Precipitation methods for quantification of lipoproteins.

In the foregoing discussion we have included precipitation methods for HDL analysis that we consider to be among the most accurate and extensively characterized compared to analyses performed with the ultracentrifuge. The emphasis has been on the precipitation steps rather than on the analysis of cholesterol in the lipoprotein fractions. It is evident, however, that the accuracy of the cholesterol method itself will influence the overall reliability of the measurements even when the lipoprotein fraction has been separated adequately. Ideally, the cholesterol measurements would be made with reference methods. Since this is usually not practical with large numbers of samples, the accuracy and precision of the method employed should be established with respect to a reference method, such as that of Abell et al., before being used for routine cholesterol measurements. Finally, it should be mentioned that the conditions used in the methods discussed here were developed for human plasma or serum, and in the authors' experience may have to be modified for the adequate separation of plasma lipoproteins in other species.