HPLC–MS/MS for Sensitive Detection of Amphetamine-Type Drugs in Water

In a recent study from scientists at Dalian Maritime University in Dalian, China, high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS) was used to help detect amphetamine-type drugs in water. The team of researchers published their findings in the Journal of Chromatography A (1).

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Amphetamine-type stimulants, such as amphetamine (AMP), methamphetamine (METH), the “ecstasy” type substances such as 3,4-methylenedioxy-methamphetamine (MDMA), and their analogues, have become a significant threat to global health and social stability. According to the United Nations’ 2023 World Drug Report, these substances rank third among prohibited drugs that lead to drug use disorders (2). Illicit production and use of these substances can lead to hazardous waste and chemicals entering bodies of water and disrupting ecosystems. Monitoring the presence of these drugs in the environment has become crucial. However, accurately quantifying these substances in environmental waters can be challenging due to ultra-low concentrations and high interference from surrounding matrices.

In this study, Pickering emulsion polymerization, which is an emulsion polymerization process where part of the colloidal stability of the produced polymer dispersion is warranted by small solid particles that are adhered to the surface of the polymer latex particles, was used to prepare magnetic surface imprinted polymer microspheres (Fe₃O₄@MIPs) (3). N-Methylphenethylamine was utilized as a surrogate template for amphetamine-type drugs, with silicon dioxide (SiO₂) and oletic acid-modified iron(III) oxide (Fe₃O₄) nanoparticles serving as stabilizers and magnetic cores, respectively.

Methacrylic acid (MAA) was chosen as the functional monomer, while ethylene glycol dimethacrylate (EGDMA) functioned as the cross-linking agent. Toluene was used as a pore-forming agent, and 2,2-azobisisobutyronitrile (AIBN) served as the initiator. N-MPEA was selected as the alternative template for MIPs synthesis. The obtained Fe₃O₄@MIPs microspheres were then utilized as adsorbents for enrichment and separation of six amphetamines from lake water and sewage samples.

Fe₃O₄@MIPs, in addition to possessing excellent dispersibility and enough magnetic properties in aqueous solutions, displayed good selectivity towards six amphetamines, with an imprinting factor ranging from 1.8 to 2.6, the scientists wrote. The adsorption kinetics closely aligned with the pseudo-second-order model, and the adsorption efficiency exceeded 80% for each amphetamine at equilibrium. These microspheres were then employed as efficient adsorbents for extracting amphetamine drugs.

Extraction parameters, including sample pH, the mass of adsorbent, and the type and volume of eluting solvent, were carefully optimized. In combination with the high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS), a selective magnetic solid-phase extraction (MISPE) method utilizing Fe3O4@MIPs was developed for the detection of six amphetamines in water samples. The limits of detection and limits of quantitation were determined to be 5.2∼23 ng L⁻¹ and 17∼77 ng L⁻¹, respectively. Recoveries for the six target drugs from lake water and sewage samples fell within the range of 87.2∼110%. Additionally, the MISPE-HPLC-MS/MS method exhibited excellent repeatability, with a precision below 8.5 % at two spiking levels. The prepared Fe₃O₄@MIPs possessed the advantages of high selectivity, straightforward preparation, facile separation and good reusability, and was highly suitable for the efficient extraction of amphetamine-type substances in complex environmental water. Altogether, these practices validated the study’s method with high accuracy and reliability, highlighting the potential of Fe₃O₄@MIPs for the analysis of amphetamines use in environmental monitoring and drug analysis.

References

(1) Tan, D.; Wang, Y.; Fan, H.; et al. Magnetic Surface-Imprinted Polymer Microspheres Coupled with HPLC-MS/MS for Sensitive Detection of Amphetamine-Type Drugs in Water. J. Chromatogr. A. 2024, 1730, 465097. DOI: 10.1016/j.chroma.2024.465097

(2) World Drug Report 2023. United Nations Office on Drugs and Crime 2023. https://www.unodc.org/unodc/en/data-and-analysis/world-drug-report-2023.html (accessed 2024-7-29)

(3) Bon, S.A.F. Pickering Emulsion Polymerization 2015. In: Kobayashi, S., Müllen, K. (eds) Encyclopedia of Polymeric Nanomaterials. Springer, Berlin, Heidelberg. DOI: 10.1007/978-3-642-36199-9_264-1