title: Improved identification of multiple drugs of abuse and relative metabolites in urine samples using liquid chromatography/triple quadrupole mass spectrometry coupled with a library search.
abstract: BACKGROUND
  Although two multiple reaction monitoring (MRM) transitions per compound are used for identification performed using liquid chromatography/triple quadrupole mass spectrometry (LC/QqQ-MS/MS), differences in identification criteria among several regulations may lead to misidentification. We demonstrated that the use of two MRM transitions and product ion spectra improves compound identification.
  
  
  METHODS
  The scan cycle time was reduced using time-scheduled MRM (tMRM), data-dependent product ion scanning, and dynamic exclusion. The quantification and identification performance for 13 drugs of abuse and their metabolites were evaluated.
  
  
  RESULTS
  Deuterated internal standards compensated for ion suppression. All analytes exhibited intra- and interday precision <12.11%, accuracy of -10.31% to +10.10%, and no carryover. The LC/QqQ-MS/MS and reference gas chromatography/MS methods were equally precise, accurate, and specific. Several regulatory organizations include two MRM transitions, their ratio, and retention time as identification criteria. In 28 samples, the relative ion ratio variation was >10% and product ion spectral matches with >94% probabilities improved drug and metabolite identification.
  
  
  CONCLUSIONS
  The LC/QqQ-MS/MS method is a comprehensive assay in which tMRM and the product ion scan are combined in a single run by using a QqQ mass analyzer to simultaneously quantify amphetamine, ketamine, morphine, and their relative metabolites in urine. The proposed method can be applied in forensic science.
authors.affiliation: Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan; Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan; Center for Drug Analysis, Tzu Chi University, Hualien, Taiwan.
authors.forename: Huei-Ru
authors.initials: HR
authors.lastname: Lin
authors.forename: Chao-Chuan
authors.initials: CC
authors.lastname: Liao
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Lin
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D016208:Databases, Factual; D006801:Humans; D013287:Illicit Drugs / Q000737:chemistry / Q000652:urine*; D057230:Limit of Detection; D016014:Linear Models; D015813:Substance Abuse Detection / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D013287:Illicit Drugs