Publication Date

Spring 2026

School

School of Health Sciences

Major

Forensic Science

Keywords

Tetrahydrocannabinol, THC metabolites, LC-MS/MS, Urine Extraction

Abstract

Over the past few decades, widespread cannabis legalization has substantially increased forensic toxicology casework throughout the United States (National Institute of Justice, 2019). Washington state, an early adopter of recreational cannabis legalization, reflects this trend with toxicology laboratories reporting a 59% increase in annual case submissions since 2014 (Goldstein-Street, 2026). Current cannabinoid analysis methods involving liquid – liquid extraction (LLE) coupled with gas chromatography – mass spectrometry (GC-MS) are time consuming, labor-intensive, and require chemical derivatization and pH modification prior to analysis. To manage growing caseloads, an efficient method capable of consistently and reliably detecting THC is critical. The goal of this study is to develop and optimize a method using supported–liquid extraction (SLE) coupled with liquid chromatography–tandem mass spectrometry (LC-MS/MS) for the detection of Δ⁹-THC-COOH and Δ⁸-THC-COOH in urine (Figure 1). An initial procedure is proposed and then systematically altered based on its chromatographic performance until an optimized procedure is produced. Each proposed method is evaluated on peak shape, signal intensity, and consistency relative to test mix standards. The final optimized procedure produced sharp, symmetrical peaks with high signal intensity, demonstrating consistent retention times and the reliable detection of Δ⁹-THC-COOH. Although chromatographic peaks exhibited overlapping, partial differentiation between Δ⁹-THC-COOH and Δ⁸-THC-COOH is achieved. In conclusion, the optimized SLE – LC-MS/MS procedure is faster, more efficient, and reliable as compared to traditional LLE – GC-MS. With further optimization, this method has the potential for high-throughput forensic toxicology applications, decreasing the burden of cannabis legalization on the criminal justice system.

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