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This application note demonstrates the CEM MARS 6 for microwave digestion of mixed cannabis and hemp containing products in a single run and elemental analysis of these products.

Microwave Digestion and Elemental Analysis of Cannabis and Hemp Products

In 1970, marijuana was designated a Schedule 1 drug, under the Controlled Substances Act, making it nearly impossible for laboratories to perform cannabis research. However, medicinal use of cannabis is now legal in Canada and 33 U.S. states. With the passage of the Farm Bill in 2018, it is now federally legal to grow and process hemp in all 50 states. All of this interest in medical cannabis and cannabidiol (CBD) has highlighted the need for good analysis methodology in this relatively young market. Cannabis analysis is still developing standardized protocols, requirements, and acceptable testing practices. Typical testing requirements for cannabis and its products include analysis of heavy metal, pesticide residues, and the potency of active ingredients such as tetrahydrocannabinol (THC). The terpene content of cannabis is also important. Terpenes have been shown to have beneficial uses for treatment of conditions ranging from cancer and inflammation to anxiety and sleeplessness. It is believed that the combination of terpenes and cannabinoids in cannabis produce a synergistic effect with regards to medical benefits.

	Certain heavy metals can cause adverse effects on human health. Toxic heavy metals such as arsenic, cadmium, lead, and mercury are persistent once released into the environment and can accumulate in cannabis plants. Since hemp is a strain of cannabis that contains very little THC, it is susceptible to bioaccumulation of heavy metals like its THC-containing relative. Cannabis-based products such as foods, oils, tinctures, and salves should be tested for the presence of heavy metals to ensure patient safety and product quality. Cannabis and CBD-infused products have grown in popularity in states that allow recreational use of cannabis and hemp. This application note details the digestion and analysis of various forms of hemp and cannabis products.

	A CEM MARS™ 6 microwave digestion system was used to digest the varied cannabis and hemp sample types. The MARSXpress™ Plus vessels with disposable glass inserts uses a vent and reseal design, which allows for acid vapors to be exhausted while maintaining the sample integrity and elements within the vessel. The 110-mL vessel volume provides for a larger headspace, allowing a larger sample size for a more homogenous sample. The MARSXpress Plus vessel design uses only three pieces that are easily assembled and placed in a 24-position turntable, prior to placing into the MARS 6 system. The glass insert provides an inexpensive disposable vessel that eliminates the need for vessel cleaning.

	All samples required special preparation, based on the qualities of each sample, in order to obtain a homogenous 0.25 g approximate sample weight. It is important to carefully deposit the oil, cream, and peanut butter, in order to not get the sample stuck to the sides of the vessel. For peanut butter and cream, a long plastic spatula was used to deposit the sample on the bottom of the liner. For the oil, the sample was deposited to the bottom of the vessel with a plastic pipette. Then, the inside of the liner was washed down with the acid to make sure all the sample got to the bottom. Table I shows the seven samples that were digested and the preparation method used, prior to placing them into the vessels.

 was added to each vessel and then allowed to predigest for 15 min prior to sealing and placing the vessel in the turntable. The turntable was then placed in the MARS 6 and the Glass Cannabis One Touch™ Method was chosen on the touchscreen. The MARS 6 then counted the number of vessels and applied the precise power required to achieve the optimal digestion temperature of 200 °C. This temperature ensured the complete digestion of the samples, prior to analysis.

	Samples were prepared in two batches. One batch was spiked with a spike solution containing between 0.4 and 1 ppm As, Hg, Cd, and Pb. The second batch was left unspiked. All samples were run in triplicate with blanks in each run. Upon successful digestion all samples were diluted to 50 mL with deionized water for analysis.

	All samples were analyzed on an Agilent 5110 ICP-OES to determine spike recoveries and actual sample content of the "big four" heavy metals of As, Cd, Hg, and Pb. Instrument conditions are detailed in Table II.

	The MARS 6, with MARSXpress Plus vessels with disposable glass inserts, was able to successfully digest all samples in a mixed batch. All of the samples were completely digested, yielding clear and particulate-free solutions upon dilution with deionized water. The MARS 6 is an ideal digestion system for the cannabis industry because it is able to successfully digest batches of mixed materials, including foods, oils, tinctures, creams, and plant materials, in as little as 35 min.

	After confirmation of the method through a spike recovery study, unspiked samples were analyzed for their total trace metals content using the same technique. Table IV shows the trace metals content of unspiked samples. Table V contains the California action levels for medical cannabis samples. It is worth noting that all of the unspiked samples contained far less than the maximum allowable limit for each element.

	The MARS 6 with MARSXpress Plus vessels with disposable glass inserts was able to digest a wide variety of cannabis and hemp samples in mixed batches producing digestate that was suitable for analysis. Analysis of all samples showed excellent spike recovery and gave great confidence in the actual levels of trace metals in the unspiked samples.


	P.O. Box 200, Matthews, NC 28106
	tel. (704) 821-7015, fax (800) 726-3331
	Website: 

Microwave Digestion and Trace Metals Analysis of Cannabis and Hemp Products

http://www.spectroscopyonline.com/spec_w/cannabis_analyses

	Better analytical results begin with better sample preparation. Due to the complex nature of the cannabis plant, a complete and reliable analysis can be difficult to achieve. The first step to any analysis is to ensure a complete digestion or extraction in the sample preparation. In this webcast, you will learn techniques and tools for fast, efficient, and reproducible sample preparation for all your LC–MS, GC–MS, and ICP–MS analyses of cannabis and hemp samples. Discussions on the methods and techniques for extraction of pesticides and THC from plant material, and microwave digestion of mixed samples including flower, edibles, lotions, extracts, and oils will be addressed. In addition, valuable sample handling techniques for achieving more consistent and homogenous sampling and comparisons between classic and automated techniques and low and high throughput options will be covered.

		Learn simple and repeatable sample preparation techniques for cannabis and hemp products

		Understand the importance of temperature controlled potency and pesticide extractions through filtration and cooling

		Best practices for single batch microwave digestion of all cannabis and hemp samples including flower, foods, lotions, oils, and extracts

	Speakers: Alicia Douglas Stell, Ph.D., Lead R&D Scientist, Molecular Sample Preparation Division, CEM Corporation

	Bob Lockerman, Global Product Manager, Analytical Division, CEM Corporation

Wednesday, Jul. 24, 2019 at 11am EDT | 8am PDT | 4pm BST | 5pm CEST

	On demand available after airing until Jul 24, 2020

Better analysis starts with better sample prep, particularly with challenging samples like cannabis and hemp. Learn how to optimize techniques and tools to achieve consistent and complete sample prep for potency, pesticides, and metals analysis.

Live: Wednesday, Jul. 24, 2019 at 11am EDT | 8am PDT | 4pm BST | 5pm CEST 
On demand available after airing until Jul 24, 2020 

Register free

Potency, Pesticides, and Metals, Oh My! Achieving Superior Cannabis Analyses with Simple Sample Prep Tools

The new USP Chapters <232> and <233> will become official on January 1, 2018 and bring significant changes in sample preparation and analysis of pharmaceutical samples both in excipients and APIs. Certain APIs pose challenges to acid digestion because they are very stable compounds and not easily broken down.

	USP methods <232> and <233> call for total digestion of pharmaceutical samples and quantification of individual elements. Many pharmaceutical materials can be easily digested but APIs with multiple aromatic ring structures can be very difficult to completely break down and obtain a clear digestion, as prescribed in the new chapters. Microwave digestion can provide a solution to many of these compounds.

	This application note will focus on the use of the CEM MARS 6 microwave digestion system and new high performance iPrep vessels to completely digest very difficult APIs. The ring structures of the APIs are shown to illustrate the high stability of these compounds. The sample sizes listed represent the maximum allowable in order to achieve a complete digest.

	Three APIs were prepared using a CEM MARS 6 microwave digestion system equipped with iWave technology and iPrep vessels.

	iWave is a novel Light Emitting Technology(tm) that measures the temperature of the actual sample solution inside the vessel and does not require an internal probe.

	iPrep is a simple to use three-piece vessel which uses a simple hand torque device to seal. The patented dual-seal design provides for higher temperatures and fine control of the vent and reseal process necessary for these sample types.

	Each API sample was weighed and added to an iPrep liner with 9 mL HNO

 and 1 mL HCl. The vessels were capped, assembled, and placed in the MARS 6 for digestion. Digestion parameters are recorded in Table I.

	The MARS 6 with iPrep vessels was able to completely digest each of the API materials and provide a clear solution. Of note is that the TrixiPhos digestate is a bright yellow color. This is a result of the Pd catalyst used when synthesizing the compound. Each API sample was run in duplicate in order to confirm the success of the sample preparation. All samples were completely digested as shown in Figure 1.

	The MARS 6 system with iPrep vessels is an ideal option for working with these difficult pharmaceutical materials.


	P.O. Box 200, Matthews, NC 28106
	tel. (704) 821-7015, (800) 726-3331
	Website: 

Author | CEM Corporation

Articles

Microwave Digestion and Elemental Analysis of Cannabis and Hemp Products

Microwave Digestion and Trace Metals Analysis of Cannabis and Hemp Products

Potency, Pesticides, and Metals, Oh My! Achieving Superior Cannabis Analyses with Simple Sample Prep Tools

Digestion of Difficult APIs in Accordance with USP