Preparation of ZIF-8 grafted magnetic solid-phase extraction sorbent for sensitive determination of four cannabinoids in urine and oral fluid

Background The global increase in cannabis use has created a strong demand for reliable and efficient detection methods. Traditional urine-based assays are widely used and standardized, but suffer from complex hydrolysis requirements, long detection windows, and an inability to monitor recent use. In contrast, oral fluid testing enables non-invasive, real-time detection of parent cannabinoids, but is limited by low sample volume, matrix interference, and insufficient sensitivity in common rapid tests. It is clear that a sample preparation and detection approach is needed that is robust, highly sensitive, streamlined, and compatible with high-throughput confirmatory analysis such as LC-MS/MS. Results In this study, a magnetic solid-phase extraction (MSPE) method was developed using a novel magnetic metal–organic framework composite, Fe 3 O 4 @poly(GMA/DVB-ZIF-8), for the efficient extraction of four cannabinoids from urine and oral fluid. The sorbent uses multiple interactions—including hydrophobic, π–π, electrostatic, and Zn–O coordination—to achieve high analyte recovery (exceeding 85%). Coupled with UHPLC-MS/MS analysis, the method demonstrates wide linearity (0.05–25 ng/mL, r 2  > 0.9945), low detection limits (as low as 0.017 ng/mL), and good repeatability (RSDs <13.8%). Comparative evaluation with conventional liquid–liquid extraction showed minimal deviation (relative percent difference <6.0%), confirming high trueness and reliability for cannabinoid monitoring in biological samples. Significance This MSPE approach provides a simple, efficient and high-throughput sample preparation method for reliable and rapid forensic analysis of cannabinoids in complex biological samples.