Direct determination of the linoleate/oleate ratio in serum cholesterol esters by liquid chromatography
Bernert, J.T.; Akins, J.R.; Miller, D.T.
Clinical Chemistry 28(4 Pt 1): 676-680
1982
ISSN/ISBN: 0009-9147 PMID: 7074839 Document Number: 191920
A convenient method is described for the direct determination of the serum cholesterol linoleate/cholesterol oleate (L/O) ratio by reversed-phase high-performance liquid chromatography. After removal of phospholipids by silicic acid chromatography, a serum extract is analyzed on a 5-.mu.m particle size Ultrasphere-ODS column, eluted isocratically with acetonitrile/isopropanol (30/70, by vol). Detection is at 200 nm. Cholesterol palmitoleate interferes with the measurement when the analysis is based on peak area, but not when peak height is used. The overall precision of L/O measurements by this method was very similar to that observed with a GLC procedure, in which the cholesterol esters are first isolated and transesterified to the methyl esters. In both cases, the within-run CV for 6 replicate analyses was less than 2%. Analysis of 53 human serum samples by both methods yielded very similar L/O ratios. A plot of the data (this method = y) vs. the usual GLC procedure gave a correlation coefficient of 0.988 and a regression equation of y = 1.03x + 0.013. Furthermore, direct analysis of serum cholesterol ester L/O ratios by this liquid-chromatographic method is simpler, quicker, and more readily adaptable to automation.