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Yu S.,Peking Union Medical College | Yu S.,Beijing Hospital Institute of Geriatrics | Dong J.,Beijing Hospital Institute of Geriatrics | Zhou W.,Beijing Hospital National Center for Clinical Laboratories | And 9 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2014

We described a rapid and precise method for simultaneous quantification of eleven fatty acids in human serum cholesteryl esters (CEFAs) by liquid chromatography and tandem mass spectrometry (LC-MS/MS). After extraction of serum lipids with isopropanol, CEFAs were separated on reversed phase liquid chromatography and detected by mass spectrometry in positive ion mode with multiple reaction monitor. Individual CEFA was quantified by peak area normalization method and expressed as molar percent of total CEFAs. The run time was less than 5min and detection limits were from 0.31 to 14.50×10-5mmol/L. Recoveries of the CEFAs ranged from 91.85% to 104.83% with a mean of 99.12%. The intra and total CVs for the measurement of CEFAs were 0.87-7.70% and 1.02-7.65%, respectively. This LC-MS/MS method required no internal standards, eliminated natural isotope interferences, and provided reproducible and reliable results for 11 major CEFAs in human serum. This method can be used in monitoring and evaluating dietary fatty acid intake. Additional studies are needed to evaluate the associations between serum CEFAs and cardiovascular disease risk factors. © 2014 Elsevier B.V.

Zhou W.,Peking Union Medical College | Zhou W.,Beijing Hospital Institute of Geriatrics | Li H.,Beijing Hospital Institute of Geriatrics | Dong J.,Beijing Hospital Institute of Geriatrics | And 5 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2011

Background: Accurate cholesterol measurements are essential for the prevention and management of cardiovascular diseases. Quality assurance of cholesterol measurements requires reference methods. Methods: An isotope dilution liquid chromatography mass spectrometric (ID/LC/MS) method was developed. Serum samples were sampled volumetrically using automated dilutors, treated with potassium hydroxide and equilibrated with 3,4-13C 2 cholesterol. The natural cholesterol and the internal standard were extracted with hexane and oxidized to cholest-4-en-3,6-diones with chromic acid. The oxidation products were separated on reversed phase LC and detected by tandem MS. The method was calibrated using aqueous cholesterol calibrators and the calibration function was established with a polynomial regression. Results: The correlation coefficients of the calibration curves were always >0.9999. The coefficients of variation (CV) of the volumetric sampling and the LC/MS analysis averaged 0.22% and 0.50%, respectively, and the total measurement CV was 0.60%. Other sources of measurement uncertainty were minor. Results on certified reference materials agreed within 1% of the certified values. Conclusions: An ID/LC/MS method for serum cholesterol has been developed. The method is simple and accurate and may be used as a candidate reference method. © 2011 by Walter de Gruyter Berlin New York.

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