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Development of a urinary free cortisol assay using solid-phase extraction-capillary electrophoresis.
L V Rao1, J R Petersen, M G Bissell
1Department of Pathology, University of Texas Medical Branch, Galveston, 77555-0551, USA.
Summary
This study introduces a rapid SPE-CE method for measuring urinary free cortisol (UFC), improving diagnostic accuracy for adrenal disorders. The new technique offers faster, more reliable results compared to traditional methods.
Area of Science:
- Clinical Chemistry
- Analytical Chemistry
- Endocrinology
Background:
- Urinary free cortisol (UFC) measurement is crucial for diagnosing excess adrenal cortisol production.
- Existing RIA and HPLC methods for UFC analysis are time-consuming, expensive, and prone to interference from cortisol metabolites.
Purpose of the Study:
- To develop and validate a rapid Solid-Phase Extraction coupled with Capillary Electrophoresis (SPE-CE) method for UFC analysis.
- To improve the sensitivity, specificity, and efficiency of UFC determination in clinical practice.
Main Methods:
- UFC was concentrated using C18 SPE cartridges, with optimized washing and elution steps using acetonitrile-SDS and acetone.
- Capillary Electrophoresis (CE) was performed on a Beckman P/ACE 5010 with UV detection at 254 nm.
- Validation involved assessing recovery, detection limits, and interference from other urinary components.
Main Results:
- The SPE-CE method achieved a rapid extraction time of 10-15 minutes with high cortisol recovery (89-94%).
- Detection limits for UFC were significantly improved to 10 microg/l with SPE, compared to 500 microg/l without.
- The method demonstrated robustness, with no significant interferences from proteins or other urinary metabolites.
Conclusions:
- The developed SPE-CE method provides a feasible, rapid, and reliable approach for UFC detection.
- This technique enhances sample handling capacity and diagnostic accuracy for adrenal disorders.