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Yu S.,Peking Union Medical College | Zhou W.,Beijing Hospital National Center for Clinical Laboratories | Cheng X.,Peking Union Medical College | Fang H.,Peking Union Medical College | And 4 more authors.
Clinical Biochemistry | Year: 2016

Objectives: To develop a rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method with ability to separate 3-epi 25OHD3 (EPI-LC-MS/MS) from 25OHD3, and evaluate the effects of 3-epi 25OHD3 on routine LC-MS/MS that cannot separate 3-epi 25OHD3 (NEPI-LC-MS/MS). Design and methods: Performance of the newly built EPI-LC-MS/MS was validated, and 982 samples were analyzed and compared by the two methods. Results: Both methods showed a linearity coefficient correlation exceeding 0.999 in the 6.25-500nmol/L range for 25OHD2 and 25OHD3. Moreover, they showed a between run coefficient variation (CV) and total CV of < 5% for 25OHD2 and 25OHD3. The results of the accuracy test showed that the bias was below 6.19% in the absence of 3-epi 25OHD3. Comparison of the 25OHD results obtained by the two methods for 982 patients (age 1-100years) revealed excellent clinical agreement (Cohen's kappa=0.875) and correlation (R2=0.973). Among the 982patients, only 73patients had 3-epi 25OHD3 (>6.25nmol/L); out of these 73patients, the 3-epi 25OHD3 level in 58patients was between 6.25 and 12.5nmol/L. In patients with <375nmol/L 25OHD (25OHD2+25OHD3), only 8 had 3-epi 25OHD3 levels exceeding 12.5nmol/L (range: 13.3 - 27.5nmol/L). Among samples containing 3-epi 25OHD3, only three were separated into different 25OHD-deficiency groups using the above methods. Conclusion: A rapid and precise EPI-LC-MS/MS method for measuring 25OHD with efficient separation of 3-epi 25OHD3 was developed. Our results showed that 3-epi 25OHD3 had little effect on the routinely used NEPI-LC-MS/MS. © 2016 The Canadian Society of Clinical Chemists. Source

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. Source

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