The “Green Rush” of cannabis and hemp continues to increase because of the medicinal and health benefits of these two plants. The two major beneficial compound classes are the cannabinoids and terpenes. This article explores the various techniques for conducting analysis of these compounds, including: integrated versus modular high performance liquid chromatography (HPLC), HPLC versus ultrahigh-pressure liquid chromatography (UHPLC), UHPLC-ultraviolet (UV) versus UHPLC-photodiode array (PDA) detectors, HPLC-UV versus quadrupole liquid chromatography mass spectrometry (LC–MS) versus triple quadrupole mass spectrometry (LC–MS/MS), quadrupole time-of-flight mass spectrometers (QTOF-MS) versus matrix-assisted laser desorption or ionization time-of-flight mass spectrometers (MALDI-TOF-MS), LC versus gas chromatography (GC) systems, and sample preparation for LC- and GC-based methods.
The “Green Rush” of cannabis and hemp continues to increase because of the medicinal and health benefits of these two plants. The two major beneficial compound classes are the cannabinoids and terpenes. This article explores the various techniques for conducting analysis of these compounds.
Integrated Versus Modular HPLC
The most widely used technique for cannabinoid analysis is high performance liquid chromatography (HPLC). HPLC systems vary by many factors, such as capacity, versatility, and price. A lower-priced integrated HPLC would be a turnkey cannabis analyzer with an autosampler, pumps, columns, and detectors all built into an integrated housing. Turnkey packages provide all the tools necessary to analyze samples on day one, including the instrumentation, methods, standards, solvents, guard columns, analytical columns, and dedicated software with custom reporting templates. A modular HPLC system provides greater versatility because components can be interchanged as needed for many other applications.
HPLC Versus UHPLC
Once the decision has been made to purchase an integrated or modular HPLC system, the next decision is to choose between conventional HPLC and ultrahigh-pressure liquid chromatography (UHPLC); each has its own advantages and disadvantages. HPLC and UHPLC can both be obtained in integrated or modular formats.
Shown in Figure 1 is a chromatogram of 11 cannabinoids by HPLC in 10 min, while Figure 2 displays the UHPLC chromatogram of 17 cannabinoids in 5 min. Table I shows examples of the cannabinoids analyzed by HPLC and UHPLC. Armed with this information, the consumer may prefer the greater efficiency of separation from the UHPLC system. However, there are other factors that must be discussed.
HPLC is a more robust method. According to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH), “The robustness/ruggedness of an analytical procedure is a measure of its capacity to remain unaffected by small, but deliberate variations in method parameters and provides an indication of its reliability during normal usage” (1). Due to the robustness of HPLC, a lower-salaried technician could be utilized in place of a higher-salaried chemist for operation, sample preparation, and maintenance. Conversely, UHPLC demands the use of the highest quality solvents (UHPLC- or liquid chromatography–mass spectrometry [LC–MS]-grade) and that samples be filtered free of particulates.
In addition to robustness, the capital and operating costs for HPLC are lower. Instrument costs for HPLC systems are approximately 20% lower than for UHPLC systems. This takes into account the allowable use of HPLC-grade solvents instead of higher-cost UHPLC- or LC–MS-grade solvents. There is a lesser need to filter the mobile phase when using HPLC. A lower frequency of maintenance is another HPLC benefit, as a 30–50% reduction in the replacement of consumables, such as seals, plungers, rotors, and stators, can be realized.
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About the Authors
Bob Clifford, PhD, is the General Manager of Marketing at Shimadzu Scientific Instruments in Columbia, Maryland. Craig Young is the HPLC Product Manager at Shimadzu Scientific Instruments. Alan Owens is a Senior GCMS Product Specialist at Shimadzu Scientific Instruments. Jim Mott, PhD, is a Field Tech Support Supervisor at Shimadzu Scientific Instruments. Rachel Lieberman, PhD, is the Forensics Marketing Manager at Shimadzu Scientific Instruments. Direct correspondence to: [email protected].
How to Cite This Article
B. Clifford, C. Young, A. Owens, J. Mott, and R. Lieberman, Cannabis Science and Technology 3(1), 34-42 (2020).