title: The determination of urinary free and conjugated cortisol using UPLC-MS/MS.
abstract: BACKGROUND
  To develop an UPLC-MS/MS method to replace the in-house immunoassay for the analysis of urinary cortisol.
  
  
  RESULTS
  Cortisol was extracted from human urine by ethyl acetate and analyzed on a Waters ACQUITY TQD system using a BEH C18 column. Linear calibration curves were generated over the range of 27.6 to 1380 nmol/l and exhibited consistent linearity and reproducibility with a correlation coefficient greater than 0.9950. Intra-day coefficients of variation were between 3.74 and 5.10% and inter-day coefficients of variations were between 4.22 and 6.73%. The extraction recovery of cortisol was greater than 83%.
  
  
  CONCLUSIONS
  An accurate, rapid and robust UPLC-MS/MS method for the determination of urinary cortisol has been developed and validated. With a lower flow rate (0.4 ml/min), a shorter running time per sample and a simple and cost-effective sample preparation, this method is a desirable option for clinical laboratories.
authors.affiliation: Department of Chemistry, BC Biomedical Laboratories, 7455-130th Street, Surrey, British Columbia, Canada. DMing@bcbio.com
authors.forename: Dong Sheng
authors.initials: DS
authors.lastname: Ming
authors.forename: John
authors.initials: J
authors.lastname: Heathcote
authors.forename: Arun
authors.initials: A
authors.lastname: Garg
authors.forename: Jim
authors.initials: J
authors.lastname: Darbyshire
authors.forename: Erna
authors.initials: E
authors.lastname: Eagleston
authors.forename: Teri-Lynn
authors.initials: TL
authors.lastname: Bajkov
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D006854:Hydrocortisone / Q000652:urine*; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*
chemical_list: D006854:Hydrocortisone