Automated reaction-rate method for the direct determination of total serum cholesterol by use of the "CentrifiChem" parallel fast analyzer.

The direct procedure for determining serum cholesterol described by Wybenga et al. [C/in. Chem. 16, 980 (1970)] can be used to assay 29 samples in 10-mm reaction time by using the “CentrifiChem” parallel fast analyzer (Union Carbide). Commercial reference serum was used for standardization. Correlation of results with those obtained by the method of Abell et al. [J. Bio/. Chem. 195, 357 (1952)] for 54 samples yielded a regression line with a slope (m) of 0.897 and a y-intercept (b) of 231 mg/liter; the correlation coefficient (r) was 0.971. Compared with the manual procedure of Parekh and Jung [Anal. Chem. 42, 1423 (1970)] for 146 samples, the corresponding values were m = 0.991, b = 27 mg/ liter, and r = 0.981. Compared to serum extracts assayed with the “AutoAnalyzer” (Standard Technicon Methodology N-24a), 186 samples gave corresponding values of m = 0.990, b = 92 mg/liter, and r = 0.979. No bias significant at the 95% confidence level existed versus any of the three methods. Sera containing abnormally high bilirubin concentrations (>50 mg/liter) or abnormally high triglyceride content (>5,000 mg/liter) did not give significantly different cholesterol values on the CentrifiChem as compared with values obtained with either the AutoAnalyzer or the Parekh and Jung method.