scholarly journals An isotope dilution mass spectrometric measurement procedure has the potential of being a very good reference measurement procedure, but is not a “definitive” one

2010 ◽  
Vol 15 (6) ◽  
pp. 321-322 ◽  
Author(s):  
Paul De Bièvre
Keyword(s):  
Isotope Dilution ◽  
Measurement Procedure ◽  
Mass Spectrometric ◽  
Mass Spectrometric Measurement ◽  
Reference Measurement ◽  
Spectrometric Measurement ◽  
Reference Measurement Procedure

scholarly journals Proposed Serum Cholesterol Reference Measurement Procedure by Gas Chromatography–Isotope Dilution Mass Spectrometry

2011 ◽  
Vol 57 (4) ◽  
pp. 614-622 ◽  
Author(s):  
Selvin H Edwards ◽  
Mary M Kimberly ◽  
Susan D Pyatt ◽  
Shelton L Stribling ◽  
Kara D Dobbin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Serum Cholesterol ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
Measurement Procedure ◽  
Standard Reference Materials ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
The Mean

BACKGROUND Our purpose was to establish a mass spectrometry reference measurement procedure (RMP) for cholesterol to use in the CDC's standardization programs. We explored a gas chromatography–isotope dilution mass spectrometry (GC-IDMS) procedure using a multilevel standard calibration curve to quantify samples with varying cholesterol concentrations. METHODS We calibrated the mass spectrometry instrument by isotope dilution with a pure primary standard reference material and an isotopically enriched cholesterol analog as the internal standard (IS). We diluted the serum samples with Tris-HCl buffer (pH 7.4, 0.05 mol/L, 0.25% Triton X-100) before analysis. We used 17 serum pools, 10 native samples, and 2 standard reference materials (SRMs). We compared the GC-IDMS measurements with the CDC's modified Abell–Levy–Brodie–Kendall (AK) RMP measurements and assessed method accuracy by analyzing 2 SRMs. We evaluated the procedure for lack of interference by analyzing serum spiked with a mixture of 7 sterols. RESULTS The mean percent bias between the AK and the GC-IDMS RMP was 1.6% for all samples examined. The mean percent bias from NIST's RMP was 0.5% for the SRMs. The total %CVs for SRM 1951b levels I and II were 0.61 and 0.73%, respectively. We found that none of the sterols investigated interfered with the cholesterol measurement. CONCLUSIONS The low imprecision, linear response, lack of interferences, and acceptable bias vs the NIST primary RMP qualifies this procedure as an RMP for determining serum cholesterol. The CDC will adopt and implement this GC-IDMS procedure for cholesterol standardization.

scholarly journals Feasibility of Standardization of Serum C-Peptide Immunoassays with Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry

2006 ◽  
Vol 52 (6) ◽  
pp. 1193-1196 ◽  
Author(s):  
Diego Rodríguez Cabaleiro ◽  
Dietmar Stöckl ◽  
Jean M Kaufman ◽  
Tom Fiers ◽  
Linda M Thienpont
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Isotope Dilution ◽  
Method Comparison ◽  
Measurement Procedure ◽  
Tandem Ms ◽  
C Peptide ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
Lc Tandem Ms

Abstract Background: Serum C-peptide concentrations reflect pancreatic function in different clinical and diagnostic settings; however, the utility of C-peptide testing is limited by the lack of standardized commercial immunoassays. Standardization can best be done by split-sample comparison with a hierarchically higher reference measurement procedure with a set of native sera. For serum peptides, isotope-dilution liquid chromatography–mass spectrometry (ID-LC/MS) is recommended as a reference measurement procedure. Methods: We evaluated the analytical performance characteristics of an ID-LC/tandem MS procedure for measurement of serum C-peptide after a 2-step solid-phase extraction. To investigate the feasibility of this procedure for use in standardization, we also performed a method comparison with 3 representative commercial assays. Results: The ID-LC/tandem MS procedure showed maximum within-run, between-run, and total CVs on dedicated sera (C-peptide concentrations, 1.6 and 4.0 μg/L) of 2.1%, 2.5%, and 2.9%, respectively; an accuracy of 94.6%–104.1%; a minimum trueness of 98.1% (95% confidence interval, 96.2%–100.0%), and limits of quantification and detection of 0.15 and 0.03 μg/L, respectively. Deming linear regression analysis of the method-comparison data showed that the immunoassays correlated well with ID-MS and were specific, but lacked intercomparability and trueness. We propose that the deficiencies can be resolved by recalibration on the basis of the method comparison. Conclusions: The ID-LC/tandem MS procedure is suitable for specific and accurate measurement of basal and stimulated serum concentrations of proinsulin C-peptide fragment 33–63 and is suitable for use in standardization of C-peptide immunoassays.

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.

Plutonium-239 half life determined by isotope dilution mass spectrometric measurement of grown-in uranium-235

1978 ◽  
Vol 29 (8) ◽  
pp. 509-515 ◽  
Author(s):  
S.Fredric Marsh ◽  
Robert M. Abernathey ◽  
Richard J. Beckman ◽  
R.Keith Zeigler ◽  
James E. Rein
Keyword(s):  
Isotope Dilution ◽  
Half Life ◽  
Mass Spectrometric ◽  
Mass Spectrometric Measurement ◽  
Spectrometric Measurement
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