Defense Date
2025
Document Type
Directed Research Project
First Advisor
Emanuele Alves
Second Advisor
Christopher Ehrhardt
Third Advisor
Laerissa Reveil
Fourth Advisor
Ana Pego
Abstract
With the increased legalization of cannabis, the need for a rapid and reliable roadside test to determine the intoxication of drivers is paramount. This research focused on the development of a 3D-printed cartridge combined with the colorimetric dye Fast Blue for the detection of Δ9-tetrahydrocannabinol (Δ9-THC), cannabinol (CBN), and cannabidiol (CBD). Liquid cannabinoid solutions of varying concentrations were analyzed alongside multiple Fast Blue matrices, including a dry down system of Fast Blue and DI water, Fast Blue and Agar, and Fast Blue and synthetic gelatin. The overall efficacy of Fast Blue B (FB-B) and Fast Blue BB (FB-BB) as a colorimetric detection system for the presence of cannabinoids was evaluated through multiple experiments, including dye concentration analysis, drop-size tests, variability tests, calibration curve construction, L*a*b* color analysis, and fluorescence analysis. Images were collected using both a flatbed scanner and a 3D-printed photo box. Images were analyzed using ImageJ to quantify color changes, yielding analytical signals or intensity values. The results of the experimentation found that the combination of synthetic gelatin and FB-B and FB-BB provided the lowest overall variability between replicate cartridges across the three tested layer systems. The combination of FB-B and synthetic gelatin showed possible linearity (R2=0.55, r=0.74) with a small overall intensity range (11.4-11.9). Strong intensity readings were obtained from 10-100 ng, showing a low limit of detection for this system. The combination of FB-BB and the synthetic gelatin resulted in evidence of linearity (R2=0.94, r=0.97) with a larger intensity range (6.15-7.65). Strong intensity readings were detected with this system (10-100 ng). Regarding cannabinoid differentiation, the FB-B and synthetic gelatin showed promising results in the L*a*b* color space, which was used to model the cartridges' hue spatially in 3D. By modeling three replicates for each tested cannabinoid (CBD, CBN, and THC), two main clusters emerged: one with CBD and another with Δ9-THC and CBN. This showed preliminary cannabinoid selectivity based on hue differentiation. The FB-BB and synthetic gelatin systems were tested to determine whether fluorescence-based cannabinoid differentiation could be detected. No significant differences in the fluorescence of the cannabinoids with FB-BB were observed. Overall, this research provides a first step toward developing a portable detection tool for the presence of cannabinoids, using low-cost, readily available materials.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
12-8-2025