Analysis of N,N‐dimethylamphetamine in wastewater – a pyrolysis marker and synthesis impurity of methamphetamine

Frederic Been, Jake O'Brien, Foon Yin Lai, Marie Morelato, Peter Vallely, Jenny McGowan, Alexander L. N. van Nuijs, Adrian Covaci, Jochen F. Mueller

The increased availability of high purity crystalline methamphetamine (MA) in Australia raised concerns because of high dosages and its potential consumption through inhalation. The present work investigates the possibility of using wastewater levels of N,N-dimethylamphetamine (DMA), a pyrolysis by-product formed during smoking, as an indirect indicator of MA smoking. A dedicated liquid chromatography time-of-flight mass spectrometry (LC-QTOF-MS) method was setup to detect and quantify DMA in the wastewater samples. Wastewater samples were collected from eight locations across Australia during the period 2011-2016. Data about the abundance of DMA in MA seizures as well as in residues from drug paraphernalia (i.e., pipes) were obtained from forensic laboratories in Australia. DMA/MA ratios measured in wastewater ranged from 0.0001 to 0.09 (median 0.007). DMA/MA ratios in bulk seizures are generally below 0.0025, with a median value of 0.0004, whilst residues in paraphernalia ranged from 0.031 to 3.37. DMA/MA ratios in wastewater decreased in the investigated period, in parallel to an increase in MA loads. Furthermore, wastewater analyses highlighted a strong positive correlation between DMA/MA ratios and per capita MA use (Pearson's correlation ρ= 0.61, p-value < 0.001). Nonetheless, geographical specificities could be highlighted between the investigated locations. The obtained data could help authorities detect hot spots of drug use as well as to plan specific intervention campaigns to tackle the issue. In future, simultaneous analysis of DMA and MA in both wastewater and seizures could improve our understanding about MA use and its consumption patterns.