AMPEROMETRIC ENZYMATIC DETERMINATION OF TOTAL CHOLESTEROL IN HUMAN-SERUM WITH TUBULAR CARBON ELECTRODES

An amperometric enzymatic assay for total cholesterol in human serum has been developed. The assay utilizes cholesterol esterase, cholesterol oxidase, and peroxidase. H2O2 produced by the oxidase is coupled via peroxidase to produce K3Fe(CN)6 which is measured at a tubular carbon electrode. The reactions go all the way to completion and the K3Fe(CN)6 formed can be stoichiometrically related to total cholesterol concentration. Therefore, the assay can be calibrated with standard K3Fe(CN)6. (The reaction time is minimized by running the esterase reaction at 60 C.) The method shows very good reproducibility, accuracy, and sensitivity. Bilirubin and hemoglobin show no interference and ascorbic acid up to 4 mg/dL did not interfere with the assay. Results obtained by the amperometric method show excellent agreement (correlation coefficient = 0.995) with those obtained by the Leffler method. © 1979, American Chemical Society. All rights reserved.