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
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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’s 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.
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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’s capstone research focused on the structural characterization of nitazene analogs using electron ionization-mass spectrometry (EI-MS). Her poster can be accessed here.
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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’s dissertation research focused on the differentiation of hemp and marijuana using metal-ligand ion complexation. Her poster can be accessed here.
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Dr. Davidson joins the editorial board of Forensic Chemistry
November 2024
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).
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The Davidson Group helps explore the capabilities of EAD for metabolite identification
November 2024
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: 10.1016/j.aca.2023.341962.
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Alleigh Couch awarded a Lucas Research Grant from the Forensic Sciences Foundation
November 2024
Alleigh Couch received a Forensic Sciences Foundation Lucas Research Grant to study the differentiation of CBD and Δ9-THC using copper ion complexation and electrospray ionization tandem mass spectrometry. This project is part of Alleigh’s dissertation research focused on the differentiation of hemp and marijuana using metal-ligand ion complexation.
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Dr. Davidson presents a workshop at SWAFS on EI mass spectral interpretation
October 2024
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.
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Alexis’ 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: 10.1016/j.forc.2023.100534.
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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: 10.1016/j.forsciint.2023.111815.
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Fall 2023 Davidson research group photo
September 2023
Claire Phelps (far left), Christina Chang (left center), Emma Hardwick (right center), Alleigh Couch (far right).
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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: 10.1007/s00216-023-04815-3.
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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’s dissertation titled “Differentiation of Hemp and Marijuana Using Ag-Ligand Ion Complexation and a Semi-Quantitative Decision-Point Assay.”
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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!
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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 “Differentiation of Hemp and Marijuana Using Metal Ligand Ion Complexation.”
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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’ research was titled “Investigating the Effects of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS” and Alleigh’s research was titled “Differentiation of Δ9-THC and CBD Using Ag-Ligand Ion Complexation and ESI-MS/MS.”
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Alexis Pollard and Alleigh Couch present their research at the AAFS 75th Annual Conference
February 2023
Alexis Pollard (left) presented her capstone research titled “Investigating the Effect of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS” on Wednesday, February 15th, 2023. Alleigh Couch (right) also presented her capstone research titled “Differentiation of ∆9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS)” on Wednesday, February 15th, 2023.
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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’ capstone research titled “Investigating the Effect of Substitution Location on Fentanyl Analog Identification for Methyl-Substituted Fentanyl Analogs Using GC-EI-MS.”
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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’s capstone research titled “Differentiation of ∆9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS).”
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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).
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Alleigh Couch and Jared Sharp’s 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: 10.1016/j.ijms.2022.116964.
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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’ decisions regarding seized drug identifications based on the use of IS-CID fragment ion spectra. Available via DOI: 10.1016/j.forc.2022.100441.
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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’s research group on a variety of research projects including the differentiation of unburned smokeless powders through visual and chemical analysis. Congratulations Daniel!
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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’s 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!
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Daniel Do receives the best poster presentation awared at the 15th Annual SHSU 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 SHSU Undergraduate Research Symposium for his poster presentation titled “Differentiating Unburned Smokeless Powders through Visual and Chemical Analysis” on April 23rd, 2022.
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Jared Sharp successfully presents his capstone research
April 2022
Jared Sharp presented his capstone research titled “Identifying 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” on April 22nd, 2022.
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Jared Sharp and Ruby Liliedahl present their research at the AAFS 74th Annual Conference
February 2022
Jared Sharp presented his capstone research titled “Identifying 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” 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 “The Effects of Storage Time, Adverse Storage Conditions, and Lab Exposure on Blood Alcohol Concentrations.” 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.
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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.
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The Davidson research group grows!
September 2021
Jared Sharp (right), Alleigh Couch (center), and Daniel Do (left) join Dr. Davidson’s 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.
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Ruby Liliedahl’s manuscript accepted in Forensic Chemistry
August 2021
This manuscript is from Ruby’s 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: 10.1016/j.forc.2021.100349.
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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 YouTube.
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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 “Exhaled Breath: Exploration of an Alternative Matrix.”
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Ruby Liliedahl successfully presents her capstone research
April 2021
Ruby Liliedahl presented her capstone research titled “Differentiation of Synthetic Cathinone Isomers Using GC-EI-MS and Multivariate Analysis” on April 21st, 2021 to complete her capstone research project.
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Ruby Liliedahl presents her research at the AAFS 73rd Annual Conference
February 2021
Ruby Liliedahl presented her capstone research titled “Differentiation of Synthetic Cathinone Isomers by GC-EI-MS and Multivariate Analysis” on Thursday, February 18th, 2021 at the AAFS 73rd Annual Virtual Scientific Meeting.
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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.
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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: 10.1002/jms.4679.
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Dr. Davidson brings DART to SHSU
October 2020
Direct analysis in real time (DART) 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. SHSU now joins a growing network of academic, industrial, and government laboratories using DART-MS. DART-MS is a branch of Dr. Davidson’s ambient ionization mass spectrometry (AI-MS) research agenda here at SHSU.
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Welcome to the Team - Ruby Liliedahl
September 2020
Ruby Liliedahl joins Dr. Davidson’s 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.
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Welcome to the Team - Dr. Tyler Davidson
August 2020
Dr. Davidson joined the Department of Forensic Science at Sam Houston State University as an Assistant Professor.
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21st Annual FSF Emerging Forensic Scientist Award
April 2020
J. Tyler Davidson was awarded the 21st Annual Forensic Science Foundation Emerging Forensic Scientist Award for his presentation titled, “On the Fragmentation Behavior of Fentanyl and Its Analogs in Electrospray Ionization-Tandem Mass Spectrometry (ESI-MS/MS)”.