Detecting Amphetamine-Type Stimulants with Solid-Phase Microextraction

In a recent study led by scientists at Jiangsu Police Institute (Nanjing, China), solid-phase microextraction (SPME) was paired alongside a carboxyl functionalized organic-inorganic hybrid monolithic column (TMOS-co-CES) to determine harmful substances, such as amphetamine-type stimulants (ATSs). Their findings were published in the Journal of Chromatography A (1).

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Amphetamine-type stimulants (ATSs) are central nervous stimulants converted from amphetamine; this includes many derivatives, including (but not limited to) methamphetamine, ecstasy, and synthetic cathinone. These substances can make users feel euphoric and energetic by increasing the number of neurotransmitters sending messages between cells, specifically dopamine, norepinephrine, and serotonin (2). According to the scientists, ATSs have begun gradually replacing heroin, cocaine, marijuana, and other early common drugs, becoming the most popular category of new psychoactive substances (NPS) in current worldwide drug markets. Illegal NPS abuse, especially ATSs, could not only affect human physical and mental health, but also seriously endanger social order if left unchecked.

To combat illegal ATS use, the most direct and powerful clues and evidence come from fast and reliable ATS detection and identification in environmental water around drug production dens and suspects’ biological fluids. However, due to the characteristics of low content of target ATSs, complex matrix, and less volume of biological samples, it can be difficult to meet the needs of ATS detection in rare and complex samples only through gas- or liquid chromatography-mass spectrometry (GC/LC-MS) without necessary sample pretreatment. As such, it is vital to create separation materials and methods with small sample amounts, strong anti-interference ability, high sensitivity, and good extraction efficiency for selectively separating ATSs from complex and precious biological and environmental samples.

In this study, TMOS-co-CES was applied as an in-tube SPME sorbent combining with ultra-performance liquid chromatography-triple quadrupole/linear ion trap mass ((UPLC-QTRAP) spectrometer for separation and analyzation of seven typical ATSs. Substances investigated include amphetamine (AM), methamphetamine (MAM), cathinone, methcathinone, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine and 3,4-methylenedioxyethylamphetamine. Using cathinone as a representative in a computational simulation, TOMS-co-CES materials’ applicability potential to ATSs was preliminarily confirmed. With this, TMOS-co-CES could efficiently adsorb ATSs through a mixed mode of electrostatic and hydrophobic interactions under near-neutral pH conditions; this proved milder and easier-to-operate than the extraction conditions of thiol functionalized monolithic column to ATSs.

The proposed SPME method proved convenient and rapid, having the advantages of low sample consumption, mild extraction condition, high sensitivity, ideal method performance, and strong resistance to matrix interference. According to the scientists, this work was the first time a carboxyl functionalized organic-inorganic hybrid monolithic capillary column was used for separating and analyzing trace ATSs in complex environmental and biological samples. Overall, the proposed TOMS-co-CES in-tube SPME method proved reliable, having certain application feasibility for drug monitoring. This is especially the case with applications for forensic analysis and drug abuse, with potential for on-line SPME connecting directly with detectors. Further, because different types of NPS have similar structural features, physical and chemical properties, TOMS-co-CES also has potential to be used for separating other NPS, such as synthetic cannabinoids.

References

(1) Zhao, L-Y.; Qin, M.; Zheng, T.; Wu, G-P.; Lu, T. Carboxyl Hybrid Monolithic Column In-Tube Solid-Phase Microextraction Coupled with UPLC-QTRAP MS/MS for the Determination of Amphetamine-Type Stimulants. J. Chromatogr. A 2024, 1737, 465464. DOI: 10.1016/j.chroma.2024.465464

(2) Amphetamines. Cleveland Clinic 2024. https://my.clevelandclinic.org/health/drugs/23039-amphetamines (accessed 2024-1-7)