scholarly journals Quantitative Insulin Analysis Using Liquid Chromatography–Tandem Mass Spectrometry in a High-Throughput Clinical Laboratory

2013 ◽  
Vol 59 (9) ◽  
pp. 1349-1356 ◽  
Author(s):  
Zhaohui Chen ◽  
Michael P Caulfield ◽  
Michael J McPhaul ◽  
Richard E Reitz ◽  
Steven W Taylor ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Human Insulin ◽  
High Throughput ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Deming Regression ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass

BACKGROUND Circulating insulin concentrations reflect the amount of endogenous insulin produced by the pancreas and can be monitored to check for insulin resistance. Insulin is commonly measured using immunochemiluminometric assays (ICMA). Unfortunately, differing crossreactivities of the various ICMA antibodies have led to variability in assay results. In contrast, liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based approaches can provide a highly specific alternative to immunoassays. METHODS Insulin was extracted from patient serum and reduced to liberate the insulin B chain. Subsequent resolution of the peptide was achieved by LC coupled to triple-quadrupole MS. Selected-reaction monitoring of B-chain transitions was used for quantification. Recombinant human insulin was used as a calibrator and was compared against the National Institute for Biological Standards and Control (NIBSC) reference standard. Bovine insulin and a stable isotopic-labeled (13C/15N) human insulin B chain were used and compared as internal standards. RESULTS The LC-MS/MS assay described herein has been validated according to CLIA guidelines with a limit of detection of 1.8 μIU/mL (10.8 pmol/L) and a limit of quantitation of 3 μIU/mL (18.0 pmol/L). A correlation between the LC-MS/MS assay and a US Food and Drug Administration-approved ICMA was completed for patient samples and the resulting Deming regression revealed good agreement. A reference interval for the assay was established. CONCLUSIONS A simple, high-throughput, quantitative LC-MS/MS insulin assay traceable to the NIBSC standard has been successfully developed and validated.

scholarly journals State-of-the-Art of Serum Testosterone Measurement by Isotope Dilution–Liquid Chromatography– Tandem Mass Spectrometry

2008 ◽  
Vol 54 (8) ◽  
pp. 1290-1297 ◽  
Author(s):  
Linda M Thienpont ◽  
Katleen Van Uytfanghe ◽  
Stuart Blincko ◽  
Carol S Ramsay ◽  
Hui Xie ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Isotope Dilution ◽  
Total Error ◽  
Serum Testosterone ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Deming Regression ◽  
Liquid Chromatography Tandem Mass

Abstract Background: The recent interest of clinical laboratories in developing serum testosterone assays based on isotope dilution–liquid chromatography–tandem mass spectrometry (ID-LC-MS/MS) stems from the lack of accuracy of direct immunoassays. In this study, we assessed the accuracy and state of standardization (traceability) of 4 published ID-LC-MS/MS procedures in a method comparison with an ID–gas chromatography (GC)–MS reference measurement procedure listed in the database of the Joint Committee for Traceability in Laboratory Medicine. Methods: The study used 58 specimens from different patient categories. Each specimen was measured in triplicate (ID-LC-MS/MS) and quadruplicate (ID-GC-MS) in independent runs. Results: The testosterone concentrations by ID-GC-MS were 0.2–4.4 nmol/L (women), 0.2–2.0 nmol/L (hypogonadal man), and 10.1–31.3 nmol/L (normogonadal men). For ID-GC-MS, the CV was nearly constant, with a median of 1.0%; for ID-LC-MS/MS, it was concentration-dependent, with a median of up to 8%. Weighted Deming regression gave mean slopes, intercepts, and correlation coefficients of 0.90–1.11, −0.055–0.013 nmol/L, and 0.993–0.997, respectively. The % difference plot showed between 7% and 26% of the results outside a total error limit of 14%, with median deviations from ID-GC-MS between −9.6 and 0.4%. Conclusions: This study demonstrated fairly good accuracy and standardization of the tested ID-LC-MS/MS procedures. Performance differences between procedures were evident in some instances, due to improper calibration and between-run calibration control. This emphasizes the need for thorough validation, including traceability, of new ID-LC-MS/MS procedures.

scholarly journals Development of a method for the measurement of dehydroepiandrosterone sulphate by liquid chromatography-tandem mass spectrometry

2005 ◽  
Vol 42 (6) ◽  
pp. 468-474 ◽  
Author(s):  
C A Chadwick ◽  
L J Owen ◽  
B G Keevil
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Lower Limit ◽  
Internal Standard ◽  
Tandem Mass ◽  
Dehydroepiandrosterone Sulphate ◽  
Chromatography Tandem Mass Spectrometry ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass

Background: Dehydroepiandrosterone sulphate (DHEAS) is a steroid that is increasingly being recognized as a potential drug of abuse in many countries. This is due to its reputation as a hormone that may be able to retard the ageing process. The measurement of DHEAS is useful in the diagnosis of medical conditions such as congenital adrenal hyperplasia and polycystic ovary syndrome. Thus, a liquid chromatography-tandem mass spectrometry method has been developed to determine DHEAS concentrations in human serum. Method: The chromatography was performed using a WatersTM 2795 Alliance HT LC system coupled to a Mercury Fusion-RP column fitted with a SecurityGuardTM column. Results: DHEAS and the internal standard, deuterated DHEAS, both had a retention time of 1.5 min. The transition determined by the Micromass QuattroTM tandem mass spectrometer for DHEAS was m/z 367.3>96.7 and for the internal standard m/z 369.3>96.6. The method was linear up to 20 µmol/L; the lower limit of detection and the lower limit of quantitation were both 1 µmol/L. The intra- and interassay imprecision were <11% over a concentration range of 1-18 µmol/L for the in-house quality control and <12% for the intra- and interassay imprecision for the Bio-Rad Lyphocheck QC. Conclusion: The measurement of DHEAS by liquid chromatography-tandem mass spectrometry is robust and has a simple sample preparation procedure with a rapid cycle time of only 4 min.

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