title: Assessing analytical specificity in quantitative analysis using tandem mass spectrometry.
abstract: OBJECTIVE
  The necessity of confirmation of compound identity in quantitative analysis is well recognized for methods utilizing single mass spectrometry detection but is not commonly addressed for applications utilizing multiple-stage mass spectrometry (MSn). For MSn detection, no commonly accepted rules for assessment of analytical specificity in quantitative analyses have been established to date.
  
  
  METHODS
  To assure compound identity, we evaluated approaches based on monitoring multiple mass transitions of a target compound followed by comparison of the branching ratios of the mass transitions.
  
  
  RESULTS
  Monitoring multiple mass transitions along with evaluation of the ratio of their relative intensities allows the analyst to distinguish the target analyte from interferences in quantitative analysis. The strategy and the acceptance criteria are compound and method specific and should be established during the method development and validation.
  
  
  CONCLUSIONS
  The certainty of analyte identity is very important in quantitative analysis using MSn detection; methods to verify analyte identity should be used in all critical applications.
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT 84108, USA. kushnmm@aruplab.com
authors.forename: Mark M
authors.initials: MM
authors.lastname: Kushnir
authors.forename: Alan L
authors.initials: AL
authors.lastname: Rockwood
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Nelson
authors.forename: Bingfang
authors.initials: B
authors.lastname: Yue
authors.forename: Francis M
authors.initials: FM
authors.lastname: Urry
mesh_terms: D003348:Cortisone / Q000032:analysis; D006801:Humans; D007166:Immunosuppressive Agents / Q000032:analysis; D007554:Isotopes; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards*; D008764:Methylmalonic Acid / Q000032:analysis; D012016:Reference Values; D012680:Sensitivity and Specificity; D020123:Sirolimus / Q000032:analysis; D013739:Testosterone / Q000032:analysis
chemical_list: D007166:Immunosuppressive Agents; D007554:Isotopes; D013739:Testosterone; D008764:Methylmalonic Acid; D003348:Cortisone; D020123:Sirolimus