Determination of cortisol production rates with contemporary liquid chromatography-mass spectrometry to measure cortisol-d3 dilution after infusion of deuterated tracer

Bethany Klopfenstein, Jonathan Purnell, David D. Brandon, Lorne M. Isabelle, Andrea De Barber

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Objectives: Measurement of 24-h cortisol production rate (CPR) using steady-state infusion of deuterated cortisol and analysis of stable-isotope dilution by MS is a valuable tool to examine hypothalamic-pituitary-adrenal axis activity in humans. We have developed and validated an improved method for measuring cortisol dilution with contemporary LC-MS technology. Design and methods: Plasma samples and calibrators were extracted with ethylacetate. LC-MS was performed with a Surveyor HPLC and TSQ Quantum triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) source. Results: Selectivity was improved over previous methods via elimination of an interferent identified as 20β-dihydrocortisol. The LLOQ for cortisol-d3 was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d3, with correlation coefficients >0.995. Conclusions: This APCI LC-MS method offers simplified sample work-up and analysis and enables selective detection of the low concentration of cortisol-d3 infused for determination of 24-h CPR.

Original languageEnglish (US)
Pages (from-to)430-434
Number of pages5
JournalClinical Biochemistry
Volume44
Issue number5-6
DOIs
StatePublished - Apr 2011

Fingerprint

Liquid chromatography
Liquid Chromatography
Dilution
Mass spectrometry
Hydrocortisone
Mass Spectrometry
Atmospheric Pressure
Atmospheric pressure
Plasmas
Mass spectrometers
Ion sources
Human Activities
Isotopes
Ionization
High Pressure Liquid Chromatography
Technology

Keywords

  • 20β-Dihydrocortisol
  • Atmospheric pressure chemical ionization
  • Cortisol production rate
  • Liquid chromatography-mass spectrometry
  • Plasma

ASJC Scopus subject areas

  • Clinical Biochemistry

Cite this

Determination of cortisol production rates with contemporary liquid chromatography-mass spectrometry to measure cortisol-d3 dilution after infusion of deuterated tracer. / Klopfenstein, Bethany; Purnell, Jonathan; Brandon, David D.; Isabelle, Lorne M.; De Barber, Andrea.

In: Clinical Biochemistry, Vol. 44, No. 5-6, 04.2011, p. 430-434.

Research output: Contribution to journalArticle

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N2 - Objectives: Measurement of 24-h cortisol production rate (CPR) using steady-state infusion of deuterated cortisol and analysis of stable-isotope dilution by MS is a valuable tool to examine hypothalamic-pituitary-adrenal axis activity in humans. We have developed and validated an improved method for measuring cortisol dilution with contemporary LC-MS technology. Design and methods: Plasma samples and calibrators were extracted with ethylacetate. LC-MS was performed with a Surveyor HPLC and TSQ Quantum triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) source. Results: Selectivity was improved over previous methods via elimination of an interferent identified as 20β-dihydrocortisol. The LLOQ for cortisol-d3 was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d3, with correlation coefficients >0.995. Conclusions: This APCI LC-MS method offers simplified sample work-up and analysis and enables selective detection of the low concentration of cortisol-d3 infused for determination of 24-h CPR.

AB - Objectives: Measurement of 24-h cortisol production rate (CPR) using steady-state infusion of deuterated cortisol and analysis of stable-isotope dilution by MS is a valuable tool to examine hypothalamic-pituitary-adrenal axis activity in humans. We have developed and validated an improved method for measuring cortisol dilution with contemporary LC-MS technology. Design and methods: Plasma samples and calibrators were extracted with ethylacetate. LC-MS was performed with a Surveyor HPLC and TSQ Quantum triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) source. Results: Selectivity was improved over previous methods via elimination of an interferent identified as 20β-dihydrocortisol. The LLOQ for cortisol-d3 was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d3, with correlation coefficients >0.995. Conclusions: This APCI LC-MS method offers simplified sample work-up and analysis and enables selective detection of the low concentration of cortisol-d3 infused for determination of 24-h CPR.

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