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- Title
A fluorimetric assay for cortisol.
- Authors
Appel, Daniel; Schmid, Rolf D.; Dragan, Calin-Aurel; Bureik, Matthias; Urlacher, Vlada B.
- Abstract
A simple, rapid and sensitive fluorimetric assay for the quantitative determination of cortisol is reported. The assay is based on the formation of a fluorescent dye when cortisol is incubated with a mixture of sulfuric acid and acetic acid. The fluorescence spectrum recorded for the resulting dye shows a maximum extinction at 475 nm and a maximum emission at 525 nm. The solvent 2-methyl-4-pentanone was used for extraction and was found to act as a fluorescence amplifier. A limit of detection of 2.7 μM was achieved, making it possible to forego solvent evaporation. The assay suffers minor interference from 11-deoxycortisol which exhibits low fluorescence at λ ex: 460 nm; λ em: 505 nm. Typical standard deviations were below 4%. We validated the assay using a biotransformation with recombinant Schizosaccharomyces pombe which regioselectively hydroxylates 11-deoxycortisol to cortisol. The method described herein is suitable for preliminary screening of microorganisms capable of steroid hydroxylation.
- Subjects
HYDROCORTISONE; SCHIZOSACCHAROMYCES pombe; FLUORIMETRY; GLUCOCORTICOIDS; SCHIZOSACCHAROMYCES
- Publication
Analytical & Bioanalytical Chemistry, 2005, Vol 383, Issue 2, p182
- ISSN
1618-2642
- Publication type
Article
- DOI
10.1007/s00216-005-0022-9