A systematic evaluation of the cross-reactivity of nine commercial enzyme-linked immunosorbent assays (ELISAs) was conducted, using 11 designer drugs.
The 2C, 2C-T, and DO series of designer drugs pose many challenges to forensic toxicology laboratories. Although these drugs are seized by law enforcement agencies throughout the United States, they are not readily detected in forensic toxicology laboratories. In the current study, cross-reactivity was measured towards 2,5-dimethoxy-4-bromophenethylamine (2C-B), 2,5-dimethoxyphenethylamine (2C-H), 2,5-dimethoxy-4-iodophenethylamine (2C-I), 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2), 2,5-dimethoxy-4-isopropylthiophenethylamine (2C-T-4), 2,5-dimethoxy-4-propylthiophenethylamine (2C-T-7), 2,5-dimethoxy-4-bromoamphetamine (DOB), 2,5-dimethoxy-4-ethylamphetamine (DOET), 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), and 4-methylthioamphetamine (4-MTA). Cross-reactivity towards the 2C, 2C-T, and DO series of psychedelic amphetamines was < 0.4 percent. Concentrations as high as 50,000 ng/mL in urine, which greatly exceed those expected in forensic case samples, were not sufficient to produce a positive result. The only substance to produce any measurable cross-reactivity was 4-MTA. Cross-reactivities of 5 and 7 percent were obtained, using four methamphetamine/MDMA directed assays, 25 and 200 percent using two amphetamine-directed assays. The absence of any measurable cross-reactivity toward the 10 2C, 2C-T, and DO psychedelic phenethylamines makes it more difficult to detect these drugs using routine screening. Consequently, laboratories that rely upon immunoassay rather than more broad-spectrum chromatographic screening techniques may fail to detect these powerful psychedelic substances. (publisher abstract modified)