Analyses for progesterone in serum by gas chromatography/mass spectrometry: target data for external quality assessment of routine assays.

1984 ◽  
Vol 30 (10) ◽  
pp. 1696-1700 ◽  
Author(s):  
S J Gaskell ◽  
B G Brownsey ◽  
G V Groom
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Accurate Determination ◽  
Gas Chromatography Mass Spectrometry ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Chromatography Mass Spectrometry ◽  
Target Data

Abstract We describe a procedure for measuring progesterone in plasma and serum by isotope dilution and mass spectrometry. Extraction with use of a microcellulose-coupled antiserum is followed by conversion to the 3-enol heptafluorobutyrate and analysis by gas chromatography/mass spectrometry (GC/MS) with selected ion monitoring, at a resolution of 5000. Interassay CVs were 1.5 to 5.4% for the concentration range 13 to 43 nmol/L. Analyses of various serum volumes showed excellent linearity. Accurate determination of progesterone added to serum was demonstrated. Plasma and serum pools were analyzed to provide target data for use in the U.K. national external quality-assessment scheme for progesterone assays. Direct, non-extraction radioimmunoassays and those incorporating solvent extraction both showed a positive bias with respect to data obtained by the present procedure, but the bias was more marked with the direct assays.

External quality assessment of assays for cortisol in plasma: use of target data obtained by gas chromatography/mass spectrometry.

1983 ◽  
Vol 29 (5) ◽  
pp. 862-867 ◽  
Author(s):  
S J Gaskell ◽  
C J Collins ◽  
G C Thorne ◽  
G V Groom
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Solvent Extraction ◽  
Quality Assessment ◽  
High Resolution Mass Spectrometry ◽  
External Quality Assessment ◽  
Gas Chromatography Mass Spectrometry ◽  
Good Precision ◽  
External Quality ◽  
Target Data

Abstract We describe procedures for measuring cortisol in plasma and serum by isotope dilution and mass spectrometry. A method that incorporated solvent extraction, derivatization, and gas chromatography/high-resolution mass spectrometry provided data of good precision; interassay CVs were generally 3 to 4% for the concentration range of 100-650 nmol/L. Replacing solvent extraction with extraction on a column of Lipidex 1000 or extraction by immunoadsorption yielded data in excellent agreement with the first method. Plasma and serum pools were analyzed to provide target data for use in the U.K. National External Quality Assessment Scheme for cortisol assays. Routine laboratory assays, as judged by comparison with mass-spectrometric data, were generally positively biased except for analysis of a charcoal-stripped plasma supplemented with cortisol. The results emphasize the importance of using unadulterated plasma or serum pools in assessments of steroid assay procedures.

scholarly journals Measurement of Urea in Human Serum by Isotope Dilution Mass Spectrometry: A Reference Procedure

1999 ◽  
Vol 45 (9) ◽  
pp. 1523-1529 ◽  
Author(s):  
Anja Kessler ◽  
Lothar Siekmann
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Human Serum ◽  
Isotope Dilution ◽  
Accurate Determination ◽  
Measurement Procedure ◽  
Gas Chromatography Mass Spectrometry ◽  
Reference Measurement ◽  
Chromatography Mass Spectrometry ◽  
Reference Measurement Procedure

Abstract Background: A reference measurement procedure is needed to demonstrate the traceability of results of urea measurements in human serum. We developed a measurement procedure using the principle of isotope dilution gas chromatography/mass spectrometry. Methods: [13C,15N2]Urea as internal standard was added to a serum sample and equilibrated with endogenous nonlabeled urea. For the preparation of calibrators, the same amount of labeled urea was mixed with known amounts of nonlabeled urea. The serum samples were treated with ethanol to remove proteins by precipitation. The labeled and nonlabeled urea of the samples was converted into a trimethylsilyl derivative of 2-hydroxypyrimidine. The gas chromatography/mass spectrometry system was adjusted to monitor m/z 153 and 168 for the nonlabeled urea derivative and m/z 156 and 171 for the isotopically labeled analogs. The results of the determination were calculated from peak ratios by a hyperbolic calculation function based on the theory of isotope dilution analysis. Results: The procedure was applied to control samples and patient samples and evaluated with respect to its trueness and precision. The standard uncertainty of the results was 0.47–1.72%. Conclusions:This reference measurement procedure allows values to be assigned to controls and calibrators that are traceable to the primary urea reference material of NIST and, therefore, to the Système International unit “mole” with a low degree of uncertainty. This procedure provides a tool for the highly accurate determination of urea in control materials as well as in patient sera.

Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring.

1981 ◽  
Vol 27 (7) ◽  
pp. 1165-1170 ◽  
Author(s):  
E M Finlay ◽  
S J Gaskell
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
High Resolution ◽  
External Quality Assessment ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Internal Standards ◽  
Metastable Peak ◽  
Chromatography Mass Spectrometry

Abstract Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. [2H3]Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r = 0.997; y = 1.008x + 0.564 nmol/L).

scholarly journals Discrimination of Malus Taxa with Different Scent Intensities Using Electronic Nose and Gas Chromatography–Mass Spectrometry

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3429 ◽  
Author(s):  
Junjun Fan ◽  
Wangxiang Zhang ◽  
Ting Zhou ◽  
Dandan Zhang ◽  
Donglin Zhang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Electronic Nose ◽  
Floral Scent ◽  
Accurate Determination ◽  
Principal Component ◽  
Gas Chromatography Mass Spectrometry ◽  
Least Squares Regression ◽  
Chromatography Mass Spectrometry ◽  
Nitrogen Containing Compounds

Floral scent is important in plant reproduction and also has aesthetic implications. However, the accurate determination of aroma is presently limited by the available collection and analysis tools. In this study, the floral scents of four crabapple taxa exhibiting faint, weak, clear, and strong scent intensities were comparatively analyzed by electronic nose (E-nose) and gas chromatography–mass spectrometry (GC–MS). The E-nose was able to effectively group the different taxa in the principal component analysis in correspondence with scent intensity. GC–MS analysis identified a total of 60 volatile compounds. The content of nitrogen-containing compounds and aliphatics and the number of unique components of the more aromatic taxa was significantly higher than the less aromatic taxa. α-Cedrene, β-cedrene, 5-methyl-1,3-dihydro-2H-benzimidazol-2-one, benzyl alcohol, linalool, and 4-pyrrolidinopyridine contributed significantly to taxon separation. The pattern recognition results confirmed that the E-nose results corroborated the GC–MS results. Furthermore, partial least squares regression analysis between the aromatic constituents and sensors indicated that particular sensors were highly sensitive to N-containing compounds, aliphatics, and terpenes. In conclusion, the E-nose is capable of discriminating crabapple taxa of different scent intensities in both a qualitative and quantitative respect, presenting a rapid and accurate reference approach for future applications.

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