title: Electron-capture gas chromatography as a sensitive method for measuring subnanogram amounts of cholesterol in saliva and urine.
abstract: This is a sensitive method, suitable for measuring subanogram amounts of cholesterol. Cholesterol and the internal standard, epicoprostanol (5-beta-cholestan-3-alpha-ol), are derivatized with pentafluorobenzoyl chloride and detected by electron-capture gas chromatography. The pentafluorobenzoyl esters of cholesterol and the internal standard are easily formed and possess excellent chromatographic and electron-capturing properties. The lower limit of detection of the method, approximately 100 pg injected, is about 500-fold as sensitive as chromatographic methods involving flame-ionization detection. Within-day and between-day coefficients of variation were 4.2% and 8.2%, respectively, for determinations of a urinary cholesterol concentration of 570 micrograms/L (1.47 mumol/L). Such sensitivity permits analysis for cholesterol in (e.g.) physiological fluids, tissue samples, and cell cultures that contain very low concentrations of cholesterol.
authors.affiliation: Internal Medicine Branch, USAF School of Aerospace Medicine, Brooks Air Force Base, TX 78235-5301.
authors.forename: H A
authors.initials: HA
authors.lastname: Schwertner
authors.forename: E R
authors.initials: ER
authors.lastname: Johnson
authors.forename: T E
authors.initials: TE
authors.lastname: Lane
mesh_terms: D001565:Benzoates; D002784:Cholesterol / Q000032:analysis* / Q000097:blood; D002849:Chromatography, Gas / Q000706:statistics & numerical data; D006801:Humans; D008832:Microchemistry; D011786:Quality Control; D012016:Reference Values; D012463:Saliva / Q000032:analysis*; D005464:Fluorobenzenes; D005466:Fluorocarbons
chemical_list: D001565:Benzoates; D002784:Cholesterol; C014737:pentafluorobenzoyl chloride; D005464:Fluorobenzenes; D005466:Fluorocarbons