Not what it seems: analytical validation and label accuracy of commercial CBD oils using HPTLC.

Abstract

The rapid growth of the cannabidiol (CBD) market has raised concerns about product labeling accuracy and quality control. This study aimed to validate a high-performance thin-layer chromatography (HPTLC) method and apply it to analyze CBD content in commercial oils and e-liquids available in Costa Rica. The HPTLC method was validated following guidelines of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use. Performance parameters assessed included linearity, accuracy, precision, specificity, and limits of detection (LOD), and quantification (LOQ). After validation, the method was used to quantify CBD and screen for other phytocannabinoids such as CBG, CBN, and Δ⁹-THC in 5 commercial oils and 3 e-liquids. The method showed excellent linearity (R² > 0.9998), precision (%CV < 2%), and accuracy (99–102% recovery), while successfully detecting CBD concentrations and qualitatively identifying other cannabinoids. Notably, some commercial samples showed CBD over- and underlabeling, and tentative presence of Δ⁹-THC. These findings reveal inconsistencies between the labeled and actual CBD content in several products, mirroring international trends, and represent the first documented evidence of mislabeling in hemp-based products in Costa Rica. The validated HPTLC method offers a cost-effective tool for regulatory surveillance, enabling preliminary cannabinoid profiling and quantification. Its application can support public health policies and consumer protection through improved product transparency and compliance with Costa Rica’s national hemp regulations.