The utility of silica hydride-based stationary phases for dual-mode ultra high performance liquid chromatography separation of synthetic cathinone positional isomers

Utility of "flip-flop" chromatography employing silica hydride stationary phases with simultaneous photodiode array ultraviolet and single quadrupole mass detection for the analysis of seized drugs

For confirmation and/or screening purposes, rapid, selective, and precise chromatographic methods are required. In this vein, the utility of SiH columns (C18, UDC Cholesterol, and Diamond Hydride) with photodiode array UV absorption and single quadrupole MS detection for multi-modal separation of representative drugs from different drug classes on a single column using the same solvent reservoirs was investigated. For a conventional two column approach employing a combination of conventional C18 and silica columns operating in both the reversed phase chromatographic and hydrophilic interaction chromatographic modes, gradient analysis is required for the first column and there is a lack of retention on the second column for non-amine analytes. In comparison, all analytes are retained for two relatively rapid (< 10 min), precise (% RSD <0.4%), and non-correlated isocratic separations (R2=0.2115) when using a UDC Cholesterol column.

Detection, discrimination and quantification of amphetamine, cathinone and nor-ephedrine regioisomers using benchtop 1 H and 19 F nuclear magnetic resonance spectroscopy

Amphetamine and cathinone derivatives are abused recreationally due to the sense of euphoria they provide to the user. Methodologies for the rapid detection of the drug derivative present in a seized sample, or an indication of the drug class, are beneficial to law enforcement and healthcare providers. Identifying the drug class is prudent because derivatisation of these drugs, to produce regioisomers, for example, occurs frequently to circumvent global and local drug laws. Thus, newly encountered derivatives might not be present in a spectral library. Employment of benchtop nuclear magnetic resonance (NMR) could be used to provide rapid analysis of seized samples as well as identifying the class of drug present. Discrimination of individual amphetamine-, methcathinone-, N-ethylcathinone and nor-ephedrine-derived fluorinated and methylated regioisomers is achieved herein using qualitative automated ¹ H NMR analysis and compared to gas chromatography-mass spectrometry (GC-MS) data. Two seized drug samples, SS1 and SS2, were identified to contain 4-fluoroamphetamine by ¹ H NMR (match score median = 0.9933) and GC-MS (RR_t  = 5.42-5.43 min). The amount of 4-fluoroamphetamine present was 42.8%-43.4% w/w and 48.7%-49.2% w/w for SS1 and SS2, respectively, from quantitative ¹⁹ F NMR analysis, which is in agreement with the amount determined by GC-MS (39.9%-41.4% w/w and 49.0%-49.3% w/w). The total time for the qualitative ¹ H NMR and quantitative ¹⁹ F NMR analysis is ~10 min. This contrasts to ~40 min for the GC-MS method. The NMR method also benefits from minimal sample preparation. Thus, benchtop NMR affords rapid, and discriminatory, analysis of the drug present in a seized sample.

A Quantitative LC–MS/MS Method for the Detection of 16 Synthetic Cathinones and 10 Metabolites and Its Application to Suspicious Clinical and Forensic Urine Samples

Background: Synthetic cathinones currently represent one of the most predominant (sub)-classes of new psychoactive substance (NPS) in illicit drug markets. Despite the increased concerns caused by the constant introduction of new analogues, these drugs are not commonly assayed in routine drug testing procedures and may not be detected in standard screening procedures. This study presents a validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the detection and quantification of 16 synthetic cathinones and 10 metabolites in human urine. Methods: The method was validated for all analytes using published guidelines. The evaluated parameters achieved acceptable values according to the set criteria. Potential abuse of synthetic cathinones was investigated in suspicious urine samples from Saudi Arabia originating from workplace drug testing, pre-employment and Accident & Emergency (A&E). Such samples generated a presumptive positive immunoassay for amphetamine; however, they yielded a negative LC–MS/MS confirmation for this analyte, following the recommended cutoff values of Substance of Abuse and Mental Health Services Administration (SAMHSA) guidelines. Results: 5.8% of the analyzed samples were found to contain at least one target analyte, namely mephedrone and N-ethylpentylone, as well as their dihydro-metabolites. The results also revealed polydrug use with the synthetic cathinones being present together with other classical stimulant drugs. Conclusions: This is the first report of NPS use in Saudi Arabia with respect to designer stimulant drugs. Confirmatory urine analyses for suspicious stimulant use should extend beyond classical stimulants to cover a broad range of NPSs and their metabolites in order to report any otherwise potentially undetected/new analyte.

Simultaneous Determination of 16 Kinds of Synthetic Cathinones in Human Urine Using a Magnetic Nanoparticle Solid-Phase Extraction Combined with Gas Chromatography-Mass Spectrometry

A specific and sensitive approach using magnetic nanoparticle solid-phase extraction combined with gas chromatography-mass spectrometry (GC-MS) was carried out and applied in the simultaneous determination of 16 kinds of synthetic cathinones in human urine. The functionalized extraction material (Fe3O4/NH2-MWCNTs) was synthesized and factors affecting the extraction efficiency were all tested. Under the optimized conditions of magnetic nanoparticle solid-phase extraction, the determination of synthetic cathinones in human urine was carried out with GC-MS. Good linear relationships of 16 kinds of synthetic cathinones were obtained in the range of 0.005–5.00 μg/mL with the correlation coefficients (r) ranging from 0.9901 to 0.9979, the limits of detection were in the range between 0.005 and 0.01 μg/mL, and the limits of quantitation were between 0.01 and 0.02 μg/mL. Furthermore, the average intra-day precisions were below 8.90%, the average inter-day precisions were less than 9.52%, and the average recoveries were between 87.03% and 99.13%, respectively. The results show the advantages of the approach in the determination of trace synthetic cathinones in complex matrixes, such as environmentally friendly, fast detection, high efficiency and sensitivity. The practical application indicated that this method could provide scientific basis for the determination of drugs of abuse in forensic laboratories.

Silica Hydride: A Separation Material Every Analyst Should Know About

This review describes the development, special features and applications of silica hydride-based stationary phases for HPLC. The unique surface of this material is in contrast to ordinary, standard silica, which is the material most frequently used in modern HPLC stationary phases. The standard silica surface contains mainly silanol (Si-OH) groups, while the silica hydride surface is instead composed of silicon-hydrogen groups, which is much more stable, less reactive and delivers different chromatographic and chemical characteristics. Other aspects of this material are described for each of the different bonded moieties available commercially. Some applications for each of these column types are also presented as well as a generic model for method development on silica hydride-based stationary phases.

Recent forensic applications of enhanced chromatographic separation methods

This study reviews the recent applications of enhanced separation methods employed in forensic analysis utilizing gas chromatography, liquid chromatography, and supercritical fluid chromatography published between 2015 to 2020, except papers previously covered in relevant review articles. Applications of enhanced chromatographic separation methods to arson investigations, environmental forensics, sexual assault investigations, drug analysis, and toxicology are discussed. Future directions for enhanced chromatographic separation methods in forensic science are also explored.

The separation and identification of synthetic cathinones by portable low microflow liquid chromatography with dual capillary columns in series and dual wavelength ultraviolet detection

This study ascertained the viability of a portable liquid chromatograph, operating at low microliter per minute flow, for the analysis of seized drugs at remote sites as well as in laboratory settings. Synthetic cathinones were screened using dual capillary columns in series, C8 and biphenyl, with on-column ultraviolet detection at 255 and 275 nm. The relative retention times of the two columns in series and their peak area absorbance ratio were used to determine if the 16 synthetic cathinones investigated could be uniquely identified in these conditions. Based on these parameters all of the analytes could be distinguished. Representative mixtures of synthetic cathinones were used to determine the repeatability, linearity, and limits of detection of the method. This cost effective and green instrumentation has the potential to satisfy minimum international guidelines for the analysis of seized drugs.