Case Study

Rapid screening of street drugs bybenchtop NMR
The spread of illicit drugs has become a global problem, not only causing direct harm to people's physicaland mental health, but also seriously affecting social and economic development. In addition to traditional
drugs, many new psychoactive substances (NPS) have appeared in recent years, and they are becoming
increasingly popular. New psychoactive substances are also known as "designer drugs" or "laboratory drugs".
To avoid prosecution, criminals artificially design and modify the chemical structure of controlled drugs toobtain new types with effects similar to or even stronger than those of the controlled drugs. Due to the "newstructure" of these substances, some traditional detection methods have become invalid, presenting greatchallenges to the drug prevention and control work of the whole society.

Fast drug screening without expert
operators
Nuclear Magnetic Resonance (NMR) technology canprovide information on the connection of chemicalmolecular frameworks. It is the most direct tool forcompound structure identification and can be used as aneffective means to detect and identify new psychoactive
substances. However, because traditional high-field
superconducting NMR spectrometers have special
requirements for operation and location, and becauseof the high cost of instrument use and maintenance,
the application of NMR technology in rapid street drug
screening is limited. In response to the above problems,
Oxford Instruments has provided a new benchtop NMR
solution for rapid drug identification. Oxford Instruments’
X-Pulse benchtop NMR spectrometer uses rare earth
permanent magnets, does not require liquid nitrogen,liquid helium or other refrigerants, is simple to operate andeasy to maintain, and can quickly collect NMR spectra ofsuspicious drug samples.

1 © Oxford Instruments plc, 2021.

Figure 1. One-dimensional 1H spectra of three methcathinones

The supporting drug database enables rapid analysis
and automatic comparison of the spectra of unknown
samples against the spectra of known references. The
samples can be tested on the X-Pulse after simple
dissolution and processing, with the spectra collected
automatically. Comparison and score matching is carriedout against the built-in special drug database (which canbe updated as new compounds are discovered) to give thebest recommended match of possible substances. Evenfor a mixture of multiple drug substances, the instrument
can automatically fit spectra against the drug fingerprint
library and suggest possible combinations of mixed drugs,
so that illicit drugs cannot be disguised. For most samples,fully automatic data collection, processing and analysis
can usually be completed within 5-20 minutes.

Figure 1 shows the one-dimensional 1H spectrum of threemethcathinones on a 60 MHz X-Pulse. The molecular
structures of these three compounds are very similar,
with only one fluorine atom or slight difference in thesubstitution position on the benzene ring. In the upfield"type identification area" of the chemical shift of thespectrum (for example, 0.5-2.0 ppm), the three have split
double peaks, indicating that they belong to the same
type of substance. In the downfield “fingerprint area” ofthe chemical shift of the spectrum (such as 7.0-9.0 ppm),
the three show their own unique peak characteristics, thus
permitting chemical structure differentiation. By patternmatching the "type identification area" and "fingerprintarea" of the unknown substance with the databasestandard sample spectrum, the composition and structureof the unknown substance can be determined.

Amphetamine Analog
Take methcathinone as an example. Methcathinone isan analog of amphetamine and belongs to the strictly
controlled Class I psychotropic drugs. It can cause acutehealth problems and permanent brain damage, and insevere cases can be life-threatening.

© Oxford Instruments plc, 2021. 2Sample Match Criteria

Quantity

PercentageTotal number of samples analysed

432

Unable to verify (GC-MS does not produce peaks)

13

3.0%

No API or admixtures

30.7%

Cannot match

40.9%

Correct match (single component sample)

374

86.6%

Correct match (two-component sample)

13

3.0%

Partial matching (two-component or multi-component samples)

25

5.8%

Verification of samples containing API or admixtures

416

Exact match

387

93.0%

Exact + partial match

412

99.0%

Table 1. Analysis results of a batch of suspicious samples

A batch of suspicious samples seized by publicsecurity agencies was analysed by X-Pulse and gas
chromatography-mass spectrometry (GC-MS) at the sametime. The results are shown in Table 1. The total number ofsamples analysed was 432, of which 13 (3.0%) could not
be verified by NMR due to there being no GC-MS peaks,and 3 (0.7%) contained no active ingredients (API) oradmixtures. Among the remaining 416 samples that wereconfirmed to contain API or admixtures, 387 (93.0%) of theNMR and GC-MS test results were matched exactly. On
this basis, if the partially matched samples are added, thetotal number reached 412 (99.0%). Of equal importance,
no false positives were found. This data demonstrates
that X-Pulse can detect and identify street drugs with highaccuracy and reliability.

3 © Oxford Instruments plc, 2021.

(a)Identifying street drugs - data for judicial
enforcement
Through comparison and matching with the X-Pulse drug
database, it was found that more than 400 questionablesamples contained a variety of different drugs. Amongstreet drugs consisting of single-component compounds,
the most often detected were ecstasy (MDMA), cocaine
and ketamine; in the two-component mixture samples,
cocaine/levamisole, cocaine/benzocaine, and otheradmixtures were mainly found (Figure 2). The results canprovide valuable references for public security judicial
identification agencies to understand the types andprevalence of local drugs, and to formulate corresponding
control strategies and action plans.

References:(b)[1] Antonides LH et al., Rapid Identification of Novel
Psychoactive and Other Controlled Substances Using
Low-Field 1H NMR Spectroscopy, ACS Omega. 2019,
4: 7103-7112[2] Mewis R et al., Quantification of MDMA in seized tablets
using benchtop 1H NMR spectroscopy in the absence ofinternal standards, Forensic Chemistry, 2020, 20: 100263

Figure 2. Types and quantities of street drugs detectedby X-Pulse(a) One-component compound; (b) Two-component mixture [1]Visit nmr.oxinst.com© Oxford Instruments Industrial Products Ltd trading as Oxford Instruments Magnetic Resonance,
2021. All rights reserved. Do not reproduce without permission. Part no: MR/227/0121© Oxford Instruments plc, 2021. 4