Contact Info
Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf
Sample preparation
Citations 2
"Microwave-assisted Saponification Of Animal Greases For Cholesterol Determination"
Anal. Chim. Acta
1998 Volume 371, Issue 2-3 Pages 297-303
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After extraction with petroleum ether and dissolution of the unsaponifiables in toluene, total cholesterol was determined spectrophotometrically by using p-anisidine as a test reagent of the enzymatic reaction of cholesterol through a bienzymic reactor in which cholesterol oxidase and horseradish peroxidase were noncovalently immobilized in controlled pore,glass beads. 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Abstract:
An alternative method for the hydrolysis of cholesterol esters in animal grease samples has been developed. The method consists of the microwave-assisted treatment of 4 g of animal fat or oil with 40 mL of an ethanolic KOH solution inside a 115 mL closed reactor in which samples were irradiated for 2.5 min at 50% power level of an exit power of 700 W. After extraction with petroleum ether and dissolution of the unsaponifiables in toluene, total cholesterol was determined spectrophotometrically by using p-anisidine as a test reagent of the enzymatic reaction of cholesterol through a bienzymic reactor in which cholesterol oxidase and horseradish peroxidase were noncovalently immobilized in controlled pore,glass beads. The method provided a quantitative recovery of spiked free cholesterol (100% recovery for an added concentration level of 36 mg g-1) and cholesteryl palmitate (98.7% recovery for an added concentration of 37 mg g-1) and results comparable to those obtained after saponification with ethanolic KOH at 90°C under reflux conditions for 1 h, saving a considerable time with a comparable figures of merit which involve a limit of detection of 1 x 10^-6 M total cholesterol an average interday relative standard deviation of 3.5% for three independent analysis of a series of different samples.
Cholesterol
Fat
Immobilized enzyme
Controlled pore glass
Method comparison
"Flow Injection Determination Of Free And Total Cholesterol In Animal Greases Using Enzymes In Non-aqueous Media"
Analyst
1998 Volume 123, Issue 5 Pages 999-1003
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The bienzymic reactor exhibits a good stability in the water-restricted environment, being possible to perform more than 180 analyzes during a period of 10 d with 1 mg of HRP, and 1 mg of COD, equivalent to 220 purpurogallin units and 23 U, respectively.', 'language' => 'English', 'updated' => '2020-12-28 11:25:15', 'sjccheck' => 'Yes', 'sjccheckdate' => '0000-00-00 00:00:00', 'hits' => '11', 'urlcheck' => '2014-10-12 09:52:06', 'urlcheckcode' => 'HTTP/1.1 302 Found', 'pauthor_id' => '00110', 'pauthor' => '!De La Guardia, M.', 'address' => 'pau', 'email' => 'pau', 'notes' => null, 'url' => '10.1039/a800622i', 'urltype' => 'doi', 'gotpdf' => 'yes', 'partial' => 'no', 'notanalyte' => '', 'citation' => ''Flow injection determination of free and total cholesterol in animal greases using enzymes in non-aqueous media', Analyst, 1998 123(5) 999-1003', 'firstchar' => 'F', 'twochars' => 'Fl', 'CitationsTechnique' => array( [maximum depth reached] ), 'Analyte' => array( [maximum depth reached] ), 'Matrix' => array( [maximum depth reached] ), 'Keyword' => array( [maximum depth reached] ) ) ) ) $c = array( 'id' => '007973', 'authors' => 'Pineiro Avila, G.', 'authorsweb' => 'Gerardo Piñeiro-Avila, Amparo Salvador and Miguel de la Guardia', 'title' => 'Flow injection determination of free and total cholesterol in animal greases using enzymes in non-aqueous media', 'journal' => 'Analyst', 'journal_id' => '0864', 'fadid' => 'ANAL1998V0123P00999', 'year' => '1998', 'volume' => '123', 'issue' => '5', 'startpage' => '999', 'endpage' => '1003', 'type' => 'Journal Article', 'analytes' => ';0629;0631;', 'matrices' => ';0716;0718;0722;0226;', 'techniques' => ';0493;0422;', 'keywords' => ';0305;', 'abstract' => 'A non-covalently co-immobilized bienzymic reactor of horseradish peroxidase (HRP) and cholesterol oxidase (COD), operating in a continuous organic flowing stream of 1 x 10^-3 M p-anisidine in buffer-saturated (pH 7.0) toluene, has been employed for cholesterol determination in animal greases, such as pig, beef, and chicken fat, and codfish liver oil. 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Abstract:
A non-covalently co-immobilized bienzymic reactor of horseradish peroxidase (HRP) and cholesterol oxidase (COD), operating in a continuous organic flowing stream of 1 x 10^-3 M p-anisidine in buffer-saturated (pH 7.0) toluene, has been employed for cholesterol determination in animal greases, such as pig, beef, and chicken fat, and codfish liver oil. The method provides a good linear relationship up to 1.8 x 10^-3 M cholesterol and average recoveries of 99.5%, a high sensitivity, with a detection limit of 1 x 10^-6 M of cholesterol and a good precision (an interday RSD of 1.8% for the determination of total cholesterol in a codfish oil sample). The method permits the direct spectrophotometric determination of free cholesterol present in animal grease samples without any pre-treatment, and the total cholesterol determination after a microwave-assisted sapon. The bienzymic reactor exhibits a good stability in the water-restricted environment, being possible to perform more than 180 analyzes during a period of 10 d with 1 mg of HRP, and 1 mg of COD, equivalent to 220 purpurogallin units and 23 U, respectively.
Cholesterol, free
Cholesterol, total
Fat
Fat
Fat
Liver
Organic solvent