Simultaneous chiral separation of methylamphetamine and common precursors using gas chromatography/mass spectrometry

Abstract

Methylamphetamine, ephedrine, and pseudoephedrine were derivatized using trifluoroacetic anhydride and enantiomers of each were analyzed using gas chromatography coupled to mass spectrometry (GC/MS) fitted with a γ-cyclodextrin (Chiraldex™ G-PN) chiral column. A temperature-programmed method was developed and optimized and the results compared with those obtained using a previously published isothermal GC method applied to GC/MS analysis. Trifluoroacetylated 3-(trifluoromethyl)phenethylamine hydrochloride was used as an internal standard, and mass fragmentation patterns are proposed for all derivatives analyzed. Qualitative validation of the optimized chromatographic conditions was completed in accordance with the guidelines published by the United Nations Office on Drugs and Crime (UNODC). Under conditions of repeatability and reproducibility, the method gave relative retention times with a relative standard deviation of less than 0.02% for all six analytes of interest. This surpasses the UNODC's acceptance criteria of 2% for validation of qualitative precision. Ephedrine and pseudoephedrine are common precursors in the clandestine manufacture of methylamphetamine. Seizures of illicit methylamphetamine therefore often contain mixtures of these optically active compounds. The simultaneous enantioseparation of these compounds to produce a profile would provide valuable information to law enforcement agencies regarding the provenance of a methylamphetamine seizure.

Chiral Separation of Cathinone and Amphetamine Derivatives by HPLC/UV Using Sulfated ß‐Cyclodextrin as Chiral Mobile Phase Additive

“…In the literature, there are some articles dealing with the determination and chiral separation of cathinone, amphetamine, and related substances by high‐performance liquid chromatography (HPLC), capillary electrophoresis (CE), and gas chromatography (GC) …”

“…In the literature, there are some articles dealing with the determination and chiral separation of cathinone, amphetamine, and related substances by high-performance liquid chromatography (HPLC), 5-8 capillary electrophoresis (CE), [9][10][11][12] and gas chromatography (GC). [13][14][15] Nhujak's group reported on the chiral separation by CE using a dual cyclodextrin system consisting of ß-cyclodextrin and dimethyl-ß-cyclodextrin; the improved enantioseparation of amphetamine and drug enantiomers could be achieved with a single chiral selector. 16 For HPLC, chiral stationary phases based on crown ether showed very successful separation results; however, they are limited by the presence of a primary amine group at the analyte.…”

Regioisomeric and enantiomeric analyses of 24 designer cathinones and phenethylamines using ultra high performance liquid chromatography and capillary electrophoresis with added cyclodextrins

“…Enantiomeric separations can be achieved by specialized GC, HPLC, CE, and supercritical fluid chromatography, including the use of chiral stationary phases, or an achiral column with a chiral mobile phase, or (more traditionally) following pre-column derivatization with an optically pure chiral reagent to create diastereomers [24][25][26][27][28][29][30][31][32][33]. However, these techniques are typically highly compound selective and usually require a trial-and-error process, which can be both time consuming and expensive.…”

Simultaneous chiral analysis of amphetamine‐type stimulants and ephedrine by capillary electrophoresis coupled to time‐of‐flight mass spectrometry

“…Some articles have introduced the analytical methodologies for separating enantiomers of amphetamine-type substances (ATS), including high-performance liquid chromatography (HPLC), 5,7,8 capillary electrophoresis (CE), [9][10][11][12][13][14] gas chromatography-mass spectrometer (GC-MS), [15][16][17] ultra performance liquid chromatography-mass spectrometer (UPLC-MS), 18,19 capillary electrophoresismass spectrometry (CE-MS) 3,20-23 and nuclear magnetic resonance (NMR) spectroscopy. 24,25 Nuclear magnetic resonance spectroscopy can provide chiral information of enantiomers by adding the chiral solvating agent before detecting, while it usually needs to combine other methods (such as GC-MS) to identify an unknown seized mixture.…”