Determination of cortisol in human plasma by stable isotope dilution mass spectrometry.
Cortisol selectively labelled with 2H at the 19-methyl and the C-1 position (cortisol-d5) was synthesized and used as an internal standard in stable isotope dilution mass spectrometry in order to determine cortisol in human plasma. A capillary gas chromatographic/mass spectrometric method provided a sensitive and reliable technique with good accuracy, precision and reproducibility without complex corrections for contributions by using cortisol-d5 as an internal standard. For calculation of plasma cortisol, peak areas were measured by selected ion monitoring on the characteristic fragment ions of the dimethoxime tri(trimethylsilyl) derivatives of cortisol and cortisol-d5 (m/z 605 and 610, respectively). The sensitivity of the gas chromatographic/mass spectrometric assay was 1.02 ng per injection, with a signal-to-noise ratio of about 6. The inter- and intra-assay coefficients of variation for plasma sample were 3.07% and 1.77%, respectively.
Kasuya
Y
Y
Tokyo College of Pharmacy, Japan.
Furuta
T
T
Hirota
N
N
D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007553:Isotope Labeling; D013058:Mass Spectrometry
D003903:Deuterium; D006854:Hydrocortisone