Chemistry & Biochemistry Colloquium

TITLE: Matrix-Tolerant Quantification of THC and THCA in Complex Cannabis Products Using In-Sample Calibration The guest speaker for the November 4th Chemistry & Biochemistry Colloquium will be Dr. Yanfang Li. Dr. Li is a Postdoctoral Researcher in Professor Mengliang Zhang's research group in the Department of Chemistry and Biochemistry at Ohio University. ABSTRACT Accurate quantification of Δ9-tetrahydrocannabinol (THC) and Δ9-tetrahydrocannabinolic acid (THCA) in cannabis- and hemp-derived products remains challenging due to complex sample matrices, significant matrix effects, and wide variations in analyte concentrations. Conventional LC-MS/MS methods often rely on external calibration curves and matrix-matched standards, which can be labor-intensive and difficult to apply across diverse product types. In this study, we developed an in-sample calibration curve (ISCC) approach based on multiple isotopologuereaction monitoring (MIRM) for THC and THCA quantification without external calibration curves. By leveraging the predictable natural isotopic abundances of stable-isotope-labeled calibrators, the method generates multiple calibration points directly within each sample. The method demonstrated excellent linearity (R² > 0.999), precision (<10% RSD), and accuracy (within ±10%) across diverse cannabis-derived products, with strong agreement with conventional external calibration. These results demonstrate the potential of ISCC for reliable, matrix-tolerant cannabinoid