title: Comparison of SemiQuantitative Cotinine Values Obtained by the DRI Immunoassay and Values Obtained by a Liquid Chromatography-Tandem Mass Spectrometry-Based Method: The DRI Immunoassay is Suitable for Screening Purposes Only Because Semiquantitative Values May Be Unreliable.
abstract: BACKGROUND
  DRI cotinine assay is suitable only for screening for cotinine in urine specimens. We studied the reliability of DRI cotinine semiquantitative values by comparing them with the cotinine concentration obtained with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.
  
  
  METHODS
  Semiquantitative cotinine concentrations in 39 urine specimens obtained by the DRI immunoassay were compared with cotinine concentrations obtained by LC-MS/MS.
  
  
  RESULTS
  The DRI cotinine assay consistently overestimated cotinine values obtained by the LC/MS/MS method (y = 1.1529 x + 252.24, n = 39, R2= 0.8899) indicating that semiquantitative values obtained using the DRI assay may be unreliable. However, no false-negative results were observed using the DRI assay.
  
  
  CONCLUSIONS
  DRI cotinine assay is suitable only for screening cotinine in urine specimens.
authors.affiliation: Physician's Choice Laboratory Services, Rock Hill, South Carolina, USA.
authors.forename: R Brent
authors.initials: RB
authors.lastname: Dixon
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, Texas, USA. Amitava.Dasgupta@uth.tmc.edu.
authors.forename: Amitava
authors.initials: A
authors.lastname: Dasgupta
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D003367:Cotinine / Q000652:urine*; D005260:Female; D006801:Humans; D007159:Immunologic Tests; D008297:Male; D012044:Regression Analysis; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D003367:Cotinine
keywords: DRI Assay; LC/MS/MS; cotinine; positive Bias