title: Recent advances in the assessment of the ratios of cortisol to cortisone and of some of their metabolites in urine by LC-MS-MS.
abstract: A previously reported method for the assessment of the ratio of tetrahydrocortisol (THF) + allo-tetrahydrocortisol (A-THF) to tetrahydrocortisone (THE) by HPLC-MS-MS has been significantly improved, in order to increase either ruggedness and reliability. That was achieved by the introduction of an on-line sample cleanup stage, which made use of a perfusion column as a solid phase microextraction (SPE) cartridge. The set of analytes was expanded, by introducing cortisol and cortisone, whose ratio supply additional diagnostic information. The response factors of both THF and A-THF has been checked, resulting almost identical, as well as the influence of the matrix on the calibration curves which, although different for water and urine, had similar effect on the ratios of interest. As a consequence, the calibration solutions can be prepared in pure water. The influence of several different storage procedures has also been tested, resulting in no substantial effect on the final result. Finally, the improved method has been used to run real samples from healthy volunteers, with satisfactory results.
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Saba
authors.forename: Andrea
authors.initials: A
authors.lastname: Raffaelli
authors.forename: Adamasco
authors.initials: A
authors.lastname: Cupisti
authors.forename: Antonella
authors.initials: A
authors.lastname: Petri
authors.forename: Claudio
authors.initials: C
authors.lastname: Marcocci
authors.forename: Piero
authors.initials: P
authors.lastname: Salvadori
mesh_terms: D000328:Adult; D000368:Aged; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D003348:Cortisone / Q000378:metabolism / Q000652:urine*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism / Q000652:urine*; D008297:Male; D008875:Middle Aged; D052617:Solid Phase Microextraction / Q000295:instrumentation / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult
chemical_list: D003348:Cortisone; D006854:Hydrocortisone