title: Rapid quantification of steroid patterns in human serum by on-line solid phase extraction combined with liquid chromatography-triple quadrupole linear ion trap mass spectrometry.
abstract: BACKGROUND
  The determination of steroids is important for the diagnosis and monitoring of endocrine diseases and infertility workup. We developed a rapid and reliable mass spectrometric method for the simultaneous quantification of steroid patterns in human serum.
  
  
  METHODS
  An on-line solid phase extraction (SPE)-liquid chromatography-triple quadrupole linear ion trap (LC-QTrap) method utilizing atmospheric pressure chemical ionization was developed. Following protein precipitation of 100 microL serum, on-line SPE and chromatographic separation was performed for 13 steroids in 1.8 min. Analytes were confirmed by the characteristic fragment patterns.
  
  
  RESULTS
  The total run time of the method was 4 min. Detection limits ranged between 0.02 microg/L (testosterone) and 9 microg/L (dehydroepiandrosterone sulfate). The method was linear up to 7000 microg/L for dehydroepiandrosterone sulfate, 500 microg/L for cortisol, 125 microg/L for 11-deoxycortisol, and 25 microg/L for aldosterone, 17-hydroxyprogesterone, progesterone, testosterone, androstenedione and beta-estradiol, respectively. Accuracy ranged between 80 and 114%. Between-day variance at three different concentration levels was <15%. Excellent correlations with immunoassays were observed for testosterone, cortisol and beta-estradiol with Pearson's correlation coefficient r=0.967, 0.963, and 0.998, respectively.
  
  
  CONCLUSIONS
  The novel on-line SPE-LC-MS/QTrap platform offers a very fast, reliable, and sensitive quantification of steroid patterns and fulfils the quality criteria for routine laboratory application.
authors.affiliation: Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig, Leipzig, Germany. uta.ceglarek@medizin.uni-leipzig.de
authors.forename: Uta
authors.initials: U
authors.lastname: Ceglarek
authors.forename: Linda
authors.initials: L
authors.lastname: Kortz
authors.forename: Alexander
authors.initials: A
authors.lastname: Leichtle
authors.forename: Georg M
authors.initials: GM
authors.lastname: Fiedler
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kratzsch
authors.forename: Joachim
authors.initials: J
authors.lastname: Thiery
mesh_terms: D000305:Adrenal Cortex Hormones / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods*; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D009862:Online Systems; D010926:Placental Hormones / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D013256:Steroids / Q000097:blood
chemical_list: D000305:Adrenal Cortex Hormones; D012739:Gonadal Steroid Hormones; D010926:Placental Hormones; D013256:Steroids