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Liliedahl RE, Hutzell E, Haley M, Predecki DP, Davidson JT. The differentiation of N-butyl pentylone isomers using GC-EI-MS and NMR. Forensic Sci Int 2023; 351:111815. [PMID: 37713773 DOI: 10.1016/j.forsciint.2023.111815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 08/21/2023] [Accepted: 08/29/2023] [Indexed: 09/17/2023]
Abstract
Forensic laboratories are faced with an ever-expanding seized drug landscape including the increasing prevalence of novel psychoactive substances (NPS), such as synthetic cathinones, that have varying potencies and scheduling. This study demonstrates a combined gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) and nuclear magnetic resonance (NMR) spectroscopy approach for the differentiation of N-butyl pentylone isomers based on distinct retention times, characteristic EI mass spectra, and NMR characterization. Retention time reproducibility was assessed from 60 replicate measurements for each isomer over the course of a month. In addition, the effect of the mass spectrometer tune and the stability of an identified characteristic ion ratio using spectral data from ± 1 scan on either side of the peak apex were also statistically assessed using Welch's ANOVA testing. The presence of diastereomers for N-sec-butyl pentylone was identified using the developed GC-EI-MS method, which was confirmed using one-dimensional and two-dimensional NMR spectroscopy. The retention time reproducibility of the chromatographic method was ± 0.076% or less over the course of a month. An identified characteristic ion ratio between the abundance of the fragment ion at m/z 128 and the fragment ion at m/z 72 enabled the differentiation of the four N-butyl pentylone isomers, even when accounting for the effect of the mass spectrometer tune and mass spectral scans used to calculate the characteristic ion ratio. The 95% confidence interval mean abundance ratio of the fragment ions at m/z 128 and m/z 72 was 17.14 ± 0.14 for N-butyl pentylone, 6.44 ± 0.05 for N-isobutyl pentylone, 3.38 ± 0.02 for N-sec-butyl pentylone, and 0.75 ± 0.01 for N-tert-butyl pentylone. These results highlight the capabilities of a combined GC-EI-MS and NMR approach for the differentiation and characterization of synthetic cathinone isomers.
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Affiliation(s)
- Ruby E Liliedahl
- Department of Forensic Science, Sam Houston State University, Huntsville, TX, USA
| | - Elise Hutzell
- Department of Chemistry, Shippensburg University, Shippensburg, PA, USA
| | - Madison Haley
- Department of Chemistry, Shippensburg University, Shippensburg, PA, USA
| | - Daniel P Predecki
- Department of Chemistry, Shippensburg University, Shippensburg, PA, USA.
| | - J Tyler Davidson
- Department of Forensic Science, Sam Houston State University, Huntsville, TX, USA.
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2
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Majeed HA, Bos TS, Voeten RLC, Kranenburg RF, van Asten AC, Somsen GW, Kohler I. Trapped ion mobility mass spectrometry of new psychoactive substances: Isomer-specific identification of ring-substituted cathinones. Anal Chim Acta 2023; 1264:341276. [PMID: 37230720 DOI: 10.1016/j.aca.2023.341276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/18/2023] [Accepted: 04/23/2023] [Indexed: 05/27/2023]
Abstract
New psychoactive substances (NPS) are synthetic derivatives of illicit drugs designed to mimic their psychoactive effects. NPS are typically not controlled under drug acts or their legal status depends on their molecular structure. Discriminating isomeric forms of NPS is therefore crucial for forensic laboratories. In this study, a trapped ion mobility spectrometry time-of-flight mass spectrometry (TIMS-TOFMS) approach was developed for the identification of ring-positional isomers of synthetic cathinones, a class of compounds representing two-third of all NPS seized in Europe in 2020. The optimized workflow features narrow ion-trapping regions, mobility calibration by internal reference, and a dedicated data-analysis tool, allowing for accurate relative ion-mobility assessment and high-confidence isomer identification. Ortho-, meta- and para-isomers of methylmethcathinone (MMC) and bicyclic ring isomers of methylone were assigned based on their specific ion mobilities within 5 min, including sample preparation and data analysis. The resolution of two distinct protomers per cathinone isomer added to the confidence in identification. The developed approach was successfully applied to the unambiguous assignment of MMC isomers in confiscated street samples. These findings demonstrate the potential of TIMS-TOFMS for forensic case work requiring fast and highly-confident assignment cathinone-drug isomers in confiscated samples.
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Affiliation(s)
- Hany A Majeed
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands; Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands
| | - Tijmen S Bos
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands; Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands
| | - Robert L C Voeten
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands; Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands
| | - Ruben F Kranenburg
- Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands; Forensic Laboratory, Unit Amsterdam, Dutch National Police, Kabelweg 25, 1014 BA, Amsterdam, the Netherlands; Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD, Amsterdam, the Netherlands
| | - Arian C van Asten
- Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands; Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD, Amsterdam, the Netherlands; Co van Ledden Hulsebosch Center (CLHC), Amsterdam Center for Forensic Science and Medicine, P.O. Box 94157, 1090 GD, Amsterdam, the Netherlands
| | - Govert W Somsen
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands; Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands
| | - Isabelle Kohler
- Division of Bioanalytical Chemistry, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands; Centre for Analytical Sciences Amsterdam (CASA), 1098 XH, Amsterdam, the Netherlands; Co van Ledden Hulsebosch Center (CLHC), Amsterdam Center for Forensic Science and Medicine, P.O. Box 94157, 1090 GD, Amsterdam, the Netherlands.
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3
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Kranenburg RF, Ramaker HJ, van Asten AC. Portable near infrared spectroscopy for the isomeric differentiation of new psychoactive substances. Forensic Sci Int 2022; 341:111467. [PMID: 36154979 DOI: 10.1016/j.forsciint.2022.111467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/01/2022] [Accepted: 09/15/2022] [Indexed: 11/04/2022]
Abstract
Rapid and efficient identification of the precise isomeric form of new psychoactive substances (NPS) by forensic casework laboratories is a relevant challenge in the forensic field. Differences in legal status occur for ring-isomeric species of the same class, thus leading to different penalties and judicial control. Portable systems such as near-infrared (NIR) spectroscopy recently emerged as suitable techniques for the on-scene identification of common drugs of abuse such as cocaine, MDMA and amphetamine. This way, the overall forensic process becomes more efficient as relevant information on substance identity becomes available directly at the scene of crime. Currently, no NIR-based applications exist for the rapid, on-scene detection of NPS isomers. Herein, we present the differentiation of cathinone and phenethylamine-type NPS analogues based on their NIR spectrum recorded in 2 seconds on a portable 1350 - 2600 nm spectrometer. A prior developed data analysis model was found suitable for the identification of the methylmethcathinone (MMC) isomers 2-MMC, 3-MMC and 4-MMC. In 51 mixtures and 22 seized casework samples, the correct isomeric form was detected in all cases except for a few mixtures with an active ingredient content of 10 wt%. These results show the feasibility of on-site NPS detection as presumptive test performed directly at the scene of crime with a small size NIR-spectrometer. Additionally, in the illicit drug analysis laboratory the combination of NIR and GC-MS analysis might be suitable for robust identification of NPS isomers and analogues.
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Affiliation(s)
- Ruben F Kranenburg
- Dutch National Police, Unit Amsterdam, Forensic Laboratory, Kabelweg 25, Amsterdam 1014 BA, the Netherlands; Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Postbus 94157, Amsterdam 1090 GD, the Netherlands.
| | - Henk-Jan Ramaker
- TIPb, Koningin Wilhelminaplein 30, Amsterdam 1062 KR, the Netherlands
| | - Arian C van Asten
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Postbus 94157, Amsterdam 1090 GD, the Netherlands; Co van Ledden Hulsebosch Center (CLHC), Amsterdam Center for Forensic Science and Medicine, Postbus 94157, Amsterdam 1090 GD, the Netherlands
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4
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Sharp J, Do D, Tyler Davidson J. Assessment of the similarity between in-source collision-induced dissociation (IS-CID) fragment ion spectra and tandem mass spectrometry (MS/MS) product ion spectra for seized drug identifications. Forensic Chem 2022. [DOI: 10.1016/j.forc.2022.100441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Kranenburg RF, Ou F, Sevo P, Petruzzella M, de Ridder R, van Klinken A, Hakkel KD, van Elst DM, van Veldhoven R, Pagliano F, van Asten AC, Fiore A. On-site illicit-drug detection with an integrated near-infrared spectral sensor: A proof of concept. Talanta 2022; 245:123441. [DOI: 10.1016/j.talanta.2022.123441] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/24/2022] [Accepted: 04/01/2022] [Indexed: 12/15/2022]
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6
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Aslani S, Armstrong DW. High Information Spectroscopic Detection Techniques for Gas Chromatography. J Chromatogr A 2022; 1676:463255. [DOI: 10.1016/j.chroma.2022.463255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/10/2022] [Accepted: 06/14/2022] [Indexed: 01/14/2023]
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Reavis M, Goodpaster J. Quantitative analysis of smokeless powder particles in post‐blast debris via gas chromatography/vacuum ultraviolet spectroscopy (
GC
/
VUV
). J Forensic Sci 2022; 67:1431-1440. [PMID: 35368092 PMCID: PMC9322668 DOI: 10.1111/1556-4029.15037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/05/2022] [Accepted: 03/21/2022] [Indexed: 11/29/2022]
Abstract
Forensic analysis of smokeless powder particles recovered from the debris of an improvised explosive device can provide information about the type of smokeless powder used and can aid investigation efforts. In this study, quantitative methods were used to yield information about the difference in the chemical composition of the particles pre‐ and post‐blast. The technique, gas chromatography/vacuum ultraviolet spectroscopy (GC/VUV), was able to quantify nitroglycerin, 2,4‐dinitrotoluene, diphenylamine, ethyl centralite, and di‐n‐butyl phthalate in pre‐ and post‐blast smokeless powder particles using heptadecane as an internal standard. Post‐blast debris was obtained via controlled explosions with assistance from the Indiana State Police Bomb Squad. Two galvanized steel and two polyvinyl chloride pipe bombs were assembled. Two devices contained single‐base smokeless powder and two contained double‐base smokeless powder. 2,4‐dinitrotoluene and diphenylamine were successfully quantified in the single‐base smokeless powder post‐blast debris while nitroglycerin, diphenylamine, and ethyl centralite were successfully quantified in the double‐base smokeless powder post‐blast debris. Compounds were detected at concentrations as low as 9 μg of 2,4‐dinitrotoluene per mg, <3 μg of diphenylamine per mg, 131 μg of nitroglycerin per mg, and <3 μg of ethyl centralite per mg. Concentration changes between pre‐ and post‐blast smokeless powder particles were determined as well as microscopic differences between pre‐ and post‐blast debris for both smokeless powders in all devices. To our knowledge, this is the first use of GC/VUV for the quantification of explosives.
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Affiliation(s)
- Madison Reavis
- Forensic and Investigative Sciences Department Indiana University—Purdue University Indianapolis Indianapolis Indiana USA
| | - John Goodpaster
- Forensic and Investigative Sciences Department Indiana University—Purdue University Indianapolis Indianapolis Indiana USA
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8
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Bonetti JL, Samanipour S, van Asten AC. Utilization of Machine Learning for the Differentiation of Positional NPS Isomers with Direct Analysis in Real Time Mass Spectrometry. Anal Chem 2022; 94:5029-5040. [PMID: 35297608 PMCID: PMC8968871 DOI: 10.1021/acs.analchem.1c04985] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
The differentiation
of positional isomers is a well established
analytical challenge for forensic laboratories. As more novel psychoactive
substances (NPSs) are introduced to the illicit drug market, robust
yet efficient methods of isomer identification are needed. Although
current literature suggests that Direct Analysis in Real Time–Time-of-Flight
mass spectrometry (DART-ToF) with in-source collision induced dissociation
(is-CID) can be used to differentiate positional isomers, it is currently
unclear whether this capability extends to positional isomers whose
only structural difference is the precise location of a single substitution
on an aromatic ring. The aim of this work was to determine whether
chemometric analysis of DART-ToF data could offer forensic laboratories
an alternative rapid and robust method of differentiating NPS positional
ring isomers. To test the feasibility of this technique, three positional
isomer sets (fluoroamphetamine, fluoromethamphetamine, and methylmethcathinone)
were analyzed. Using a linear rail for consistent sample introduction,
the three isomers of each type were analyzed 96 times over an eight-week
timespan. The classification methods investigated included a univariate
approach, the Welch t test at each included ion;
a multivariate approach, linear discriminant analysis; and a machine
learning approach, the Random Forest classifier. For each method,
multiple validation techniques were used including restricting the
classifier to data that was only generated on one day. Of these classification
methods, the Random Forest algorithm was ultimately the most accurate
and robust, consistently achieving out-of-bag error rates below 5%.
At an inconclusive rate of approximately 5%, a success rate of 100%
was obtained for isomer identification when applied to a randomly
selected test set. The model was further tested with data acquired
as a part of a different batch. The highest classification success
rate was 93.9%, and error rates under 5% were consistently achieved.
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Affiliation(s)
- Jennifer L Bonetti
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands.,Virginia Department of Forensic Science, Norfolk, Virginia 23606, United States
| | - Saer Samanipour
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands
| | - Arian C van Asten
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands.,Co van Ledden Hulsebosch Center (CLHC), Amsterdam Center for Forensic Science and Medicine, 1098 XH Amsterdam, The Netherlands
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9
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Madunil SL, Imasaka T, Imasaka T. Comprehensive Analysis of Analogues of Amine-Related Psychoactive Substances Using Femtosecond Laser Ionization Mass Spectrometry. J Am Soc Mass Spectrom 2022; 33:90-99. [PMID: 34846136 DOI: 10.1021/jasms.1c00282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Amine-related psychoactive molecules contain N-Cα and Cα-Cβ bonds, which easily dissociate to form various fragment ions in electron ionization mass spectrometry (EIMS). Therefore, observing a molecular ion and then determining the molecular weight of the analyte is difficult. In this study, we examined phenethylamine, 3,4-methylenedioxyphenethylamine, tryptamine, N-methylephedrine, and nicotine as well as analogues of amine-related psychoactive substances using EIMS and femtosecond laser ionization mass spectrometry (fs-LIMS) combined with gas chromatography for comprehensive analysis. A molecular ion was clearly observed in fs-LIMS for all of these compounds, which was in contrast to EIMS providing fragment ions dominantly (no molecular ion was observed for N-methylephedrine). This favorable result was obtained by adjusting the laser wavelength to the optimal value for two-photon ionization to minimize the excess energy remaining in the molecular ion. It therefore appears that fs-LIMS is superior to EIMS in terms of observing a molecular ion and would be potentially useful for identifying a variety of amine-related psychoactive substances, some of which are illegal and are of interest in the field of forensic science.
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Affiliation(s)
- Siddihalu Lakshitha Madunil
- Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540:744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Totaro Imasaka
- Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- Hikari Giken, Co., 2-10-30, Sakurazaka, Chuou-ku, Fukuoka 810-0024, Japan
| | - Tomoko Imasaka
- Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540:744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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10
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Meng L, Ye S, Wu Y, You L. Determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction and capillary electrophoresis with PDA detection. Forensic Sci Res 2021; 7:265-271. [PMID: 35784428 PMCID: PMC9245984 DOI: 10.1080/20961790.2021.1986771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
A new method was developed for pre-concentration and determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction (DLLME) and capillary electrophoresis (CE) with photodiode array detection. The method was based on the formation of tiny droplets of an organic extractant in the prepared sample solution using water-immiscible organic solvent (chloroform) dissolved in water-miscible organic dispersive solvent (isopropyl alcohol). The organic phase, which extracted eight drugs of abuse from the prepared urine solution, was separated by centrifugation. The sedimented phase was transferred into a small volume CE auto-sampler vial with 10 µL of 1% HCl methanol solution and evaporated to dryness. The residue was reconstituted in lidocaine hydrochloride (internal standard) aqueous solution and introduced by electrokinetic injection into CE. Under the optimum conditions, acceptable linear relationship was observed in the range of 3.0–500 ng/mL with the correlation coefficient (r) of 0.9982–0.9994 for spiked urine samples. The limit of detection (LOD) (S/N = 3) was estimated to be 1.0 ng/mL. A recovery of 75.7%–90.6% was obtained for spiked samples. The mean relative error (MRE) was within ±7.0% and the relative standard deviation (RSD) was less than 6.9%. The proposed DLLME-CE procedure offers an alternative analytical approach for the sensitive detection of drugs of abuse in real urine samples.Key points The dispersive liquid-liquid microextraction (DLLME) was involved for the determination of drugs in urine with capillary electrophoresis with photodiode array detection (CE-PDA). Good linearity, sensitivity, recovery and precision were achieved. The proposed method was eco-friendly with microliter scale solvent consumption.
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Affiliation(s)
- Liang Meng
- Department of Forensic Science, Fujian Police College, Fuzhou, China
| | - Shuhai Ye
- Institute of Forensic Science, Fujian Provincial Public Security Department, Fuzhou, China
| | - Yilin Wu
- Department of Forensic Science, Fujian Police College, Fuzhou, China
| | - Linda You
- Department of Forensic Science, Fujian Police College, Fuzhou, China
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12
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Kranenburg RF, Stuyver LI, de Ridder R, van Beek A, Colmsee E, van Asten AC. Deliberate evasion of narcotic legislation: Trends visualized in commercial mixtures of new psychoactive substances analyzed by GC-solid deposition-FTIR. Forensic Chem 2021. [DOI: 10.1016/j.forc.2021.100346] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Feeney W, Moorthy AS, Sisco E. Spectral trends in GC-EI-MS data obtained from the SWGDRUG mass spectral library and literature: A resource for the identification of unknown compounds. Forensic Chem 2020; 31:10.1016/j.forc.2022.100459. [PMID: 36578315 PMCID: PMC9793444 DOI: 10.1016/j.forc.2022.100459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Rapid identification of new or emerging psychoactive substances remains a critical challenge in forensic drug chemistry laboratories. Current analytical protocols are well-designed for confirmation of known substances yet struggle when new compounds are encountered. Many laboratories initially attempt to classify new compounds using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS). Though there is a large body of research focused on the analysis of illicit substances with GC-EI-MS, there is little high-level discussion of mass spectral trends for different classes of drugs. This manuscript compiles literature information and performs simple exploratory analyses on evaluated GC-EI-MS data to investigate mass spectral trends for illicit substance classes. Additionally, this work offers other important aspects: brief discussions of how each class of drugs is used; illustrations of EI mass spectra with proposed structures of commonly observed ions; and summaries of mass spectral trends that can help an analyst classify new illicit compounds.
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Affiliation(s)
- William Feeney
- Corresponding author at: Surface and Trace Chemical Analysis Group, Material Measurement Laboratory, 100 Bureau Drive, Gaithersburg, MD 20899, USA. (W. Feeney)
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