Cholesterol gas-liquid chromatographic microassay in serum lipoproteins separated by polyacrylamide gel electrophoresis

A new method of cholesterol assay in serum lipoprotein fractions separated by electrophoresis on polyacrylamide plates is described: each lipoprotein fraction was collected by cutting the gel and, after gel dissolution, cholesterol was extracted and assayed by gas-liquid chromatography. This method associates the specificity and sensitivity of gas-liquid chromatography with the resolution of polyacrylamide gel electrophoresis, a highly reliable technique for hyperlipoproteinemia phenotyping. It is precise (variation coefficient below 2%), fast and needs only 2.5 microlitres of serum. Direct assay of cholesterol is feasible not only on each of the three main fractions, very low density lipoproteins, low density lipoproteins and high density lipoproteins, but also on intermediary fractions such as Lp(a) lipoprotein. This method should allow a better evaluation of the relationship between the serum cholesterol fractions and development of atherosclerosis.