Designer psychostimulants are known by recreational drug users to produce a complex array of adrenergic and hallucinogenic effects. Many of these drugs are not targeted during routine toxicology testing and as a consequence, they are rarely reported. The purpose of this study was to develop a procedure for the detection of 15 psychostimulants in urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS), specifically 2,5-dimethoxy-4-bromophenethylamine (2C-B), 2,5-dimethoxy-4-chlorophenethylamine (2C-C), 2,5-dimethoxy-4-methylphenethylamine (2C-D), 2,5-dimethoxy-4-ethylphenethylamine (2C-E), 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-chloroamphetamine (DOC), 2,5-dimethoxy-4-ethylamphetamine (DOET), 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), and 4-methylthioamphetamine (4-MTA). Analytical recoveries using solid-phase extraction were 64-92% and the limit of detection was 0.5 ng/mL for all drugs except 2C-B (1 ng/mL). The assay was evaluated in terms of analytical recovery, precision, accuracy, linearity, matrix effect, and interferences. The technique allows for the simultaneous detection of 15 psychostimulants at sub-ng/mL concentrations.

Exposure of proteins to different oxidants is accompanied by light emission from decaying electronically excited intermediates. One of our goals is to identify what amino acid side chains are responsible for this process. In a previous study we showed that exposure of 1mg/ml BSA to 1 mM H2O2/200 μM FeCl2 (a source of hydroxyl radical) resulted in modifications of H42, M111, P120, F251, F353, P596, and M571. In order to determine whether these modifications are random or specific, we repeated the experiment but changed the concentrations of ferrous iron (0, 100 μM and 1 mM), H2O2 (100 μM and 1 mM). Some experiments were run in the presence of ascorbic acid to maintain iron in the reduced state (0.1 mM or 1 mM). The samples were digested and screened through a Q‐Tof Ultima ™ (MS Waters, Micromass, Beverly, MA) at a low flow state of 1 μl/min. Samples that showed proper sample material were sent to the LTQ Orbitrap (Thermo Electron, San Jose, CA) for a reliable and higher resolution search for sequence coverage. Data was analyzed with an in‐house copy of Mascot ™, an internet‐based search engine. The results showed consistent oxidation of specific side chains (F51, C58, H63, F73, F172, F353, M469 and M571). As the concentration of oxidants increased, we observed an increase in non specific modification.Conclusionalthough hydroxyl radical is a very powerful oxidant, it tends to attack specific amino acids in proteins. Another possibility is that these amino acids become associated iron, and therefore become the nearest targets for hydroxyl radicals formed during the decomposition of H2O2.