Spectral analysis separates CBD levels and flags synthetic adulterant signals

The quality control of commercial Cannabis sativa oil extracts poses analytical challenges due to their complex phytochemical composition, lipid matrix interference, and the risk of adulteration with synthetic cannabinoids. This study evaluated the applicability of two-trace two-dimensional correlation spectroscopy (2T2D-COS) combined with principal component analysis (PCA) for the quality control of full-spectrum cannabis oil extracts, addressing two objectives: detection of MDMB-4en-PINACA adulteration using UV-Vis spectroscopy and discrimination of CBD concentrations using ATR-FT-IR spectroscopy. Sixteen commercial oil samples were analyzed by HPLC-UV, revealing that only 31.2% met their declared CBD concentration within a ± 10% tolerance. UV-Vis 2T2D-COS asynchronous maps resolved the overlapping spectral contributions of CBD and MDMB-4en-PINACA in complex oil matrices, and PCA applied to vectorized 2T2D-COS maps (PCA-2D) improved group separation compared to conventional one-dimensional PCA (PCA-1D), with a 6.5-fold increase in inter-group Euclidean distance and an improvement in adulterated cluster cohesion, although dispersion-normalized metrics (Mahalanobis distance) and population-level multivariate tests showed no equivalent gain. In the ATR-FT-IR domain, diagnostic vibrational markers of CBD were identified at 1624, 1579, 1050, 1028, and 883 cm-1. PCA-2D applied to 2T2D-COS maps produced an approximately 10.3-fold amplification of inter-group spatial separation compared to PCA-1D, with enhanced discrimination of high-CBD samples. These results demonstrate that 2T2D-COS spectroscopy is an accessible strategy for cannabis oil quality control that requires only standard spectroscopic instrumentation and a reference spectrum, without complex sample preparation.