Cannabis Products and Contaminant Detection: Critical Review of Regulatory Oversight and Analytical Methodologies

INTRODUCTION: Cannabis legalization and consumption in the United States have accelerated over the past decade, resulting in a rapidly diversifying marketplace of medical and adult-use products. As of 2025, medical cannabis is permitted in 47 states, while adult-use markets are authorized in 24 states and the District of Columbia. This expansion underscores the urgent need for robust and consistent safety testing to ensure consumer protection. Despite federal prohibition, states have independently developed their own regulatory frameworks for contaminant testing, leading to wide variability in allowable limits, analyte lists, and method validation requirements. METHOD: This review critically compares contaminant regulations across U.S. adult-use jurisdictions and evaluates analytical methodologies published between 2020 and 2025 for four major hazard categories: heavy metals, pesticides, mycotoxins, and residual solvents. Emphasis is placed on sample preparation strategies, analytical instrumentation, and method performance parameters relevant to complex cannabis matrices such as flower, concentrates, and infused products. RESULTS: Sample preparation approaches are tailored to matrix complexity and frequently utilize Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction followed by dispersive solid-phase extraction (dSPE). Cartridge SPE is commonly applied for enhanced cleanup, and immunoaffinity columns is used for selective isolation of aflatoxins and ochratoxin A. Instrumental analysis typically relies on Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for trace metals, liquid chromatography-tandem mass spectrometry and gas chromatography-tandem mass spectrometry (GC-MS/MS) for pesticide and mycotoxin detection, and headspace GC with flame ionization detection or GC-MS for residual solvent quantification. DISCUSSION: Although current methodologies provide sensitive and reliable detection, inconsistencies in regulatory oversight across jurisdictions limit data comparability and complicate interstate commerce. Establishing harmonized performance criteria, standardized reporting units, and national proficiency testing programs would improve method reliability and consumer confidence. Continued innovation in sample preparation and validated multi-residue methods will be critical as product diversity and testing demands continue to expand.