NIR spectroscopy for rapid measurement of moisture and cannabinoid contents of industrial hemp (Cannabis sativa)

With the legalization of industrial hemp in the United States, defined based on tetrahydrocannabinol (THC) dry weight content of ≤ 0.3%, the market for various cannabinoids including cannabidiol (CBD), cannabinol (CBN), cannabigerol (CBG), and cannabichromene (CBC) have flourished. The current measurement methods such as ultra-high performance liquid chromatography and gas chromatography (GC) require sophisticated instruments and trained personnel and are time-consuming. Therefore, there is a critical need for a rapid and reliable method to measure cannabinoids for regulatory compliance, determination of usage, and for quality control. Here, we report the use of near-infrared spectroscopy (NIRS) for rapid measurement of moisture content (MC) and cannabinoid contents of ground and whole hemp and rapid identification of legal from illegal industrial hemp. Good NIRS quantitative predictions were obtained for MC of ground and whole hemp, THC of ground hemp, CBD of ground and whole hemp, and CBC of whole hemp. Binary classification of industrial hemp as legal (≤0.3% THC) or illegal was performed using discriminant analysis and thresholding models. Discriminant calibration models developed showed correct classifications (CC) ranging from 93.0% to 94.0% with CC for independent validation at 83.9–87.5%. The concurrent multi-constituent predictions of MC and THC using NIRS allows for real-time adjustments of cannabinoid contents and rapid identification of legal or illegal hemp. These are important tools that will benefit the hemp industry, regulators, farmers, and consumers.