Determination of free cholesterol based on a novel flow-injection chemiluminescence method by immobilizing enzyme.

A novel flow injection chemiluminescence method is proposed for determination of cholesterol in this paper. The cholesterol oxidase was immobilized onto sol-gel and prepared as an enzymatic reaction column. The determination of cholesterol was performed by quantitative determination of hydrogen peroxide produced from an enzymatic reaction. The luminol-H2O2-metal chelate diperiodatocuprate(III) system ensured that the method was highly sensitive and selective. Free cholesterol was determined over the range 5.0 x 10(-8) mol/L-5.0 x 10(-7) mol/L, with a limit of detection (3sigma) of 1.9 x 10(-8) mol/L. The relative standard deviation (RSD) for 2.5 x 10(-7) mol/L was 2.7% (n = 7). The proposed method offered the advantages of sensitivity, selectivity, simplicity and rapidity for free cholesterol determination, and was successfully applied to the direct determination of free cholesterol in serum.