A Smoking Case in which Dimethylamphetamine as a Pyrolysis Product of Methamphetamine (MA) was Detected in the Urine of MA Abuser

Abstract

There had been a smoking case in which dimethylamphetamine (DMA) and its metabolite DMA-N-oxide (DMAO) in addition to methamphetamine (MA) and amphetamine (AM), were detected in the abuser's urine. The analytical results of the confiscated leftover drug enabled us to consider that DMA detected in the abuser's urine would be the pyrolysis product formed by smoking MA. In this study, we carried out a smoking experiment based on this smoking case, and then gave the case full consideration. We heated MA hydrochloride in the range of 250°C to 350°C, in which demethylation and methylation reactions occurred mainly, with a smoke collection apparatus and a gas lighter, and trapped the generating vapor with an adsorption cartridge. AM and DMA were produced via the demethylation and methylation reactions of a methylamino group of MA. Allylbenzene, benzaldehyde, cis-β-methylstyrene, benzyl chloride and trans-β-methylstyrene were also formed as pyrolysis products. The sum of the formation ratio of DMA to the starting MA in the cartridge eluate and that in the residual materials inside the smoke collection apparatus was 4.98%. The adsorption of some pyrolyzates containing DMA on the cartridge means that these pyrolyzates can be taken into an abuser's body. The ratios of DMA to AM in the smoking experiments and the smoking case were 52.3% and 50.3%, respectively, and they were nearly equal. There will be no inconsistencies in considering that AM and DMA have been formed as pyrolysis products of MA in the smoking case, and DMA and its metabolite DMAO have been detected in the urine of this smoking abuser.