Brigitte Draeger

Precipitation methods for the determination of LDL-cholesterol.

The selective precipitation of low-density lipoproteins (LDL) with polyvinyl sulfate (PVS), and the immunoprecipitation of high-density lipoproteins (HDL) and very-low-density lipoproteins (VLDL) with an anti-HDL antibody, can both be used to establish simple methods for the determination of LDL cholesterol. Whereas the PVS method requires the calculation of LDL cholesterol as the difference of total and supernatant cholesterol, the immunoprecipitation method allows the direct measurement of LDL cholesterol in the supernatant. As a first step, both methods were optimized to yield accurate values for normolipemic and slightly hyperlipemic serum samples. Moreover, the determination of LDL-cholesterol in lipemic sera can be achieved by a combination of immunoprecipitation and polyanion precipitation.

Fluorescence Polarisation Immunoassay

Since the introduction of radio immunoassay techniques [1], many different assay principles based on antibodies as specifiers have become routine tools in clinical diagnostics. Heterogeneous immunoassays, e.g. enzyme linked immunosorbant assays (ELISA) [2], require a series of time consuming incubation and wash steps, but they are characterized by a high sensitivity with a detection limit of 10−13 moll−1 and even lower.