A rapid, quantitative determination of total and free cholesterol with anthrone reagent

Abstract

A simple, rapid microcolorimetric determination for total and free 3β-hydroxy sterols in serum and tissues has been described. Following extraction of total sterols and saponification of the esterified fraction by established procedures, the sterol is precipitated in 15 min at 45°C as the digitonide using 10% aluminum chloride. The isolated sterol digitonide is purified by twice recrystallizing from methanol-10% aluminum chloride (1 : 1), each step requiring 20 min at 45°C. The precipitate is washed with acetone and suspended in glacial acetic acid, and the digitonin moiety is determined with a stable anthrone reagent. Multiple analyses of sterol concentrations as low as 15–20 μg are routinely determined with an accuracy comparable to the method of Sperry and Webb, and with a greater sensitivity and precision than obtained with the latter method.