title: Evaluation of two enzyme immunoassays for the detection of the cocaine metabolite benzoylecgonine in 1,398 urine specimens.
abstract: BACKGROUND
  Benzoylecgonine (BE) is the primary urinary metabolite of cocaine. Two enzyme immunoassays were evaluated for the detection of BEin urine with a 300 ng/ml cutoff: the DRI® Cocaine Metabolite Assay and Lin-Zhi International's (LZ) Cocaine Metabolite Enzyme Immunoassay.
  
  
  METHODS
  This study involved 1,398 urine specimens from criminal justice and pain management programs. Gas chromatography/mass spectrometry (GC/MS) data were obtained for presumptive positives, and for negative urine specimens yielding responses significantly above the negative control.
  
  
  RESULTS
  Approximately 46% (644) of the specimens yielded positive results by DRI, and 47% (664) were positive by LZ. One specimen screened positive with both assays but was found to have a nondetectable BE concentration by GC/MS, indicating one false positive for each assay. Twenty-one specimens yielding negative DRIresults contained BEabove 300 ng/ml, and 29 specimens yielded false negatives with the LZassay. Therefore, the overall agreement between both immunoassays and GC/MSresults was 98%. Assay sensitivity was 0.968 (DRI) and 0.958 (LZ); the selectivity for both assays was 0.999. Urine specimens containing cocaine, additional cocaine metabolites, and other drugs were also tested. No cross-reactivity was observed.
  
  
  CONCLUSIONS
  Both the DRIand LZassays provide a precise, reliable method for the routine detection of BEin urine.
authors.affiliation: Department of Forensic Science, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Carney
authors.forename: Carl E
authors.initials: CE
authors.lastname: Wolf
authors.forename: Lisa
authors.initials: L
authors.lastname: Tarnai-Moak
authors.forename: Alphonse
authors.initials: A
authors.lastname: Poklis
mesh_terms: D003042:Cocaine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000652:urine; D005188:False Negative Reactions; D005189:False Positive Reactions; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods* / Q000592:standards
chemical_list: C005618:benzoylecgonine; D003042:Cocaine