The Application of a Desktop NMR Spectrometer in Drug Analysis

Smart Multiplex Point-of-Care Platform for Simultaneous Drug Monitoring

Recently, illicit drug use has become more widespread and is linked to problems with crime and public health. These drugs disrupt consciousness, affecting perceptions and feelings. Combining stimulants and depressants to suppress the effect of drugs has become the most common reason for drug overdose deaths. On-site platforms for illicit-drug detection have gained an important role in dealing, without any excess equipment, long process, and training, with drug abuse and drug trafficking. Consequently, the development of rapid, sensitive, noninvasive, and reliable multiplex drug-detecting platforms has become a major necessity. In this study, a multiplex laser-scribed graphene (LSG) sensing platform with one counter, one reference, and three working electrodes was developed for rapid and sensitive electrochemical detection of amphetamine (AMP), cocaine (COC), and benzodiazepine (BZD) simultaneously in saliva samples. The multidetection sensing system was combined with a custom-made potentiostat to achieve a complete point-of-care (POC) platform. Smartphone integration was achieved by a customized application to operate, display, and send data. To the best of our knowledge, this is the first multiplex LSG-based electrochemical platform designed for illicit-drug detection with a custom-made potentiostat device to build a complete POC platform. Each working electrode was optimized with standard solutions of AMP, COC, and BZD in the concentration range of 1.0 pg/mL-500 ng/mL. The detection limit of each illicit drug was calculated as 4.3 ng/mL for AMP, 9.7 ng/mL for BZD, and 9.0 ng/mL for COC. Healthy and MET (methamphetamine) patient saliva samples were used for the clinical study. The multiplex LSG sensor was able to detect target analytes in real saliva samples successfully. This multiplex detection device serves the role of a practical and affordable alternative to conventional drug-detection methods by combining multiple drug detections in one portable platform.

Benchtop nuclear magnetic resonance spectroscopy in forensic chemistry

Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique well known for its ability to elucidate structures and analyse mixtures and its quantitative nature. However, the cost and maintenance of high field NMR instruments prevent its widespread use by forensic chemists. The introduction of benchtop NMR spectrometers to the market operating at 40-80 MHz have a small footprint, are easy to use and cost much less than high field instruments, which makes them well suited to meet the needs of forensic chemists. These modern low field spectrometers are often capable of running multiple nuclei including ¹ H, ¹³ C, ¹⁹ F and ³¹ P; 2D NMR experiments and advanced experiments such as solvent suppression and diffusion-ordered spectroscopy (DOSY) are possible. This has resulted in a number of publications in the area of forensic chemistry using benchtop NMR spectroscopy in the last 5 years that was previously missing from the literature. This mini review summarises this research including examples of benchtop NMR being used to identify and quantify compounds relevant to forensics and some advanced methods that may be used to overcome some of the limitations of these instruments for forensic analysis. Further validation and automation are likely required for widespread uptake of benchtop NMR in industry; however, it has been demonstrated as a useful complement to other analytical techniques commonplace of forensic laboratories.

Identification of seven psychedelic 2,5-dimethoxy-phenylethyl-amine-based designer drugs via benchtop 1 H nuclear magnetic resonance spectroscopy

The dissemination of spectral information of new psychoactive substances (NPS) acquired on benchtop nuclear magnetic resonance (NMR) spectrometers is of high importance considering the emerging application of such portable and accessible instruments in forensic analyses. Seven members of the 2C-X series (2C-B, 2C-C, 2C-D, 2C-E, 2C-P, 2C-T2, and 2C-T7) of NPS were analyzed via 60 MHz ¹ H benchtop NMR spectroscopy and their molecular structural relations are discussed with respect to the observed proton NMR spectra.

Comparative study of the analysis of seized samples by GC-MS, 1H NMR and FT-IR spectroscopy within a Night-Time Economy (NTE) setting

Rapid analysis of surrendered or seized drug samples provides important intelligence for health (e.g. treatment or harm reduction), and custodial services. Herein, three in-situ techniques, GC-MS, ¹H NMR and FT-IR spectroscopy, with searchable libraries, are used to analyse 318 samples qualitatively, using technique specific library-based searches, obtained over the period 24th - 29th August 2019. 259 samples were identified as consisting of a single component, of which cocaine was the most prevalent (n = 158). Median match scores for all three techniques were ≥ 0.84 and showed agreement except for metformin (n = 1), oxandrolone (identified as vitamin K by IR (n = 4)), diazepam (identified as zolpidem by FT-IR (n = 2)) and 2-Br-4,5-DMPEA (n = 1), a structural isomer of 2C-B identified as a polymer of cellulose (cardboard) by FT-IR. 51 samples were found to consist of two or more components, of which 49 were adulterated cocaine samples (45 binary and 4 tertiary samples). GC-MS identified all components present in the 49 adulterated cocaine samples, whereas IR identified only cocaine in 88 % of cases (adulterant only = 12 %). The breakdown for ¹H NMR spectroscopy was all components identified (51 %), cocaine only (33 %), adulterant only (10 %), cocaine and one adulterant (tertiary mixtures only, 6 %).

Characterization of new psychoactive substances by integrating benchtop NMR to multi-technique databases

New psychoactive substances (NPS) have become a serious threat for public health due to their ability to be sold in the street or on internet. NPS are either derived from commercial drugs which are misused (recreational rather than medical use) or whose structure is slightly modified. To regulate NPS, it is essential to accurately characterize them, either to recognize molecules that were previously identified or to quickly elucidate the structure of unknown ones. Most approaches rely on the determination of the exact mass obtained by high‐resolution mass spectrometry requiring expensive equipment. This motivated us to develop a workflow in which the elucidation is assisted with databases and does not need the exact mass. This workflow combines 1D and 2D NMR measurements performed on a benchtop spectrometer with IR spectroscopy, for creating a multi‐technique database to characterize pure and mixed NPS. The experimental database was created with 57 entries mostly coming from seizures, mainly cathinones, cannabinoids, amphetamines, arylcyclohexylamines, and fentanyl. A blind validation of the workflow was carried out on a set of six unknown seizures. In the first three cases, AF, AB‐FUBINACA, and a mixture of 2C‐I and 2C‐E could be straightforwardly identified with the help of their reference spectra in the database. The two next samples were elucidated for the first time with the help of the database to reveal NEK and MPHP substances. Finally, a precise quantification of each characterized NPS was obtained in order to track NPS trafficking networks.

Identification of the polymer-bounded drugs on the fabric surface: A challenge to the forensic drug analysts

Drug trafficking through concealment has always been a method of choice for drug traffickers all around the world. This case shares a new trend in the smuggling of illicit drugs by applying a coating of drug and polymer mixture on fabric. A white fabric sample was submitted by a law enforcement agency to detect the presence of any explosive material on its surface. Later on it was also tested for illicit drugs. Stereomicroscope and Scanning Electron Microscope/Energy Dispersive X-ray Detector (SEM/EDX) were applied for microscopic examination. Acetone extract of the sample was analyzed for explosives by explosive detection kit, Gas Chromatography Mass Spectrometry (GCMS), and Fourier Transform Infrared Spectroscopy (FTIR). The routine method involving methanol as solvent was used to check heroin presence. Methanol extract of the sample was analyzed by Mecke test and GCMS. Stereomicroscope and SEM/EDX revealed the presence of some unusual coating on one side of fabric. No explosive material was detected; instead GCMS (method 1) confirmed the presence of heroin (mass fragments 268, 310, 327, and 369 m/z) and FTIR spectrum revealed presence of a polymeric material (dyneema). No drug was identified by GCMS (method 2). Method 2 was modified by replacing methanol with acetone and including an additional step of sonication for 30 min. Acetone extract showed green color with Mecke reagent and a strong signal of heroin on GCMS. This modified extraction method acted well to unbind the coated material from the fabric and to disentangle the drug from the polymer.

Recent Applications of Benchtop Nuclear Magnetic Resonance Spectroscopy

Benchtop nuclear magnetic resonance (NMR) spectroscopy uses small permanent magnets to generate magnetic fields and therefore offers the advantages of operational simplicity and reasonable cost, presenting a viable alternative to high-field NMR spectroscopy. In particular, the use of benchtop NMR spectroscopy for rapid in-field analysis, e.g., for quality control or forensic science purposes, has attracted considerable attention. As benchtop NMR spectrometers are sufficiently compact to be operated in a fume hood, they can be efficiently used for real-time reaction and process monitoring. This review introduces the recent applications of benchtop NMR spectroscopy in diverse fields, including food science, pharmaceuticals, process and reaction monitoring, metabolomics, and polymer materials.

Low-field benchtop NMR spectroscopy: status and prospects in natural product analysis†

INTRODUCTION

Since a couple of years, low-field (LF) nuclear magnetic resonance (NMR) spectrometers (40-100 MHz) have re-entered the market. They are used for various purposes including analyses of natural products. Similar to high-field instruments (300-1200 MHz), modern LF instruments can measure multiple nuclei and record two-dimensional (2D) NMR spectra.

OBJECTIVE

To review the commercial availability as well as applications, advantages, limitations, and prospects of LF-NMR spectrometers for the purpose of natural products analysis.

METHOD

Commercial LF instruments were compared. A literature search was performed for articles using and discussing modern LF-NMR. Next, the articles relevant to natural products were read and summarised.

RESULTS

Seventy articles were reviewed. Most appeared in 2018 and 2019. Low costs and ease of operation are most often mentioned as reasons for using LF-NMR.

CONCLUSION

As the spectral resolution of LF instruments is limited, they are not used for structure elucidation of new natural products but rather applied for quality control (QC), forensics, food and health research, process control and teaching. Chemometric data handling is valuable. LF-NMR is a rapidly developing niche and new instruments keep being introduced.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Rapid Identification of Novel Psychoactive and Other Controlled Substances Using Low-Field 1H NMR Spectroscopy

An automated approach to the collection of ¹H NMR (nuclear magnetic resonance) spectra using a benchtop NMR spectrometer and the subsequent analysis, processing, and elucidation of components present in seized drug samples are reported. An algorithm is developed to compare spectral data to a reference library of over 300 ¹H NMR spectra, ranking matches by a correlation-based score. A threshold for identification was set at 0.838, below which identification of the component present was deemed unreliable. Using this system, 432 samples were surveyed and validated against contemporaneously acquired GC-MS (gas chromatography-mass spectrometry) data. Following removal of samples which possessed no peaks in the GC-MS trace or in both the ¹H NMR spectrum and GC-MS trace, the remaining 416 samples matched in 93% of cases. Thirteen of these samples were binary mixtures. A partial match (one component not identified) was obtained for 6% of samples surveyed whilst only 1% of samples did not match at all.