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We evaluated four commercially available methamphetamine immunoassays for their relative cross-reactivities of amphetamine analogues in human urine : Abbott TDx, Vitalab Selec tra and on-site test kits (Accusign MET, SD bioline MET). High cross- reactivities were shown at designer’s drugs such as methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA) and methylenedioxyethylamphetamine (MDEA) in all of the tested immunoassays. Methoxyphenamine, fenfluramine and phentermine were positive in TDx and Selectra, but were not positive in on-site test kits. Pseudoephedrine, norpseudoephedrine, ephedrine, norephedrine, MDMA, MDA, fenfluramine and phetermine were detected by gas chromatography/mass spectrometry(GC/MS) in false positive urines. Since the overall specificity of any of the devices was not 100%, we found it is important to confirm any positive screening test result, so we developed simultaneous determination of amphetamine analogues in urines. After alkalinization of the urine samples with 6-N NaOH, the analytes were extracted using ethyl acetate, derivatized with pentafluoropropyl anhydride (PFPA) prior at GC/MS analysis.
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