One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.
Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs.
ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108-1221, USA stephanie.marin@aruplab.com.
Stephanie J
SJ
Marin
ARUP Laboratories, Inc., 500 Chipeta Way, Salt Lake City, UT 84108-1221, USA Department of Pathology, University of Utah Health Science Center, Salt Lake City, UT, USA.
Kelly
K
Doyle
University of California, Berkeley, CA, USA.
Annie
A
Chang
National Institute on Drug Abuse, Baltimore, MD, USA Department of Sciences, City University of New York, John Jay College, New York, NY, USA.
Marta
M
Concheiro-Guisan
National Institute on Drug Abuse, Baltimore, MD, USA.
Marilyn A
MA
Huestis
ARUP Laboratories, Inc., 500 Chipeta Way, Salt Lake City, UT 84108-1221, USA Department of Pathology, University of Utah Health Science Center, Salt Lake City, UT, USA.
Kamisha L
KL
Johnson-Davis
D000661:Amphetamine / Q000737:chemistry* / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods*; D003429:Cross Reactions; D005189:False Positive Reactions; D006801:Humans; D007118:Immunoassay; D013058:Mass Spectrometry / Q000379:methods*; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000737:chemistry* / Q000652:urine*; D011933:Reagent Kits, Diagnostic / Q000592:standards
D011933:Reagent Kits, Diagnostic; D000661:Amphetamine; D018817:N-Methyl-3,4-methylenedioxyamphetamine