COLORIMETRIC DEVICE FOR QUANTITATIVE DETERMINATION OF CANNABINOL (CBN) IN CANNABIS FLOWER USING PORPHYRIN-MEDIATED SILVER NANOPARTICLES

Abstract

Cannabinol (CBN), a degradation product of tetrahydrocannabinol (THC), is an important analytical marker to determine the composition and quality of cannabis flowers. In this work, porphyrin-mediated silver nanoparticle (Por-AgNP) colorimetric platform was developed for the rapid and quantitative determination of CBN, which could be used as a portable cannabis analysis. Chemical reduction of AgNO₃ with NaBH₄ in the presence of the porphyrin ligand was used to prepare por-AgNPs and characterize them using UV-Visible spectroscopy, FTIR, TEM and DLS. The characteristic absorption maximum for the nan Particles was found to be around 430 nm, their morphology was found to be close to spherical shape, their mean TEM diameter was 32.61 ± 5.17 nm and their mean hydrodynamic diameter was about 62.31 nm. The plasmonic sensing was found to be concentration dependent as the CBN concentration increased from 1 μM to 100 μM, the plasmonic response increased from 0.10310 to 0.97380 AU. The recoveries were around 96.20-102.80% when accuracy assessment was performed. The colorimetric method was also tested on samples of cannabis flower with CBN content with HPLC-DAD being used as a reference method. A portable prototype was incorporated with an LED, photodetector and microcontroller to convert the optical response to an electronic signal, resulting in an increase from 180.48 mV for the blank to 764.99 mV at 100 µM CBN. The results indicate the viability of Por-AgNPs as a low cost, fast and field deployable method for CBN determination and provide the stepping stone towards field deployable cannabis quality assessment. Further validation with authentic samples, and experimentally determined analytical figures of merit is recommended.