Jessica McKeil   |   October 12, 2020

Nuclear Magnetic Resonance for Potency, Profile, and Fingerprinting

NMR promises a cheaper, more accurate, and faster method to profile cannabis.
Jessica McKeil is a freelance writer focused on the medical marijuana industry, from production methods to medicinal applications. She personally found relief through cannabis for the treatment of her panic and anxiety disorder. She is lucky…

Alongside cannabis legalization comes the mandatory testing requirements, implemented throughout all layers of the industry. Although consumers may believe otherwise, the testing sector is far from settled on a single technology or approach.

Different markets (and even individual laboratories and chemists within those markets) may work with mixed methodologies. Two of the most common approaches include mass spectrometry and chromatography. But a third approach, nuclear magnetic resonance (NMR), is gaining traction as a cost-effective, faster, and accurate option.

Although NMR may sound like technology more useful for the space program than for the cannabis industry, it may offer something new within the cannabis testing space. It's not only fast and accurate; it may be able to truly fingerprint individual cultivars — something current testing technologies have yet to accomplish.

NMR promises a cheaper, more accurate, and faster method to profile cannabis, but with an industry already reliant on several other models, like mass spectrometry, will this advanced testing method catch on?

Nuclear Magnetic Resonance (NMR) Spectrometry: The Basics

First established in 1938, nuclear magnetic technology is an accepted chemical analysis tool now used across various sectors. According to one review of NMR within medical and dental fields, "The basic principles of NMR are that the structural and chemical composition of different substances can be determined by their nuclei, which have their distinctive magnetic field." In essence, NMR technologies assess the local magnetic fields around various atomic nuclei to determine a molecule's structure. Each molecule has a different magnetic field, and can then be identified and categorized.

NMR technology is widely used in the oil industry and medical analysis, and is the foundation of organic chemistry. It wasn't until the 1990s that the technology moved outside scientific circles into commercial applications. Most recently, researchers have begun applying NMR spectrometry to cannabis. This move has led to improved throughput, better pattern recognition, and a range of testable products.

As per Peter de B. Harrington, Director of the Center for Intelligent Chemical Instrumentation at Ohio University, in an interview for Analytic Cannabis, one of the most exciting aspects of NMR technology in cannabis is the pattern recognition within the NMR spectrum. He calls this the fingerprint, where key peaks "correspond to the pharmacological properties, the geographical location, strain, and hybrid, or quality."

NMR spectrometry promises faster, cheaper testing for a comprehensive spectrum of compounds. With the invention of benchtop NMR devices, the technology has become immensely more accessible and valuable for applications such as cannabis organic chemical analysis, the foundation of the cannabis testing sector.

The Benefits of NMR Technology for Cannabis Fingerprinting

Currently, the legal cannabis sector requires a detailed analysis of potency, chemical profile, and contamination. Typically, third-party laboratories rely on a suite of technologies to this end, including but not limited to:

  • HPLC (high-performance liquid chromatography)
  • UHPLC (ultra-high-performance liquid chromatography)
  • LCMS (liquid chromatography-mass spectrometry)
  • LC-MS/MS (liquid chromatography-tandem mass spectrometry)
  • GCMS (Gas chromatography-mass spectrometry)
  • ICPMS (Inductively coupled plasma mass spectrometry)

Unlike these standard technologies, which may heat or dissolve samples in a solvent during processing, NMR is nondestructive. The sample that goes in comes out intact. So while NMR spectrometry requires larger sample sizes than more conventional methods, it is no more wasteful or costly in terms of inputs.

NMR spectrometry also holds the potential to reduce the sheer number of tests and testing equipment required. ICPMS may work for heavy metals testing, but GC-MS is best for terpenes and HPLC for cannabinoids. Three different technologies target three separate cannabis compounds and contaminants. There is the potential for NMR to solve all of these at once. Work has already been done with NMR for cannabinoid analysis, and other industries use NMR analysis for heavy metals and terpenes. 

Finally, NMR may prove useful for accurate chemo-typing of cannabis. In his interview with Analytical Cannabis, Harrington called NMR spectrometry an "information-rich method," which can "fingerprint" cannabis samples for analysis based on pattern recognition. If rolled out on a commercial scale, this ability to determine cultivar, region, and cannabinoid profile could revolutionize how the sector protects and patents the plant's many expressions.

NMR: The Next Generation of Cannabis Testing

NMR is already an established chemical analysis tool in other sectors, and the transition into cannabis makes both scientific and economic sense. It's faster, more cost-effective, and perhaps more accurate than the current approaches to cannabis testing. It may also amalgamate several complicated testing procedures into one single approach.

But NMR's ability to effectively chemotype cannabis is perhaps it's most exciting offering. There are already several companies working with NMR to offer this very service. Given more time, NMR may become the gold standard for cannabis fingerprinting.

 

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