Analysis of Contaminants in Hemp Using Liquid Chromatography Coupled to Tandem Mass Spectrometry

Hemp is a class of cannabis sativa that contains significantly lower levels of tetrahydrocannabinol (THC) (below 0.3% on a dry weight basis), and may have higher levels of cannabidiol (CBD). This agricultural commodity is being utilized as a source of fiber, protein, and cannabinoids. The 2018 Farm Bill authorized the production and distribution of hemp under federal law, and this led to a significant increase in the development and commercialization of hemp products. Like cannabis and other crops, dried hemp plant material may contain various contaminants that are harmful to humans. For this reason, robust analytical workflows capable of detecting low concentrations of pesticides and other contaminants in hemp and cannabis plant material are highly desired. This work describes a complete workflow for the analysis of diverse contaminants (i.e., pesticides and mycotoxins) in hemp. Briefly, hemp samples were pulverized and extracted with acidified acetonitrile. Afterwards, extracts were cleaned up by passing them through solid phase extraction (SPE) cartridges to remove major interferences. Instrumental analysis was conducted using liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS). A Raptor ARC-18 column (150 x 2.1 mm, 2.7 µm) was used for analyte separation over a 21 min gradient. Target contaminant recoveries ranged from 68 to 120% in hemp samples spiked at 100 ppb. Satisfactory results in terms of LOQ, linearity, accuracy, and precision were obtained for all the tested contaminants. Overall, the presented workflow provides a reliable and easy approach to quantify multiple contaminants in hemp samples.