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Biocoulometry of cholesterol using porous carbon felt electrodes
Author(s) -
Uchiyama Shunichi,
Kato Shinichi,
Suzuki Shuichi,
Hamamoto Osamu
Publication year - 1991
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140030111
Subject(s) - cholesterol oxidase , hydrogen peroxide , chemistry , coulometry , electrolysis , electrolyte , cholesterol , inorganic chemistry , catalysis , carbon fibers , nuclear chemistry , chromatography , organic chemistry , electrode , biochemistry , electrochemistry , materials science , composite material , composite number
Free and total cholesterols in human serum have been determined by controlled‐potential coulometry with porous carbon felt electrodes. In such a coulometric cell, a small amount of sample solution was dropped on the carbon felt dipped into electrolyte containing enzymes and a mediator. Hydrogen peroxide is produced by the enzymatic reaction of cholesterol catalyzed by cholesterol oxidase, and the complete electroreduction of hexacyanoferrate(III) ions [produced by the reaction of hexacynoferrate(II) ions and hydrogen peroxide catalyzed by peroxidase] was carried out under controlled‐potential conditions. In the case of determining total cholesterol in human serum, cholesterol esters were converted to free cholesterol by cholesterol esterase reaction prior to the addition of the sample solution into electrolyte. The conversion ratios of free cholesterol to hydrogen peroxide were found to be 85–89% (RSD < 6%). The electrolysis time of one sample was less than 5 minutes. Immobilization of cholesterol oxidase to the carbon felt surface was attempted; the activity of cholesterol oxidase, Immobilized by the diazo‐coupling method began to decrease 3 days after the immobilization.