This application note adopted the Full Evaporation Technique (FET) to analyze the solvent residual, based on California Residual Solvents Category, in cannabis oil by a CDS Analytical 7000C concentrator equipped with a dynamic headspace (DHS) module. This setup was mounted on a PAL RTC rail and connected to a GC/MS for compounds separation and detection.
In the pharmaceutical manufacturing process, residual solvents may remain in the final product besides the active pharmaceutical ingredients (APIs). These residual solvents are not beneficial to the therapeutic treatment and are regulated by USP 467 method. In the USP 467 method, the dynamic headspace technique was used as the Gas Chromatography (GC) sample introduction method. Three procedures are followed as (1) Identification and limit test, (2) Confirmatory test and (3) Quantitative test. In the USP 467 method, the calibration standard and samples could be insoluble in water, and need to be diluted into a heavier, water-miscible solvent, such as N,N-Dimethylacetamide (DMA). These samples are further prepared by adding an aliquot of the diluted sample to water in a headspace vial for GC analysis. The process involves wet chemistry and may complicate the results with solvent effect.
On the other hand, more states in U.S. have legalized marijuana products for therapeutic and entertainment purposes. However, there are currently no federal regulations to define the allowable concentration limits residual solvent, rather than certain pioneering state-level regulations. For example, Table 1 shows the list of proposed residual solvents and action levels for cannabis products in the State of California. Based on the max allowed concentration limit, these solvents are categorized in two classes as California Residual Solvents Category I and II.
From previous applications, the Full Evaporation Technique (FET) is proven to be an exhaustive way to transfer analytes from the sample to the GC through the headspace, which eliminates the balance time and uses minimized sample amount. In this application note, a dynamic headspace system is setup to explore its capability to analyze the residual solvents in cannabis oil by FET.
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