Contribution of thermal desorption and liquid–liquid extraction for identification and profiling of impurities in methamphetamine by gas chromatography–mass spectrometry

Abstract

Impurity profiling of methamphetamine (MA) using thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS) was examined. Using TD/GC-MS, impurities were extracted and separated under various conditions. Optimal chromatograms were obtained when a 20 mg MA sample was extracted at 120˚C for 3 min using a TD instrument, followed by separation of the extracts using a nonpolar capillary column coated with (5%-phenyl)-methylpolysiloxane.MA samples from nine different batches were analyzed under optimized conditions.Compounds related to the structure of MA, such as benzaldehyde, benzyl alcohol, amphetamine, cis-and trans-1,2-dimethyl-3-phenylaziridine, dimethylamphetamine, and N-acetylephedrine, were detected in the chromatograms without any laborious extraction procedure. Compounds such as ethanol, diethyl ether, and acetic acid, which are considered reagents and solvents for MA synthesis, were also detected in some of the chromatograms. The numbers and intensities of the peaks detected were different among the samples. Impurity profiling of MA using TD was compared with that using liquid-liquid extraction (LLE). Better reproducibility of peak areas was obtained using LLE, whereas higher intensities and numbers of peaks were detected using TD. Solvents were 2 extracted more effectively using TD. The nine batches of MA were classified using both extraction procedures. The nine batches were divided roughly into two groups using data from LLE. Subsequently, the groups were classified in detail using data from TD.TD can be used to provide supplemental information for LLE, and the combination of these extraction methods can be helpful for impurity profiling of MA.

Characterisation of aqueous waste produced during the clandestine production of amphetamine following the Leuckart route utilising solid‐phase extraction gas chromatography–mass spectrometry and capillary electrophoresis with contactless conductivity detection

“…The extended list includes 25 different compounds identified in the samples and also the corresponding retention times, structures, and mass spectral peaks. This compound (F) was also found by others in methamphetamine31,32,[34][35][36] and in amphetamine 12,37 samples. The aqueous waste should, in general, contain the organic compounds that are contained in the corresponding organic phases that are separated and used for following synthesis steps.…”

“…This similar peak pattern was evidence, that the used SPE procedure was capable to extract the various organic compounds from the aqueous waste samples which were identified as following:Benzyl alcohol (A) is an impurity which was up to now only reported in methamphetamine samples 31,32. The extended list includes 25 different compounds identified in the samples and also the corresponding retention times, structures, and mass spectral peaks.…”

“…An Benzyl alcohol (A) is an impurity which was up to now only reported in methamphetamine samples. 31,32 Of note is that Stojanovska et al 33 reported that benzyl alcohol was found in methamphetamine samples that also contained 1-phenyl-2-propanol (F) which is, according to them, indicative of these samples being synthesised via the reductive amination route. This compound (F) was also found by others in methamphetamine 31,32,[34][35][36] and in amphetamine 12,37 samples.…”

“…Each is represented by a unique letter that is also used in the following paragraphs. Dimethoxymethylbenzene (B) was not reported as an impurity up to now and is likely an artefact that is formed in the GC instrument from benzaldehyde, which was found in ATS samples before,31,32,37,38 and the GC solvent methanol. The pH of the aqueous phase has an important influence on this equilibrium since acidic compounds will show an increased solubility in alkaline waste samples.…”

Development of a Liquid-Liquid Extraction Procedure for the Analysis of Amphetamine in Biological Specimens by GC-FID

“…A number of publications have appeared addressing extracting solvents such as diethyl ether [4,5], ethyl acetate [6,7], 1-chlorobutan [8,9] and various mixtures of solvents [10][11][12][13] that were used in the isolation of amphetamines from biological samples by LLE, but there is no information about the recovery of amphetamines. Although there is information about the influence of the pH on the recovery of amphetamines in profiling of amphetamine impurities using LLE [14,15], this has not been investigated in the extraction of amphetamines from biological samples.…”