50 nmol. While the linear absorbance range was similar, the response factors varied by more than 40% when using peak heights, compared to less than a 15% variation when using peak areas. Several A-NHl fatty acid reference mixtures were used to assure the reliability (average relative error = 3.72%) of the method. Subsequent analysis of a bacteria sample was made by both HPLC and GLC to further substantiate the validity of the technique.