Cannabinoids in edibles and cosmetics : analytical approaches and applications

Abstract

Cannabinoids are increasingly incorporated into consumer products such as edibles and cosmetics, creating demand for validated and reliable analytical techniques that can accurately determine their content within complex matrices. The aim of this study was to develop and validate a reproducible high-performance liquid chromatography (HPLC) method for the quantification of major cannabinoids in cosmetic formulations, supported by a systematic review of existing chromatographic approaches. The study was conducted in three phases. First, a systematic literature review was carried out using PubMed to identify analytical methods for cannabinoids in edible and cosmetic matrices. Out of 157 records, 16 articles met the inclusion criteria, demonstrating the predominant use of HPLC and gas chromatography (GC), but also revealing inconsistent validation practices, particularly in cosmetic applications. The second and third phase was experimental work conducted respectively to develop and validate a laboratory-based HPLC method tailored for cosmetic products. The study was conducted at the Pharmaceutical Synthesis and Technology Laboratory, Department of Pharmacy, University of Malta. Method development focused on optimising sample preparation. Five solvents were evaluated, with 95% ethanol selected for its reproducible solubilisation, stable baselines, and minimal chromatographic interference. A sample mass of 0.1 g was found optimal to avoid viscosity issues, while centrifugation at 10,000 revolutions per minute (rpm) for 10 minutes produced clear extracts more consistently than winterisation. Homogenisation was achieved by vortexing and sonication, ensuring reproducible recovery across creams, gels, and balms. Separation of five cannabinoids; cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), delta-9-tetrahydrocannabinol (THC), and tetrahydrocannabinolic acid (THCA) was achieved using a C18 column with acetonitrile–acetic acid mobile phase and ultraviolet (UV) detection at 220 nanometres. Validation followed International Council for Harmonisation (ICH) Q2(R2) guidelines1 . The method demonstrated specificity, linearity (coefficient of determination R² > 0.9998), accuracy within 82–96% recovery, and precision, with relative standard deviation (RSD) values well below 2%. Limits of detection were 6.25 µg/mL (0.000625%) and limits of quantification were 12.5 µg/mL (0.00125%) for all five cannabinoids.The validated method was applied to 10 commercial cosmetic products labelled as containing cannabinoids, to determine CBD concentrations. Discrepancies were found between measured and declared content: some products contained only 12% of the stated CBD concentration, while others exceeded label claims by up to 14%. No undeclared cannabinoids, including THC, were detected. This study highlights ongoing quality control challenges in the cannabinoid cosmetics sector and provides a validated, practical HPLC protocol for routine testing. Study findings can help supportregulatory oversight, accurate labelling, and quality assurance.