Last data update: May 06, 2024. (Total: 46732 publications since 2009)
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Query Trace: Encisco SE[original query] |
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Isotope dilution ultra performance liquid chromatography-tandem mass spectrometry method for simultaneous measurement of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3 and 3-epi-25-hydroxyvitamin D3 in human serum
Schleicher RL , Encisco SE , Chaudhary-Webb M , Paliakov E , Pfeiffer CM . Clin Chim Acta 2011 412 1594-9 BACKGROUND: An ultra performance liquid chromatography-tandem mass spectrometry method with calibration traceable to NIST SRM was developed and validated to measure concentrations of 25-hydroxyvitamin D(2) (25OHD(2)), 25-hydroxyvitamin D(3) (25OHD(3)) and the C-3 epimer of 25OHD(3) (epi-25OHD(3)) in human serum. METHODS: Tri- and hexa-deuterated internal standards were added to serum (100mul) to monitor recovery. Liquid-liquid extraction was used to extract the hexane-soluble materials. Calibration solutions [8-100nmol/L 25OHD(2,) 12-150nmol/L 25OHD(3), and 4-50nmol/L epi-25OHD(3)] prepared in phosphate-buffered saline containing 4% albumin were similarly processed. Using a pentafluorophenyl column (2.1x100mm) and isocratic methanol/water (72/28, v/v) flowing at 0.4ml/min, run time was 14min per sample; 25OHD(3) and epi-25OHD(3) were baseline separated. Atmospheric pressure chemical ionization in the positive ion mode with selected reaction monitoring captured the following transitions: 25OHD(2), m/z 395.3>377.3 (209.1 qualifier); (epi-)25OHD(3), m/z 383.3>365.3 (105.1 qualifier); d(3)-25OHD(2)m/z 398.3>380.3; and d(6)-25OHD(3), m/z 389.3>371.3. RESULTS: Recovery averaged ≥98%. Total imprecision was ≤10% when concentrations were ≥20nmol/l. Bias averaged <5%. Detection limits were <5nmol/l. Median (nmol/l) 25OHD(2), 25OHD(3) and epi-25OHD(3) were quantitated in 98 blood donors (<LOD, 56.0, <LOD) and 35 pregnant women (<LOD, 87.6, 3.70). CONCLUSIONS: This method is highly accurate, precise and specific. |
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