![91暗网 Logo](/global/images/shsu.svg")
Research Lab: Davidson
Specific research endeavors include:
- Differentiation of hemp and marijuana
- Multivariate analysis for the classification of novel synthetic drugs
- Forensic applications of ambient ionization mass spectrometry (AI-MS)
- Exploration of alternative toxicological matrices
- Structural elucidation with tandem mass spectrometry (MS/MS) and high-resolution mass spectrometry (HRMS)
- Fundamental studies on the application of in-source CID to forensic science samples
- Pre-and post-blast explosives detection
- Field-portable instrumentation
Research Updates
-
Fall 2024 Davidson research group photo
October 2024
From left to right, Christany Liggins, Fiza Tajdin, Emma Hardwick, Dr. Davidson, Alleigh Couch, and Keshonna Towns.
-
Alleigh鈥檚 manuscript is published in a special issue on analytical developments for the quality and safety control of cannabis products in Talanta Open
October 2024
This manuscript describes the first application of Ag-phosphine ion complexation and a 1% semi-quantitative decision-point assay for identifying marijuana using direct mass spectrometry analysis. The ability to differentiate isomeric cannabinoids based on the formation of unique MS/MS product ions due to differences in the binding affinity between the Ag-phosphine complex and each cannabinoid shows great potential as an alternative to existing cannabis screening methods. The paper is available at DOI:
-
Emma鈥檚 manuscript on the structural characterization of nitazene analogs using electron ionization-mass spectrometry is published in Forensic Chemistry
September 2024
This manuscript provides the first comprehensive structural characterization of nitazene analogs using electron ionization-mass spectrometry (EI-MS). Nitazene analogs are highly potent novel synthetic opioids that have emerged in the wake of increased legislation in China and the United States to crack down on fentanyl and fentanyl analogs that have fueled the ongoing opioid epidemic. This study characterizes the fragmentation patterns and identifies characteristic EI fragment ions for 20 representative nitazene analogs to aid the seized drug community in identifying novel nitazene analogs. The paper is available at DOI:
-
The Davidson Group investigates the application of EAD for the identification of synthetic cathinone isomers
July 2024
The Davidson Group collaborated with Dr. Isabelle Kohler and her team at the Vrije Universiteit Amsterdam to investigate the application of electron-activated dissociation (EAD) mass spectrometry for the identification of synthetic cathinone isomers in seized drug casework samples. The collaboration also included Dr. Patrick Buzzini of 91暗网 for the development of Random Forest models for synthetic cathinone isomer classification based on the derived EAD mass spectra. The manuscript is available at DOI:
-
Dr. Davidson presents as part of the Opioid and Emerging Drugs AAFS Webinar Series
June 2024
Dr. Davidson presented recent group research involving Advances in Ambient Ionization Mass Spectrometry for Synthetic Opioid Analysis as part of the Opioids and Emerging Drugs AAFS Webinar Series.
-
Alleigh鈥檚 manuscript on the differentiation of 鈭�9-THC and CBD Using Silver-Ligand Ion Complexation is published in the Journal of the American Society for Mass Spectrometry
June 2024
This manuscript describes a novel approach to differentiate 鈭�9-THC and CBD using Ag-ligand ion complexation and electrospray ionization tandem mass spectrometry (ESI-MS/MS). Differences between the binding affinities of 鈭�9-THC and CBD for [Ag(PPh3)(OTf)]2 lead to the formation of unique product ions upon collision-induced dissociation, enabling the differentiation of these two phytocannabinoid isomers. When applied to authentic cannabis extracts with known 鈭�9-THC and CBD compositions, the developed direct mass spectrometry approach resulted in a 95% correct classification rate for the differentiation of 鈭�9-THC-rich and CBD-rich cannabis. The paper is available at DOI:
-
Alleigh Couch presents her research at the ASMS 72nd annual conference in Anaheim, CA
June 2024
Congratulations to Alleigh Couch for her poster presentation at the American Society for Mass Spectrometry (ASMS) 72nd annual conference in Anaheim, CA. The poster presentation covers her ongoing work with the development of in-field detection techniques for seized drug materials. The title of her poster is 鈥淚dentification of Isobaric Methyl-Substituted Fentanyl Analogs Using a Transportable Linear Ion Trap Mass Spectrometer.鈥�
-
Emma Hardwick passes her doctoral portfolio and qualifying examination
May 2024
Emma Hardwick successfully defended her doctoral portfolio and passed her qualifying examination on May 14th, 2024. Her dissertation proposal was titled 鈥淚dentification of Novel Nitazene Analogs Using Mass Spectrometry for Seized Drug Analysis.鈥�
-
Christina Chang and Claire Phelps graduate with their Master of Science in Forensic Science
May 2024
Christina Chang and Claire Phelps graduated on May 12th, 2024 with their Master of Science in Forensic Science. Christina鈥檚 research focused on the assessment of portable Raman spectroscopy and mass spectrometry instrumentation for the analysis of seized drugs. Claire鈥檚 research involved the development and validation of a combined selected ion monitoring (SIM)-scan method for the detection of nitazene analogs. Congratulations Christina and Claire!
-
The Davidson Group develops a novel seized drug screening method
March 2024
The Davidson Group publishes their recent work with the development of a novel seized drug screening method utilizing DART-MS and used weigh paper in Forensic Chemistry. The developed screening method provides the seized drug community with an alternative approach to rapidly screen seized drug evidence that utilizes used weigh paper already generated as part of the traditional seized drug analysis process. Implementation of the proposed method has the potential to enable higher throughput and increase laboratory efficiency. The paper is available at DOI:
-
Dr. Davidson chairs a workshop at the 2024 AAFS conference
February 2024
Dr. Davidson chaired a workshop at the 2024 American Academy of Forensic Sciences (AAFS) conference in Denver, CO. The workshop covered the recent work of the Forensic Laboratory Needs Technology Working Group (FLN-TWG) subcommittee on evolving approaches and technologies for seized drug analysis and was attended by 82 registrants. The white paper and corresponding technical notes developed by this subcommittee can be accessed can be accessed
-
Claire Phelps and Dr. Davidson co-present a poster at the AAFS 76th annual conference in Denver, CO
February 2024
Congratulations to Claire Phelps for her co-poster presentation at the American Academy of Forensic Sciences (AAFS) 76th annual conference in Denver, CO. The poster presentation covers recent work with the development of a novel seized drug screening method using DART-MS and used weigh paper. Her poster can be accessed here.
-
Christina Chang presents her research at the AAFS 76th annual conference in Denver, CO
February 2024
Congratulations to Christina Chang for her poster presentation at the American Academy of Forensic Sciences 76th annual conference in Denver, CO. The poster presentation covers Christina鈥檚 capstone research, which assesses a combined portable Raman spectroscopy and mass spectrometry approach for the analysis of seized drugs. Her poster can be accessed here.
-
Emma Hardwick presents her research at the AAFS 76th annual conference in Denver, CO
February 2024
Congratulations to Emma Hardwick for her poster presentation at the American Academy of Forensic Sciences 76th annual conference in Denver, CO. The poster presentation covers Emma鈥檚 capstone research focused on the structural characterization of nitazene analogs using electron ionization-mass spectrometry (EI-MS). Her poster can be accessed here.
-
Alleigh Couch presents her research at the AAFS 76th annual conference in Denver, CO
February 2024
Congratulations to Alleigh Couch for her poster presentation at the American Academy of Forensic Sciences 76th annual conference in Denver, CO. The poster presentation covers a portion of Alleigh鈥檚 dissertation research focused on the differentiation of hemp and marijuana using metal-ligand ion complexation. Her poster can be accessed here.
-
Dr. Davidson joins the editorial board of Forensic Chemistry
November 2023
Dr. Davidson has accepted an invitation to join the editorial board of Forensic Chemistry. Forensic Chemistry had a Cite score of 4.5 and an impact factor of 3.096 in 2022, among the highest impact factors for forensic science journals. Forensic Chemistry is also the preferred journal of the American Society of Crime Lab Directors (ASCLD).
-
The Davidson Group helps explore the capabilities of EAD for metabolite identification
November 2023
Dr. Davidson collaborated with Dr. Isabelle Kohler and her team at the Vrije Universiteit Amsterdam to explore the capabilities of electron-activated dissociation as a complementary fragmentation technique to collision-induced dissociation for synthetic cathinone positional isomer metabolite identification. The paper is available at DOI:
-
Alleigh Couch awarded a Lucas Research Grant from the Forensic Sciences Foundation
November 2023
Alleigh Couch received a to study the differentiation of CBD and 螖9-THC using copper ion complexation and electrospray ionization tandem mass spectrometry. This project is part of Alleigh鈥檚 dissertation research focused on the differentiation of hemp and marijuana using metal-ligand ion complexation.
-
Dr. Davidson presents a workshop at SWAFS on EI mass spectral interpretation
October 2023
Dr. Davidson presented a workshop at the Southwestern Association of Forensic Scientists (SWAFS) conference. The workshop was focused on electron ionization mass spectral interpretation and was attended by more than 80 registrants.
-
Alexis鈥� manuscript is published in Forensic Chemistry
September 2023
This manuscript investigates the effect of substitution location on fentanyl analog identification using GC-EI-MS and the NIST Simple Similarity Search and Hybrid Similarity Search algorithms. Careful examination of the EI mass spectra revealed several general trends about the influence of substitution location on the observed EI mass spectra that will assist with the identification of novel fentanyl analogs. The combination of unique fragmentation behavior and distinct retention times enabled the identification of the 11 methyl-substituted fentanyl analogs analyzed in this study. This manuscript is available via DOI:
-
The Davidson Group collaborates with Shippensburg University for the differentiation of synthetic cathinone isomers
September 2023
The Davidson group collaborated with Dr. Daniel Predecki and his team at Shippensburg University for the differentiation of N-butyl pentylone isomers using GC-EI-MS and NMR. The developed combined GC-EI-MS and NMR approach enabled the differentiation of N-butyl pentylone isomers based on distinct retention times, a characteristic ion ratio, and NMR characterization, including the identification of N-sec-butyl pentylone diastereomers. The paper is available via DOI:
-
Fall 2023 Davidson research group photo
September 2023
Claire Phelps (far left), Christina Chang (left center), Emma Hardwick (right center), Alleigh Couch (far right).
-
The Davidson Group collaborates with Vrije Universiteit Amsterdam on a drug metabolism study
July 2023
Dr. Davidson collaborated with Dr. Isabelle Kohler and her team at the Vrije Universiteit Amsterdam to assess sex-specific differences in the in vitro phase I metabolites of methylmethcathinone positional isomers. The paper titled In vitro metabolism of cathinone positional isomers: does sex matter? is available via DOI:
-
Alleigh Couch presents her research at the ASMS 71st annual conference in Houston, TX
June 2023
Congratulations to Alleigh Couch for her poster presentation at the American Society for Mass Spectrometry (ASMS) 71st annual conference in Houston, TX. The poster presentation covers the first phase of Alleigh鈥檚 dissertation titled 鈥淒ifferentiation of Hemp and Marijuana Using Ag-Ligand Ion Complexation and a Semi-Quantitative Decision-Point Assay.鈥�
-
Alexis Pollard graduates with her Master of Science in Forensic Science
May 2023
Alexis Pollard graduated on May 13th, 2023 with a Master of Science in Forensic Science. Her research focused understanding the effects of substitution location on fentanyl analog identification for methyl-substituted fentanyl analogs using GC-EI-MS. Congratulations Alexis!
-
Alleigh Couch passes her doctoral portfolio and qualifying examination
May 2023
Alleigh Couch successfully defended her doctoral portfolio and qualifying examination on May 5th, 2023. Her dissertation proposal was titled 鈥淒ifferentiation of Hemp and Marijuana Using Metal Ligand Ion Complexation.鈥�
-
Alexis Pollard and Alleigh Couch successfully defend their capstone research
April 2023
Alexis Pollard (left) and Alleigh Couch (right) successfully defended their capstone research projects on Wednesday, April 26th, 2023. Alexis鈥� research was titled 鈥淚nvestigating the Effects of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS鈥� and Alleigh鈥檚 research was titled 鈥淒ifferentiation of 螖9-THC and CBD Using Ag-Ligand Ion Complexation and ESI-MS/MS.鈥�
-
Alexis Pollard and Alleigh Couch present their research at the AAFS 75th Annual Conference
February 2023
Alexis Pollard (left) presented her capstone research titled 鈥淚nvestigating the Effect of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS鈥� on Wednesday, February 15th, 2023. Alleigh Couch (right) also presented her capstone research titled 鈥淒ifferentiation of 鈭�9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS)鈥� on Wednesday, February 15th, 2023.
-
Alexis Pollard presents her research at the AAFS 75th annual conference in Orlando, FL
February 2023
Congratulations to Alexis Pollard for her poster presentation at the American Academy of Forensic Sciences 75th annual conference in Orlando, FL. The poster presentation covers Alexis鈥� capstone research titled 鈥淚nvestigating the Effect of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS.鈥�
-
Alleigh Couch presents her research at the AAFS 75th annual conference in Orlando, FL
February 2023
Congratulations to Alleigh Couch for her poster presentation at the American Academy of Forensic Sciences 75th annual conference in Orlando, FL. The poster presentation covers Alleigh鈥檚 capstone research titled 鈥淒ifferentiation of 鈭�9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS).鈥�
-
Fall 2022 Davidson research group photo
November 2022
Emma Hardwick (front, left), Alexis Pollard (front, left center), Alleigh Couch (front, right center), Christina Chang (front, right), Ruby Liliedahl (back, right).
-
Alleigh Couch and Jared Sharp鈥檚 manuscript accepted for a special issue on Designer Drug Analysis in International Journal of Mass Spectrometry
October 2022
This manuscript provides the first assessment of the effectiveness of the NIST DART-MS Forensics Database and Data Interpretation Tool (DIT) for mixture interpretation when using other soft ionization sources or a different high-resolution mass spectrometer than the DART-AccuTOF instrumentation used for database creation. As the seized drug community continues to shift towards the use of in-source collision-induced dissociation (IS-CID) with single-stage mass spectrometers coupled with soft ionization sources, it is imperative to understand the effectiveness of the DIT for seized drug screening using instrumentation other than the DART-AccuTOF. This manuscript demonstrates the applicability of the freely available NIST DART-MS Forensics Database and DIT for the screening of seized drug mixtures using instrumentation other than the DART-AccuTOF. Available via DOI:
-
Jared Sharp and Daniel Do's manuscript accepted in Forensic Chemistry
August 2022
This manuscript investigates the use of spectral comparisons, breakdown curves, and Pearson product-moment correlations (PPMCs) to assess the similarity between IS-CID fragment ion spectra and MS/MS product ion spectra both visually and statistically. By providing seized drug analysts with an assessment of the spectral similarities and differences between IS-CID fragment ion spectra and MS/MS product ion spectra, as well as support for why these differences exist, this work helps inform analysts鈥� decisions regarding seized drug identifications based on the use of IS-CID fragment ion spectra. Available via DOI:
-
Daniel Do graduates with his Bachelor of Science in Forensic Chemistry
May 2022
Daniel Do graduated on May 14th, 2022 with a Bachelor of Science in Forensic Chemistry. Daniel spent the last nine months working in Dr. Davidson鈥檚 research group on a variety of research projects including the differentiation of unburned smokeless powders through visual and chemical analysis. Congratulations Daniel!
-
Jared Sharp graduates with his Master of Science in Forensic Science
May 2022
Jared Sharp graduated on May 13th, 2022 with a Master of Science in Forensic Science. Jared鈥檚 research focused on identifying similarities and differences between in-source collision-induced dissociation (IS-CID) fragment ion spectra and tandem mass spectrometry (MS/MS) product ion spectra for seized drug identifications. Congratulations Jared!
-
Daniel Do receives the best poster presentation awared at the 15th Annual 91暗网 Undergraduate Research Symposium
April 2022
Daniel Do is an undergraduate forensic chemistry major who worked with Dr. Davidson during his senior year to learn more about forensic science research. He was awarded the best poster presentation award at the 15th Annual 91暗网 Undergraduate Research Symposium for his poster presentation titled 鈥淒ifferentiating Unburned Smokeless Powders through Visual and Chemical Analysis鈥� on April 23rd, 2022.
-
Jared Sharp successfully presents his capstone research
April 2022
Jared Sharp presented his capstone research titled 鈥淚dentifying 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鈥� on April 22nd, 2022.
-
Jared Sharp and Ruby Liliedahl present their research at the AAFS 74th Annual Conference
February 2022
Jared Sharp presented his capstone research titled 鈥淚dentifying 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鈥� on Wednesday, February 23rd, 2022. Ruby Liliedahl presented her research from her internship this past summer with the Texas Department of Public Safety Houston Crime Laboratory during the toxicology poster session on Wednesday, February 23rd, 2022. Her research was titled 鈥淭he Effects of Storage Time, Adverse Storage Conditions, and Lab Exposure on Blood Alcohol Concentrations.鈥� Ruby was also awarded an FSF Student Affiliate Scholarship through AAFS, which provided her with complimentary meeting registration to attend the AAFS 74th Annual Conference from February 21-25, 2022.
-
Dr. Davidson presents in the 2022 Current Trends in Seized Drug Analysis Symposium
January 2022
Dr. Davidson presented a talk for the 2022 Current Trends in Seized Drug Analysis Symposium hosted through the Center for Forensic Science Research and Education (CFSRE). The presentation focused on the use of mass spectrometry fragmentation for novel psychoactive substance identification including highlighting ongoing research within the Davidson research group.
-
The Davidson research group grows!
September 2021
Jared Sharp (right), Alleigh Couch (center), and Daniel Do (left) join Dr. Davidson鈥檚 research group. Jared is working on his MS capstone research project focused on understanding the similarity between in-source collision-induced dissociation (IS-CID) fragment ion spectra and tandem mass spectrometry (MS/MS) product ion spectra used for seized drug identifications. Alleigh is a first year PhD student that will be exploring ambient ionization applications to forensic science and Daniel is an undergraduate chemistry student gaining exposure to forensic science research.
-
Ruby Liliedahl鈥檚 manuscript accepted in Forensic Chemistry
August 2021
This manuscript is from Ruby鈥檚 capstone research where she explored the application of multivariate analysis to the differentiation of synthetic cathinone isomers using GC-EI-MS. Ruby also explored multivariate ion selection methods and approaches to reduce the number of sample injections required for accurate multivariate classification. Available via DOI: .
-
Dr. Davidson presents an ASCLD FRC Lightning Talk on his previous fentanyl research
July 2021
Dr. Davidson presented a talk for the American Society of Crime Laboratory Directors (ASCLD) Forensic Research Committee (FRC) Lightning Talk series on Fentanyl Signature Research. The Lightning Talk series is available on .
-
Ruby Liliedahl passes her doctoral portfolio and qualifying examination
May 2021
Ruby Liliedahl passed her doctoral portfolio and qualifying examination on May 20th, 2021. Her dissertation proposal was titled 鈥淓xhaled Breath: Exploration of an Alternative Matrix.鈥�
-
Ruby Liliedahl successfully presents her capstone research
April 2021
Ruby Liliedahl presented her capstone research titled 鈥淒ifferentiation of Synthetic Cathinone Isomers Using GC-EI-MS and Multivariate Analysis鈥� on April 21st, 2021 to complete her capstone research project.
-
Ruby Liliedahl presents her research at the AAFS 73rd Annual Conference
February 2021
Ruby Liliedahl presented her capstone research titled 鈥淒ifferentiation of Synthetic Cathinone Isomers by GC-EI-MS and Multivariate Analysis鈥� on Thursday, February 18th, 2021 at the AAFS 73rd Annual Virtual Scientific Meeting.
-
Ruby Liliedahl receives a FSF Student Affiliate Scholarship through AAFS
January 2021
Ruby Liliedahl is a recipient of the Forensic Sciences Foundation (FSF) Student Scholarship Award through the American Academy of Forensic Sciences (AAFS). Ruby will receive complimentary registration to attend the AAFS 73rd Annual Virtual Scientific Meeting held February 15-19, 2021.
-
In-Source CID manuscript accepted in the Journal of Mass Spectrometry
November 2020
This work provides a comparison between in-source CID and beam-type CID spectra of emerging synthetic drugs on the same Q-TOF instrument to better understand the fragmentation differences between these two fragmentation techniques, and to contribute to the scientific foundations of in-source CID. Available via DOI: .
-
Dr. Davidson brings DART to 91暗网
October 2020
is a rapid and noncontact ambient ionization source that allows for the direct testing of solid, liquid, or gas samples without the need for extensive sample preparation or extraction. 91暗网 now joins a growing network of academic, industrial, and government laboratories using DART-MS. DART-MS is a branch of Dr. Davidson鈥檚 ambient ionization mass spectrometry (AI-MS) research agenda here at 91暗网.
-
Welcome to the Team - Ruby Liliedahl
September 2020
Ruby Liliedahl joins Dr. Davidson鈥檚 research group for her MS capstone project. Ruby is working on the differentiation of synthetic cathinone isomers using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) and multivariate analysis.
-
Welcome to the Team - Dr. Tyler Davidson
August 2020
Dr. Davidson joined the Department of Forensic Science at 91暗网 as an Assistant Professor.
-
21st Annual FSF Emerging Forensic Scientist Award
April 2020
J. Tyler Davidson was awarded the for his presentation titled, 鈥淥n the Fragmentation Behavior of Fentanyl and Its Analogs in Electrospray Ionization-Tandem Mass Spectrometry (ESI-MS/MS)鈥�.