VLDL apolipoprotein B determination in blood serum following precipitation of LDL with polyvinylsulphate.

A method is described for the determination of VLDL apolipoprotein B by radial immunodiffusion (RID) in serum supernatants following precipitation of LDL with polyvinylsulphate. The measurement of VLDL apolipoprotein B is based on the incubation of the polyvinylsulphate supernatant with triglyceride lipase (330 kU/l end concentration) for 12-24 hours at 37 degrees C. A good measure of agreement was found for the corresponding VLDL apolipoprotein B values measured by RID in the polyvinylsulphate supernatants (y) and VLDL apolipoprotein B values calculated as tetramethylurea-insoluble protein in the d less than 1.006 kg/l serum fraction (x) (r = 0.88, y = 0.96x + 0.004, n = 54). Within the tested range of 1.2 mmol/l to 6.7 mmol/l triglycerides, the concentration of apolipoprotein B measured in the polyvinylsulphate supernatant showed a linear relationship. Correlation analysis of VLDL apolipoprotein B values and serum triglycerides and VLDL cholesterol, respectively, showed a good correlation (r = 0.77 and r = 0.75, respectively, n = 54). In the determination of VLDL apolipoprotein B measured in polyvinylsulphate supernatant, a variation coefficient of 4.3% (means = 10.1 mmol/l, n = 20) was found in relation to the precision in the series, and a variation coefficient of 11.4% (means = 5.3 mmol/l, n = 15) in relation to day to day precision.