Analysis of compounds related to the synthesis of amphetamine type stimulants in wastewater and their stability

Author: Russell Fuller

  • Thesis download: available for open access on 27 Mar 2022.

Fuller, Russell, 2019 Analysis of compounds related to the synthesis of amphetamine type stimulants in wastewater and their stability, Flinders University, College of Science and Engineering

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Abstract

Illicit drug manufacture poses several health precautions to the general community as the chemicals used can be toxic and pose a risk of explosion during manufacture. This health risk is increased by the fact that the majority of clandestine laboratories are found in residential areas.

Amphetamine type stimulants (ATS) are the most common substances synthesised in clandestine laboratories both worldwide and in Australia. They can be synthesised via numerous methods including the: hypophosphorous, red phosphorous, Nazi/Birch and 1-phenylpropan-2-one method for synthesising methamphetamine, many of which produce route specific impurities. To try and avoid detection, clandestine waste is generally disposed of using domestic drainage, domestic garbage, burying or in landfill. Disposal of clandestine waste material into the municipal wastewater system may provide a valuable information source for law enforcement.

Currently wastewater has been analysed for illicit drug metabolites to gain estimates for the amount of illicit drug consumption. These estimates are in good agreement with population surveys and have the advantage of being time efficient and not relying on information from the consumers themselves, which may be misleading. With the recent development of new designer drugs, the consumer may be unaware or mislead about which drugs they are consuming making population surveys less reliable.

The motivation of this thesis was to fill this gap in knowledge by developing a method for the extraction and analysis of compounds relates to the production of common amphetamine type stimulants and to investigate the feasibility of wastewater analysis for their detection.

To achieve this goal compounds related to the synthesis of amphetamine synthesis namely: benzaldehyde, 1-phenylpropan-2-one, 4-methoxybenzladehyde, safrole, piperonal, ephedrine, pseudoephedrine, amphetamine and methamphetamine were used to develop a solid phase extraction method. A high recovery of each compound was achieved with the lowest recovery occurring for benzaldehyde (79 %). In addition, a liquid chromatography mass spectrometry (LCMS) method employing multiple reaction monitoring (MRM) was developed along with a gas chromatography mass spectrometry (GCMS) method operated in both scan and selected ion monitoring (SIM) modes for the analysis of the wastewater extracts.

In addition to investigating the presence of these targeted compounds in wastewater, the stability of: benzaldehyde, 1-phenylpropan-2-one, 4-methoxybenzaldehyde, safrole and piperonal in wastewater was tested at both room temperature and at storage conditions; pH = 2 adjusted at - 20 ℃. This was achieved by spiking wastewater samples from several South Australian wastewater treatment plants (WWTP) with each compound prior to extraction and GCMS analysis.

The stability results showed that extreme care must be taken when analysing wastewater for these compounds particularly if not stored appropriately. Benzaldehyde was shown to be the least stable having a half-life of only 5.4 ± 0.2 days. The stability of all compounds increased significantly for the samples stored in the freezer with benzaldehyde again being the least stable having a half-life of 23 ± 1 days. In addition, some of the degradation products were identified by injection of a degraded wastewater sample which was spiked with a high concentration of the targeted compounds. This test showed the presence of benzyl alcohol, benzoic acid, 4-methoxybenzene methanol, piperonal alcohol, 4-methoxybenzoic acid, piperonylic acid and 1,3-diphenylpropan-2-one.

Wastewater samples were obtained from several Australian wastewater treatment plants (WWTP). These samples were filtered, pre-concentrated using SPE and were analysed using the developed GC-MS and LC-MS methods. In addition to the targeted compounds the presence of the degradation products identified in the stability experiments was also investigated. The only compounds routinely found in the wastewater extracts were benzaldehyde and benzoic acid, compounds which are expected to be present in wastewater from sources other than the illicit manufacture of amphetamine type stimulants. The non-detection of the other substances may be a result of sampling during periods where a dumping event may not have occurred or that the concentration of these substances was too low for the detection limits of the GCMS method. For this reason, the feasibility for the use of wastewater analysis for the detection of these compounds cannot be confirmed as the presence is highly dependent on the batch nature of illicit drug production.

Analysis of SPE samples via LCMS showed the ability of wastewater analysis for obtaining consumption estimates of ATS. A wastewater sample from Coombabah wastewater treatment plant was analysed and based on an external calibration method found to have methamphetamine, pseudoephedrine and Amphetamine present at levels of 175, 995 and 9.0 mg/day/1000 people respectively.

Keywords: wastewater, amphetamine type stimulants, stability

Subject: Chemistry thesis

Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Science and Engineering
Supervisor: G. Stewart Walker