scholarly journals Standardization of C-Peptide Measurements in Urine by Method Comparison with Isotope-Dilution Mass Spectrometry

2003 ◽  
Vol 49 (6) ◽  
pp. 992-994 ◽  
Author(s):  
Colette Fierens ◽  
Dietmar Stöckl ◽  
Dimitri Baetens ◽  
André P De Leenheer ◽  
Linda M Thienpont
Keyword(s):  
Mass Spectrometry ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
Method Comparison ◽  
C Peptide

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 Use of Frozen Sera for FT4 Standardization: Investigation by Equilibrium Dialysis Combined with Isotope Dilution-Mass Spectrometry and Immunoassay

2006 ◽  
Vol 52 (9) ◽  
pp. 1817-1821 ◽  
Author(s):  
Katleen Van Uytfanghe ◽  
Dietmar Stöckl ◽  
H Alec Ross ◽  
Linda M Thienpont
Keyword(s):  
Mass Spectrometry ◽  
Isotope Dilution ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Isotope Dilution Mass Spectrometry ◽  
Method Comparison ◽  
Tandem Ms ◽  
Limit Of Quantification ◽  
Lc Tandem Ms

Abstract Background: Serum-free thyroxine (FT4) testing is recommended for diagnosis or monitoring of thyroid dysfunction, particularly in cases of hormone binding abnormalities. However, the poor intermethod agreement among commercial FT4 assays suggests a need for standardization with a hierarchically higher measurement procedure. To that purpose, we applied equilibrium dialysis (ED) in combination with isotope dilution-liquid chromatography/tandem mass spectrometry (ID-LC-tandem MS). Methods: After ED, we collected dialysate into tubes containing [13C6]-T4 for ID and [13C9]-T4 as carrier, purified the samples by solid-phase extraction, and analyzed them with LC/tandem MS. We evaluated the procedure’s analytical performance and tested its suitability for measurement of hypo-, eu-, and hyperthyroid serum FT4 concentrations. We conducted a pilot method comparison study with 3 commercial assays to investigate whether frozen sera could be used for the purpose of FT4 standardization. Results: The within-run, between-run, and total CVs (inclusive ED) were 3.7%, 4.2%, and 5.6%, respectively (17.7 pmol/L; n = 20). The mean accuracy, estimated from recovery experiments with dialysate and dialysis buffer supplemented at 8.7, 18.7, and 33.5 pmol/L, and from analysis of certified sera gravimetrically diluted to 9.8, 19.2, and 34.8 pmol/L, was 98.0% to 102.8%. The procedure’s limit of detection and limit of quantification were 0.5 and 1.3 pmol/L, respectively. The method comparison demonstrated the suitability of the selected sera for standardization of FT4 assays and confirmed the lack of assay comparability. Conclusions: We demonstrated that the described ED-ID-LC/tandem MS procedure and the selected type of sera qualify for standardization of FT4 measurements.

Development of a primary reference material of natural C-reactive protein: verification of its natural pentameric structure and certification by two isotope dilution mass spectrometry

2021 ◽  
Vol 13 (5) ◽  
pp. 626-635
Author(s):  
Jianyi Liu ◽  
Wen Zhu ◽  
Haofeng Sun ◽  
Dewei Song ◽  
Peng Xiao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Reference Material ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Primary Reference

Development of a primary reference material of natural C-reactive protein: verification of its natural pentameric structure and certification by two isotope dilution mass spectrometry.

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