An Improved Automated Determination of Serum Total Cholesterol with a Single Color Reagent

Abstract

An anhydrous color reagent containing ferric chloride is pumped through Tygon tubing to a glass coil in a 95° heating bath. Manually prepared serum extracts (1:20 isopropanol dilution) are presented to the stream of preheated color reagent, and the two are passed through three mixing coils, connected in series. The absorbance of the resultant color is determined at 550 mµ in a 15 mm. tubular flow-cell. The improved N-automated procedure gave values of greater precision (5.6%) for total cholesterol determined in replicate samples from sera pools than the N-automated procedure which lacked precision (27.7%). The values found in 60 individual serums are within 6.0% of total cholesterol values determined by the Abell et al. method.