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Advisory Committee Chair

Curt E Harper

Advisory Committee Members

Elizabeth Gardner

Robert Lockwood

Document Type

Thesis

Date of Award

2022

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

Oral fluid (OF) drug testing was first applied in the workplace and pain management facilities, and is now being applied to DUI/D (Driving Under the Influence of Drugs) cases to help establish probable cause and for laboratory evidentiary confirmation. OF drug testing is efficient due to its easy, fast, gender-neutral and OF sample collection is minimally invasive compared to blood and urine. The objective of this study is to investigate the stability of cannabinoids in OF specimens over time. Limit of detection and potential matrix and analyte interference will also be evaluated. The ANSI/ASB Standard 036 for Method Validation in Forensic Toxicology on how to evaluate interference and limit of detection was followed in this study. OF samples were collected from DUI/D subjects with a Quantisal collection device. Stability and interference studies were conducted using the ADFS OF cannabinoid assay. This method consists of a liquid-liquid extraction for delta-9-tetrahydrocannabinol (Δ9-THC), delta-8-tetrahydrocannabinol (Δ8-THC), 11-hydroxy-delta-9-THC (THC-OH), 11-nor-9- carboxy-delta-9-THC (THC-COOH), cannabidiol (CBD), cannabinol (CBN), and cannabigerol (CBG) for analysis by the Agilent 6460 or 6470 Triple Quadrupole Tandem Mass Spectrometer. Simulated and DUI case specimens were tested at time zero, two weeks, one month, 60 days, 90 days, two years, two and half years, and three years. The iv novel cannabinoids Δ8-THC and Δ10-THC were validated by assessing limit of detection (LOD), analyte interference, and matrix interference. Baseline resolution was achieved for Δ8 and Δ10-THC. An LOD was set at 1 ng/mL for both Δ8 and Δ10-THC. Δ8, Δ9, and Δ10-THC were not stable when stored at room temperature. In fact, Δ10-THC was no longer detected at 60 days. Overall, target stability was greatly enhanced with refrigeration (4⁰C). Δ9-THC was stable for up to 90 days, with overall target stability within ±20% of the concentration at time zero. Previously analyzed case samples had a median decrease of 20% when compared to the first analysis, falling within ±20% of the initial concentration. The elution buffer, collection device, analyte chemical properties, and storage conditions are all factors in the stability of drug concentrations in OF. These results illustrate the importance of continuously monitoring method performance, potential new interferents, and analyte stability of cannabinoids.

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