The determination of cholesterol in serum by persulphuric acid oxidation.

A method for the determination of total cholesterol in serum is described. Optimum conditions are found for the isolation of the steroid free from extraneous chromogens, and a new sensitive colour reagent is introduced. The procedure is convenient for routine application, the final colour being light-stable and reasonably time-stable at room temperature. Comparisons are made with one other method and with another colour reagent. It is concluded that, for accurate results, treatment of the serum with alcoholic alkali followed by extraction with a hydrophobic solvent is essential. The choice of the colour-developing reagent is then no longer dependent on specificity for cholesterol, but becomes inter alia a matter of ease of operation, and of sensitivity, stability, and reproducibility of the final colour. These points are discussed in relation to other methods.