One-Minute Electrochemical Enzymic Assay for Cholesterol in Biological Materials

In this rapid and specific micro-scale electrochemical enzymic assay for cholesterol and cholesterol esters, 10 tL of standard or sample is injected directly into a heated (50 #{176}C)thermostated, oxystated cuvet containing pH 7.25 buffer, cholesterol oxidase (EC 1.1.3.6), and cholesterol esterase (EC 3.1.1.13). The cholesterol esters are hy-drolyzed by the esterase, and the cholesterol is simulta-neously oxidized by the oxidase. The hydrogen peroxide produced from oxidation of the unesterified cholesterol is measured by a polarographic anode covered with an ac-etate/polycarbonate membrane. The membrane allows hydrogen peroxide to diffuse to the platinum anode, where it is oxidized, but prevents the diffusion of ascorbic acid, uric acid, and bilirubin to the electroactive surface. Tur-bidity does not interfere. The correlation (i) between result