The Utilization of Capillary Microextraction of Volatiles Coupled with Portable Instrumentation for the Analysis of Volatile Organic Compounds for Forensic Applications

Authors

Jacqueline L. RodriguezFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Chemistry

First Advisor's Name

Kenneth Furton

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Anthony DeCaprio

Second Advisor's Committee Title

Committee member

Third Advisor's Name

David Becker

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Raphael Raptis

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Norman Munroe

Fifth Advisor's Committee Title

Committee member

Keywords

Volatile Organic Compounds, Capillary Microextraction of Volatiles, CMV, GC-MS, gas chromatography

Date of Defense

3-27-2023

Abstract

Similar to the way canines search for illegal substances, the volatile analytes that are naturally emitted from illicit materials can be analytically detected to alert for the presence of contraband. In this study, a dynamic sampling and preconcentration device, capillary microextraction of volatiles (CMV), is coupled to portable instrumentation for the rapid field detection of volatile organic compounds (VOCs) associated with drugs and explosives. By coupling the CMV device to a portable gas chromatograph-mass spectrometer (GC-MS), sub-nanogram (ng) instrumental detection limits were achieved for VOCs associated with cocaine and VOCs associated with smokeless powder explosives. Three different dynamic sampling methods were used with the CMV to sample the volatiles before analysis: closed-system headspace sampling, single-injection simulated open-air vapor sampling, and a novel continuous vapor delivery and sampling system, that was constructed to facilitate the gradual delivery of sub-nanogram quantities of the VOC analytes of interest. The new continuous delivery system achieved significantly higher recoveries for all the analytes while requiring less sampling time (~ 5 minutes) and sampling volumes.

Furthermore, hemp and marijuana are both derived from the same plant, Cannabis sativa. However, hemp is legal to grow and distribute in the U.S, legally defined as cannabis plants that contain < 0.3% w/w Δ9-tetrahydrocannabinol (THC), while marijuana (≥ 0.3% w/w of THC) remains a Schedule I DEA controlled substance. In this portion of the study, the VOCs from the headspace of authentic hemp and marijuana plants were extracted and preconcentrated using the CMV followed by analysis with a GC-MS, to determine any differences between their VOC profiles.

Another portable instrumentation, a hand-held ion mobility spectrometer (IMS), was used for the vapor detection of explosives and illicit drugs. The portable IMS possesses a rapid analysis time of ~ 20 ms and was coupled to a stainless-steel wire mesh coated with ph-PDMS (phenyl-terminated polydimethylsiloxane), to enhance vapor detection. These new, fast, and sensitive sampling methodologies coupled with the rapid analysis of field-portable instruments expand the potential applications of the CMV for the field detection of trace analytes associated with illicit drugs and explosives.

Identifier

FIDC011024

ORCID

https://orcid.org/0009-0007-2940-477X

Previously Published In

J.L. Rodriguez, J.R. Almirall, Continuous vapor sampling of volatile organic compounds associated with explosives using Capillary Microextraction of Volatiles (CMV) coupled to a portable GC-MS, Forensic Chem. (2021).

Recommended Citation

Rodriguez, Jacqueline L., "The Utilization of Capillary Microextraction of Volatiles Coupled with Portable Instrumentation for the Analysis of Volatile Organic Compounds for Forensic Applications" (2023). FIU Electronic Theses and Dissertations. 5299.
https://digitalcommons.fiu.edu/etd/5299