Indirect chiral separation of crystal methamphetamine seized in Saudi Arabia using GC-MS

ABSTRACT

In the last decade, worldwide illegal production and consumption of methamphetamine (MA) has dramatically increased. MA is chiral and its two enantiomers have different biological properties, the S isomer having higher stimulating and addictive effects and therefore important to determine the enantiomeric ratio in drug seizures. The chiral separation and determination of R and S-MA may be used for characterization of the seized samples and elucidation of the illicit method of preparation. The present article aims to investigate the enantiomeric distribution of R and S methamphetamine in a series of seized samples. The enantioseparation was achieved first by derivatization of MA using L-TPC followed by separation of the resulting diastereomers using GC-MS. The optimized chromatographic method allowed baseline separation of the peaks with a resolution parameter of 2.16. While the total concentration of methamphetamine in the seized samples was between 15.09 and 213.20 mg/g, all investigated samples showed the presence of both R and S enantiomers, with a higher content of S-MA. The enantiomeric excess (ee%) was calculated to characterize each sample, the obtained values were in the range 55.27–92.38%. The results demonstrated that the seized samples originated from different batches and most likely from a stereospecific synthetic route.

Graphical Abstract

KEYWORDS:

• Methamphetamine enantiomers
• chiral separation
• derivatization
• L-N-(trifluoroacetyl)prolyl chloride (L-TPC)
• seized samples

Highlights

Seized methamphetamine crystal

Derivatization of methamphetamine with L-TPC

Chiral resolution of methamphetamine diastereomers with GC-MS

Enantiomeric excess of S-methamphetamine

S-methamphetamine higher in all seized samples

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Credit author statement

A. Dhabbah and A. Alawi carried out the visualisation, curation and wrote the original draft with reviewing and editing.

A. Dhabbah and Y. Badjah achieved the conceptualization, established the methodology.

A. Alawi, W. AlAngari, S. Ben‐Jaber and M. bin Jassas carried out the data collection, investigation and validation.

C. Morrison revised and edited whole document.