The Controlled Substances Act of 1970 classified the plant cannabis, historically classified as either marijuana or hemp, as an illegal drug, a Schedule I controlled substance with a high potential for abuse, and not approved for medical use by the FDA in the United States. classified into. For almost 50 years, hundreds of thousands of people have been arrested and imprisoned for possessing it.
The 2018 Farm Bill changed this simple classification of cannabis. This bill legalized forms of cannabis classified as cannabis, but forms classified as marijuana remained illegal. The law left it up to law enforcement and forensic laboratories to tell the difference, but this proved difficult, time-consuming and expensive.
Scientists use the amount of THC (one of the psychoactive components of cannabis) in the cannabis plant to distinguish between hemp and marijuana. (1) The Farm Bill defines hemp as cannabis with a total THC content of 0.3% or less. Cannabis plants containing more than 0.3% THC are considered marijuana and remain on the Schedule I substance list (Figure 1).
Cannabis regulations are further complicated by the fact that many states have decriminalized the use of marijuana. Currently, medical use of marijuana is legal in 37 states and the District of Columbia, and recreational use of marijuana is legal in 19 states and the District of Columbia. However, in the remaining states, marijuana is still considered illegal and must be distinguished from cannabis. (2) Federal law continues to consider marijuana illegal.
As a result of the Farm Bill, forensic laboratories must measure the exact amount of THC in seized evidence to distinguish hemp from marijuana. In 2022, more than 10% of all submissions to crime labs determined whether they were marijuana or hemp.
This created a new problem for the crime lab, which was already overwhelmed. How can such precise measurements be made quickly and easily when so few laboratories have the personnel, equipment, and protocols to do so?
Is it hemp or marijuana?
Two NIJ-supported laboratories are using different types of mass spectrometry to determine the exact amount of THC present in a sample: gas chromatography-mass spectrometry (GC-MS) and real-time high-resolution mass spectrometry. We approached this issue using direct analysis. DART-HRMS).
Historically, most forensic laboratories have used qualitative testing of seized cannabis samples to differentiate cannabis from marijuana. Laboratories can check the microscopic and macroscopic characteristics of the plant, screen for THC through colorimetric tests (which change color when present), use various gas chromatography techniques and thin-layer chromatography (cannabis can be tested for the presence of THC through (separating the various components of) ). However, none of these tests can measure the exact amount of THC present in a sample.
See sidebar.
Dr. Walter Brent Wilson and his team at the National Institute of Standards and Technology are using GC-MS to create a simple, robust, and cost-effective way to differentiate hemp from marijuana for local, state, and federal forensic laboratories. developed a method. They are also expanding their work to food. With support from NIJ, their research:
We identified a method to extract THC from cannabis samples. GC-MS was used in different scan modes to quantify the amount of THC in cannabis samples. (3) Single-ion monitoring mode was found to have dramatically improved sensitivity compared to full-scan mode.
Dr. Rabbi Musa's lab at the State University of New York at Albany took a different approach to this problem. The lab used DART-HRMS to quantify the amount of THC in complex materials that are difficult to study, such as edibles, beverages, and plant materials. This method can be performed directly on samples with minimal or no sample preparation. Their projects:
We established a rapid triage approach to detect cannabis-related molecules. Cannabinoids (the two main ones are THC and CBD) were extracted and DART-HRMS was used to differentiate them. A validated protocol to measure the amount of cannabinoids detected.
A University at Albany team has shown that DART-HRMS can be used to rapidly detect THC and other cannabis-related molecules in baked goods, candies, beverages, and plant materials with minimal preprocessing steps. . They also identified the limitations of using DART-HRMS to detect THC in different types of samples.
Impact on forensic laboratories
Dr. Musah believes that the increased speed of detecting THC in cannabis samples using DART-HRMS has the potential to reduce sample testing backlogs and chemical reagent costs and streamline sample analysis protocols. I expect that there will be.
Dr. Wilson's project created a standard operating procedure for quantifying THC in federal, state, and local forensic laboratories. His research team shared their findings through webinars and publications, and created a training model for the Montgomery County Police Department and Maryland State Police crime lab on THC quantification using GC-MS.
About this article
The research described in this article was supported by NIJ Interagency Agreement Number DJO-NIJ-20-RO-0009 awarded to the National Institute of Standards and Technology and NIJ Grant Number 2019 awarded to the National Institute of Standards and Technology. -Supported by DU-BX-0026. University at Albany, State University of New York. This article is based on these award reports, “Accurate THC Determination on Seized Cannabis Samples for Forensic Laboratories” (PDF, 26 pages) by Dr. Walter Brent Wilson. “Research to develop a validated method for THC quantification in complex matrices by high-resolution DART-MS – Research focused on edibles and plant materials” by Dr. Rabi A. Musah (PDF, 18 pages) )
Side note: How is mass spectrometry used in cannabis analysis?
Mass spectrometers allow scientists to calculate the precise molecular weight of substances and identify known and unknown compounds.
One type of mass spectrometry, gas chromatography-mass spectrometry (GC-MS), combines the capabilities of gas chromatography and mass spectrometry to identify different substances in a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation, food and flavor analysis, and unknown sample identification.
Another type of mass spectrometry, real-time high-resolution direct analysis (DART-HRMS), combines the capabilities of real-time direct analysis with high-resolution orbitrap mass spectrometry to identify different substances within a test sample. DART-HRMS allows scientists to quickly obtain accurate mass measurements on a high-resolution mass spectrometer without any separation steps. Applications of DART mass spectrometry include pharmaceutical research, forensic research, quality control, and environmental research.
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