Tag Archives: chemist

Spotlight on AOAC: New Leadership, New Initiatives In Cannabis & Food

By Aaron G. Biros
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AOAC INTERNATIONAL is an independent, third party, not-for-profit association and voluntary consensus standards developing organization. Founded in 1884, AOAC INTERNATIONAL was originally coined the Association of Official Agricultural Chemists. Later on, they changed their name to the Association of Official Analytical Chemists. Now that their members include microbiologists, food scientists as well as chemists, the organization officially changed its name to just AOAC INTERNATIONAL.

Much of AOAC’s work surrounds promoting food safety, food security and public health. Their work generally encompasses setting scientific standards for testing methodology, evaluating and adopting test methods and evaluating laboratory proficiency of test methods. The organization provides a forum for scientists to develop microbiological and chemical standards.

In December of 2018, they appointed Dr. Palmer Orlandi as deputy executive director and chief science officer. Dr. Orlandi has an extensive background at the U.S. Food and Drug Administration (FDA), serving the regulatory agency for more than 20 years. Most recently, he was the CSO and research director in the Office of Food and Veterinary Medicine at the FDA. He earned the rank of Rear Admiral and Assistant Surgeon General in 2017.

Dr. Palmer Orlandi is the new Deputy Executive Director and Chief Science Officer at AOAC.

Where It All Began With Cannabis

As recently as three years ago, AOAC began getting involved in the cannabis laboratory testing community, with a working group dedicated to developing standard method performance requirements for AOAC Official MethodsSM for cannabis testing. We sat down with Dr. Palmer Orlandi and a number of AOAC’s leaders to get an update on their progress working with cannabis testing as well as food security and food fraud.

According to Scott Coates, senior director of the AOAC Research Institute, they were approached three years ago to set up a working group for cannabis testing. “We created standards that we call the standard method performance requirements (SMPR®), which are detailed descriptions of what analytical methods should be able to do,” says Coates. “Using SMPRs, we issued a series of calls for methods and looked for methods that meet our standards. So far, we’ve completed four SMPRs- cannabinoids in plant material, cannabinoids in plant extracts, cannabinoids in chocolate (edibles), and one for pesticides in cannabis plant material.” AOAC doesn’t develop methods themselves, but they perform a comprehensive review of the methods and if they deem them acceptable, then the methods can be adopted and published in the AOAC compendium of methods, the Official Methods of Analysis of AOAC INTERNATIONAL.

Deborah McKenzie, senior director of Standards and Official Methods at AOAC

Deborah McKenzie, senior director of Standards and Official MethodsSM at AOAC, says the initial working group set the stage for really sinking their teeth into cannabis testing. “It started with methods for testing cannabinoids in plant dried material and plant extract,” says McKenzie. “That’s where our previous work has started to mold into the current effort we are launching.” McKenzie says they are looking forward to getting more involved with methods regarding chemical contaminants in cannabis, cannabinoids in various foods and consumables, as well as microbial organisms in cannabis. “We are pretty focused on testing labs having reliable and validated analytical solutions as our broad goal right now.”

Moving Forward, Expanding Their Programs

Coates says the work they’ve done over the past few years was more of a singular project, developed strictly for creating standards and to review methods. Now they are currently developing their Cannabis Analytical Science Program (CASP), which is expected to be an ongoing program. “We are looking to fully support the cannabis analytical community as best we can, which will potentially include working on reference materials, proficiency testing, education, training and ISO 17025 accreditation, all particularly as it applies to lab testing in the cannabis industry,” says Coates. “So, this CASP work is a much bigger and broader effort to cover more and to provide more support for labs doing the analysis of cannabis and its constituents, as well as hemp.”

According to Dr. Orlandi, they want this program to have a broad reach in the cannabis testing community. “As Scott pointed out, it’s not just strictly developing standards and methods,” says Dr. Orlandi. “It is going to be as all-encompassing as possible and will lead to training programs, a proficiency testing program and other areas.” Arlene Fox, senior director of AOAC’s Laboratory Proficiency Testing Program, says they are actively engaging in proficiency testing. “We are in the process of evaluating what is out there, what is possible and what’s needed as far as expanding proficiency testing for cannabis labs,” says Fox.

Regulatory Challenges & Obstacles

The obvious roadblock to much of AOAC’s work is that cannabis is still considered a controlled substance. “That creates some challenges for the work that we do in certain areas,” says Dr. Orlandi. “That is why this isn’t just a one-year project. We will work with these challenges and our stakeholders to address them.” AOAC had to put some limits on participation- for example, they had to decide that they cannot look for contributions or collaborations with producers and distributors, so long as cannabis is still a Schedule I controlled substance in the US.

Arlene Fox, senior director of AOAC’s Laboratory Proficiency Testing Program

Muddying the waters even further, the recent signing of the Farm Bill puts a clear distinction between most types of cannabis and industrial hemp. David Schmidt, executive director of AOAC realizes they need to be realistic with their stakeholders and in the eye of federal law.

While scientifically speaking, it’s pretty much the same plant just with slightly different chemical constituents, AOAC INTERNATIONAL has to draw a line in the sand somewhere. “As Palmer suggests, because of the Farm Bill being implemented and hemp being defined now as a legal substance from a controlled substance standpoint, industrial hemp has been given this exclusion,” says Schmidt. “So, we are trying to be realistic now, working with our stakeholders that work with hemp, trying to understand the reality of the federal law. We want to make clear that we can meet stakeholder needs and we want to distinguish hemp from cannabis to remain confident in the legality of it.” Schmidt says this is one of a number of topics they plan on addressing in detail at their upcoming 9thannual 2019 Midyear Meeting, held March 11-14 in Gaithersburg, Maryland.

Uniformity in Methodology: The Future of Cannabis Testing

Dr. Orlandi says his experience at the FDA has prepared him well for the work being done at AOAC. “The role that I served at the FDA prior to joining my colleagues here at AOAC was very similar: And that is to bring together stakeholders to accomplish or to solve a common problem.” Some of their stakeholders in the CASP program include BC Testing, Inc., the Association of Food and Drug Officials (AFDO), Bia Diagnostics, Bio-Rad, Industrial Laboratories, Materia Medica Labs, PerkinElmer, R-Biopharm AG, Supra R & D, TEQ Analytical Laboratories, Titan Analytical and Trilogy Analytical, among others.

David Schmidt, executive director of AOAC

“The underlying reason behind this effort is to create some level of harmonization for standards and methods,” says Dr. Orlandi. “They can be used in the near future to stay ahead of the curve for when regulatory agencies become involved. The idea is that these standards for analytical methods will already be established and as uniform as possible.”

When comparing cannabis to other industries in the US, Scott Coates mentions that most standards are signed off by the federal government. “When we started looking at pesticides in cannabis, it became really clear that we have a number of states doing things differently with different limits of quantification,” says Coates. “Each state, generally speaking, is setting their own standards. As Palmer was saying, one thing we are trying to do with this CASP program eventually will be to have some harmonization, instead of 30 different states having 30 different standards and methods.” So, on a much broader level, their goal for the CASP program is to develop a common set of standard methods, including hemp testing and even the Canadian market. “Hopefully this will be an international collaboration for standards for the methodology,” says Coates. They want to create a common set of standards, setting limits of quantification that will be accepted internationally, that will be accurate and repeatable and for the entire cannabis industry, not just state by state.

Food Authenticity & Fraud

One of the other activities that AOAC just launched recently is the food authenticity and fraud program. As the name implies, the goal is to start developing standards and methods and materials to look at economically adulterated foods, says Dr. Orlandi. That includes non-targeted analyses looking at matrices of food products that may be adulterated with an unknown target, as well as targeted analytes, identifying common adulterants in a variety of food products. “One example in the food industry is fraudulent olive oil,” says Dr. Orlandi. “Honey is another commodity that has experienced adulteration.” He says that in most cases these are economically motivated instances of fraud.

AOAC INTERNATIONAL is working in a large variety of other areas as well. All of these topics will be explored in much greater detail at their upcoming 9thannual 2019 Midyear Meeting, held March 11-14 in Gaithersburg, Maryland.

Pesticide Testing: Methods, Strategies & Sampling

By Charles Deibel
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Editor’s Note: The following is based on research and studies performed in their Santa Cruz Lab, with contributions from Mikhail Gadomski, Lab Manager, Ryan Maus, Technical Services Analyst, Dr. Laurie Post, Director of Food Safety & Compliance, Andy Sechler, Lab Director, Toby Astill, Senior Business Development Leader at Perkin Elmer and Charles Deibel, President of Deibel Cannabis Labs.


Pesticides represent the leading cause of batch failures in the cannabis industry. They are also the hardest tests to run in the laboratory, even one equipped with state-of-the-art equipment. The best instruments on the market are HPLC and GC dual mass spectrometer detectors, called “HPLC-qqq”, “GC-qqq,” or just triple quads.

As non-lab people, we envision a laboratory that can take a cannabis sample, inject it into a triple quad and have the machine quickly and effortlessly print out a report of pesticide values. Unfortunately, this is far from reality. The process is much more hands on and complex.In the current chemistry lab, trained analysts have to first program the triple quads to look for the pesticides of concern; in cannabis pesticide testing, this is done by programming the first of two mass spectrometers to identify a single (precursor) mass that is characteristic of the pesticide in question. For BCC requirements in California, this has to be done for all 66 pesticides, one at a time.

Next, these precursor ions are degraded into secondary chemicals called the “product” ions, also called transition ions. The second of the two mass spectrometers is used to analyze these transition ions. This process is graphed and the resulting spectrum is analyzed by trained chemists in the lab, pesticide by pesticide, for all the samples processed that day. If the lab analyzes 10 samples, that translates to 660 spectra to analyze (66 pesticides x 10 samples). When looking at the spectra for each pesticide, the analysts must compare the ratios of the precursor ions to the product ions.

Confirmation Testing

If these spectra indicate a given pesticide may be present, the chemists must then compare the ratios between the precursor and the products. If these ratios are not what is expected, then the analyst must perform confirmation testing to prove the precursor mass either is or is not the pesticide of concern. If the ratios are not what is expected, it means the molecule is similar to the pesticide in question, but may not be that pesticide. This confirmatory testing is key to producing accurate results and not failing batches when dealing with closely related chemicals. This process of analyzing spectra is done in all labs that are performing pesticide testing. In this fledgling industry, there are few published cannabis pesticide methods. 

The need for this type of confirmation testing doesn’t happen all of the time, but when it does, it will take longer than our targeted three-day turn-around time. In the picture above, one precursor mass is ionized into several product masses; but only two are large enough to be used for comparison. In this hypothetical situation, two product masses are produced for every one precursor, the expected ion abundance ratio should be less than 30%. When performing any confirmatory testing, if the ion abundance ratio is >30%, it means the original precursor molecule was not the pesticide of concern. For example, if the ion abundance ratio was 50%, then the original molecule broke down into too many parts; it was not the pesticide we were looking for. This ion abundance ratio threshold was established by FANCO, the international organization that sets guidelines for all pesticide testing.

Testing Strategies

Methodology: In this fledgling industry, there are few published cannabis pesticide methods. The identification of the precursor mass and product ions are not always published, leaving labs to research which ions should be used. This adds to the potential for differences between lab results. Once selected, labs should validate their research, through a series of experiments to ensure the correct precursor and transition (product) ions are being used in the method.

Sample Preparation: Beyond the time-consuming work that is required to develop sound pesticide methods, the extraction step is absolutely critical for credible results. If the pesticides aren’t fully extracted from the cannabis product, then the results will be lower than expected. Sample preparations are often not standardized between labs, so unless a given extraction technique is validated for accuracy, there is the possibility for differences between labs.

Getting a Representative Sample

The current California recommended amount of sample is one gram of product per batch. Batch sizes can vary greatly and it is entirely likely that two different one gram samples can have two different results for pesticides. Has the entire plant been evenly coated with exactly the same amount of pesticide onto every square inch of its leaves? No, probably not. That is why it is imperative to take a “random” sample, by taking several smaller samples from different areas of the entire batch.

Sampling Plans: We can learn a lot from the manufacturing and sampling best practices developed by the food industry through the years. If a food manufacturer is concerned with the possibility of having a bacteria pathogen, like Salmonella, in their finished product, they test the samples coming off their production lines at a statistically relevant level. This practice (theory) is called the sampling plan and it can easily be adapted to the cannabis industry. The basic premise is that the more you test, the higher your likelihood of catching a contaminate. Envision a rectangular swimming pool, but instead of water, it’s filled with jello. In this gelatinous small pool, 100 pennies are suspended at varying levels. The pennies represent the contaminates.

Is the pool homogenized? Is jello evenly represented in the entire pool? Yes. 

Is your concentrate evenly distributed in the extraction vessel? Yes. The question is, where are the pennies in that extraction vessel? The heavy metals, the microbial impurities and the pesticides should be evenly distributed in the extraction vessel but they may not be evenly represented in each sample that is collected. Unfortunately, this is the bane of the manufacturing industry and it’s the unfortunate reality in the food industry. If you take one random cup of jello, will you find the penny? Probably not. But it you take numerous 1 cup samples from random areas within the batch, you increase your chances of finding the contaminate. This is the best approach for sampling any cannabis product.

The best way to approve a batch of cannabis product is to take several random samples and composite them. But you may need to run several samples from this composite to truly understand what is in the batch. In the swimming pool example, if you take one teaspoon scoop, will you find one of the pennies? The best way to find one of the pennies is to take numerous random samples, composite them and increase the number of tests you perform at the lab. This should be done on any new vendor/cultivator you work with, in order to help establish the safety of the product.

IR Spectrum of 2,4-Dichlorophenol in different physical states
From The Lab

Gas Chromatography/Infrared Spectroscopy: A Tool For the Analysis of Organic Compounds in Cannabis

By John F. Schneider
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IR Spectrum of 2,4-Dichlorophenol in different physical states

Editor’s Note: The author will be teaching a 1/2 day short course on this topic at PITTCON in Philadelphia in March 2019.


The combination of gas chromatography and infrared spectroscopy (GC/IR) is a powerful tool for the characterization of compounds in complex mixtures. (1-5) Gas chromatography with mass spectroscopy detection (GC/MS) is a similar technique, but GC/MS is a destructive technique that tears apart the sample molecules during the ionization process and then these fragments are used to characterize the molecule. In GC/IR the molecules are not destroyed but the IR light produced by molecular vibrations are used to characterize the molecule. IR spectrum yields information about the whole molecule which allows the characterization of specific isomers and functional groups. GC/IR is complementary to GC/MS and the combination results in a powerful tool for the analytical chemist.

A good example of the utility of GC/IR vs GC/MS is the characterization of stereo isomers. Stereo isomers are mirror images such as a left hand and a right hand. In nature, stereo isomers are very important as one isomers will be more active then its mirror image. Stereo isomers are critical to medicinal application of cannabis and also a factor in the flavor components of cannabis.

GC/MS is good at identifying basic structure, where GC/IR can identify subtle differences in structure. GC/MS could identify a hand, GC/IR could tell you if it is a left hand or right hand. GC/MS can identify a general class of compounds, GC/IR can identify the specific isomer present.

Why GC/IR?

Gas chromatography interfaced with infrared detection (GC/IR), combines the separation ability of GC and the structural information from IR spectroscopy. GC/IR gives the analyst the ability to obtain information complementary to GC/MS. GC/IR gives the analyst the power to perform functional group detection and differentiate between similar molecular isomers that is difficult with GC/MS. Isomer specificity can be very important in flavor and medical applications.

 IR Spectrum of 2,4-Dichlorophenol in different physical states

IR Spectrum of 2,4-Dichlorophenol in different physical states

Gas chromatography with mass spectrometry detection (GC/MS) is the state-of-the-art method for the identification of unknown compounds. GC/MS, however, is not infallible and many compounds are difficult to identify with 100 % certainty. The problem with GC/MS is that it is a destructive method that tears apart a molecule. In infrared spectrometry (IR), molecular identification is based upon the IR absorptions of the whole molecule. This technique allows differentiation among isomers and yields information about functional groups and the position of such groups in a molecule. GC/IR complements the information obtained by GC/MS.

Interfaces

Initial attempts to couple GC with IR were made using high capacity GC columns and stopped flow techniques. As GC columns and IR technology advanced, the GC/IR method became more applicable. The advent of fused silica capillary GC columns and the availability of Fourier transform infrared spectrometry made GC/IR available commercially in several forms. GC/IR using a flow cell to capture the IR spectrum in real time is known as the “Light Pipe”. This is the most common form of GC/IR and the easiest to use. GC/IR can also be done by capturing or “trapping” the analytes of interest eluting from a GC and then measuring the IR spectrum. This can be done by cryogenically trapping the analyte in the solid phase. A third possibility is to trap the analyte in a matrix of inert material causing “Matrix Isolation” of the analyte followed by measuring the IR spectrum.

Infrared Spectroscopy

The physical state of the sample has a large effect upon the IR spectrum produced. Molecular interactions (especially hydrogen bonding) broadens absorption peaks. Solid and liquid samples produce IR spectra with broadened peaks that loses much of the potential information obtained in the spectra. Surrounding the sample molecule with gas molecules or in an inert matrix greatly sharpens the peaks in the spectrum, revealing more of the information and producing a “cleaner” spectrum. These spectra lend themselves better to computer searches of spectral libraries similar to the computer searching done in mass spectroscopy. IR spectral computer searching requires the standard spectra in the library be of the same physical state as the sample. So, a spectrum taken in a gaseous state should be searched against a library of spectra of standards in the gaseous state.

IR of various phases:

  • Liquid Phase – Molecular interactions broaden absorption peaks.
  • Solid Phase – Molecular interactions broaden absorption peaks.
  • Gas Phase – Lack of molecular interactions sharpen absorption peaks.
  • Matrix Isolation – Lack of molecular interactions sharpen absorption peaks.

IR Chromatograms

GC/IR yields chromatograms of infrared absorbance over time. These can be total infrared absorbance which is similar to the total ion chromatogram (TIC) in GC/MS or the infrared absorbance over a narrow band or bands analogous to selected ion chromatogram. This is a very powerful ability, because it gives the user the ability to focus on selected functional groups in a mixture of compounds.

Conclusion

Gas chromatography with infrared detection is a powerful tool for the elucidation of the structure of organic compounds in a mixture. It is complementary to GC/MS and is used to identify specific isomers and congeners of organic compounds. This method is greatly needed in the Cannabis industry to monitor the compounds that determine the flavor and the medicinal value of its products.


References

  1. GC–MS and GC–IR Analyses of the Methoxy-1-n-pentyl-3-(1-naphthoyl)-Indoles: Regioisomeric Designer Cannabinoids, Amber Thaxton-Weissenfluh, Tarek S. Belal, Jack DeRuiter, Forrest Smith, Younis Abiedalla, Logan Neel, Karim M. Abdel-Hay, and C. Randall Clark, Journal of Chromatographic Science, 56: 779-788, 2018
  2. Simultaneous Orthogonal Drug Detection Using Fully Integrated Gas Chromatography with Fourier Transform Infrared Detection and Mass Spectrometric Detection , Adam Lanzarotta, Travis Falconer, Heather McCauley, Lisa Lorenz, Douglas Albright, John Crowe, and JaCinta Batson, Applied Spectroscopy Vol. 71, 5, pp. 1050-1059, 2017
  3. High Resolution Gas Chromatography/Matrix Isolation Infrared Spectrometry, Gerald T. Reedy, Deon G. Ettinger, John F. Schneider, and Sid Bourne, Analytical Chemistry, 57: 1602-1609, 1985
  4. GC/Matrix Isolation/FTIR Applications: Analysis of PCBs, John F. Schneider, Gerald T. Reedy, and Deon G. Ettinger, Journal of Chromatographic Science, 23: 49-53, 1985
  5. A Comparison of GC/IR Interfaces: The Light Pipe Vs. Matrix Isolation, John F. Schneider, Jack C. Demirgian, and Joseph C. Stickler, Journal of Chromatographic Science, 24: 330- 335, 1986
  6. Gas Chromatography/Infrared Spectroscopy, Jean ‐ Luc Le Qu é r é , Encyclopedia of Analytical Chemistry, John Wiley & Sons, 2006

Ask the Expert: Q&A with Steve Stadlmann on Cannabis lab Accreditation

By Aaron G. Biros
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Steve Stadlmann has an extensive background as an analytical chemist working in laboratories since the early 90’s. He is now a sales specialist at PerkinElmer, an analytical instrument manufacturer that provides instruments for cannabis testing labs, in addition to a host of other industries. With over two decades of experience working in environmental testing labs, food and beverage labs and agricultural testing labs, Stadlmann is extremely familiar with the instruments used in cannabis labs.

Steve Stadlmann, sales specialist at Perkin Elmer

In 2014, he started working in the cannabis space with TriQ, Inc., a technology solutions provider for cannabis growers, where he worked in product development on a line of nutrients. In April of 2016, he started working at Juniper Analytics, a cannabis-testing laboratory in Bend, Oregon. As laboratory director there, he created their quality manual, quality assurance plan, SOP’s and all the technical documentation for ORELAP accreditation. He developed new methodologies for cannabis testing industry for residual solvents, terpene profiles and potency analysis. He worked with PerkinElmer on pesticide methodology for the QSight™ Triple Quadrupole LC/MS/MS system and implemented operational procedures and methods for LC-UV, GCMS and LC-MS/MS, including sample prep for cannabis products.

He left Juniper Analytics about two months ago to work with PerkinElmer as a sales specialist. With extensive experience in helping get Juniper’s lab accredited, he is a wealth of knowledge on all things cannabis laboratory accreditation. PerkinElmer will be hosting a free webinar on September 12th that takes a deep dive into all things cannabis lab accreditation. Ahead of the upcoming webinar, Getting Accreditation in the Cannabis Industry, we sit down with Stadlmann to hear his observations on what instruments he recommends for accreditation, and processes and procedures to support that. Take a look at our conversation below to get a glimpse into what this webinar will discuss.

CannabisIndustryJournal: How can cannabis labs prepare for accreditation with selecting instrumentation?

Steve: Finding the appropriate instrumentation for the regulations is crucial. Ensuring the instrumentation not only has the capabilities of analyzing all the required compounds, but also able to achieve appropriate detection limit requirements. In addition, having an instrument manufacturer as a partner, that is willing and able to assist in method development, implementation and continued changes to the testing requirements at the state level (and potentially national level) is key.

Another consideration is robustness of the equipment. The instrumentation must be capable of high throughput for fast turnaround times of results. Unlike the environmental industry, the cannabis industry has consumer products with expiration dates. Clients demand quick turnaround of results to get product to market as quickly as possible and avoid sitting on inventory for any length of time.

To add to the robustness need, sample matrices in the cannabis industry can be quite challenging in relation to analytical instrumentation. Equipment that is able to handle these matrices with minimal downtime for routine service is becoming a requirement to maintain throughput needs of the industry.

CIJ: What are the most crucial procedures and practices for achieving ISO 17025 accreditation?

Steve: Development and documentation of processes and procedures following Good Laboratory Practices and procedures is essential to a successful accreditation process. Great attention must be paid to the quality objectives of the laboratory as well as associated documentation, including tracking of any errors, deviations, updates, complaints, etc.

Data integrity is a key component to any accrediting body and includes implementation and/or development of appropriate methods with support data proving acceptable results. In addition, documentation of all procedures and processes along with tracking of all steps in the process during routine laboratory work should be a priority. The ability to show a complete, documented trail of all procedures done to any sample is important in ensuring the results can be reproduced and ensuring no deviations occurred, in turn potentially causing questionable results.

Last but not least: training. Laboratory staff should be well versed in any procedures they are involved in to ensure high data quality and integrity. If any laboratory staff does not receive appropriate training in any operating procedures, the data quality becomes suspect.

CIJ: What are some of the biggest obstacles or pitfalls cannabis labs face when trying to get accredited?

Steve: Not fully preparing to meet any agency and testing regulations and requirements will cause delays in the accreditation process and potentially more work for the laboratory. From documentation to daily operations, if any aspect becomes a major finding for an auditor, additional data is usually required to prove the error has been fixed satisfactorily.

Taking the time early on to ensure all documentation, processes and procedures are adhering to any regulatory agency requirements is important for a smooth accreditation process. It is easy to overlook small details when building out the operating procedures that might be essential in the process. Again, going back to data quality, the laboratory must ensure all steps are outlined and documented to ensure high quality (reproducible) data and integrity.

A new employee should be able to come in and read a quality manual and standard operating procedure and produce equivalent data to any laboratory analyst doing the same job. With difficult or challenging operating procedures it becomes even more important that training and documentation are adhered to.


PerkinElmer’s free webinar will dive into these points and others in more detail. To learn more and sign up, click here.

The Practical Chemist

Potency Analysis of Cannabis and Derivative Products: Part 2

By Rebecca Stevens
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As mentioned in Part 1, the physiological effects of cannabis are mediated by a group of structurally related organic compounds known as cannabinoids. The cannabinoids are biosynthetically produced by a growing cannabis plant and Figure 1 details the biosynthetic pathways leading to some of the most important cannabinoids in plant material.

Potency figure 1
Figure 1: The biosynthetic pathway of phytocannabinoid production in cannabis has been deeply studied through isotopic labeling experiments

The analytical measurement of cannabinoids is important to ensure the safety and quality of cannabis as well as its extracts and edible formulations. Total cannabinoid levels can vary significantly between different cultivars and batches, from about 5% up to 20% or more by dry weight. Information on cannabinoid profiles can be used to tailor cultivars for specific effects and allows end users to select an appropriate dose.

Routine Analysis vs. Cannabinomics 

Several structurally analogous groups of cannabinoids exist. In total, structures have been assigned for more than 70 unique phytocannabinoids as of 2005 and the burgeoning field of cannabinomics seeks to comprehensively measure these compounds.¹

Considering practical potency analysis, the vast majority of cannabinoid content is accounted for by 10-12 compounds. These include Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabigerol (CBG), Δ9-tetrahydrocannabivarian (THCV), cannabidivarin (CBDV) and their respective carboxylic acid forms. The cannabinoids occur primarily as carboxylic acids in plant material. Decarboxylation occurs when heat is applied through smoking, vaporization or cooking thereby producing neutral cannabinoids which are more physiologically active.

Potency Analysis by HPLC and GC

Currently, HPLC and GC are the two most commonly used techniques for potency analysis. In the case of GC, the heat used to vaporize the injected sample causes decarboxylation of the native cannabinoid acids. Derivatization of the acids may help reduce decarboxylation but overall this adds another layer of complexity to the analysis² ³. HPLC is the method of choice for direct analysis of cannabinoid profiles and this technique will be discussed further.

A sample preparation method consisting of grinding/homogenization and alcohol extraction is commonly used for cannabis flower and extracts. It has been shown to provide good recovery and precision² ³. An aliquot of the resulting extract can then be diluted with an HPLC compatible solvent such as 25% water / 75% acetonitrile with 0.1% formic acid. The cannabinoids are not particularly water soluble and can precipitate if the aqueous percentage is too high.

To avoid peak distortion and shifting retention times the diluent and initial mobile phase composition should be reasonably well matched. Another approach is to make a smaller injection (1-2 µL) of a more dissimilar solvent. The addition of formic acid or ammonium formate buffer acidifies the mobile phase and keeps the cannabinoid acids protonated.

The protonated acids are neutral and thus well retained on a C18 type column, even at higher (~50% or greater) concentrations of organic solvent² ³.

Detection is most often done using UV absorbance. Two main types of UV detectors are available for HPLC, single wavelength and diode array. A diode array detector (DAD) measures absorbance across a range of wavelengths producing a spectrum at each point in a chromatogram while single wavelength detectors only monitor absorbance at a single user selected wavelength. The DAD is more expensive, but very useful for detecting coelutions and interferences.

References

  1. Chemical Constituents of Marijuana: The Complex Mixture of Natural Cannabinoids. Life Sciences, 78, (2005), pp. 539
  2. Development and Validation of a Reliable and Robust Method for the Analysis of Cannabinoids and Terpenes in Cannabis. Journal of AOAC International, 98, (2015), pp. 1503
  3. Innovative Development and Validation of an HPLC/DAD Method for the Qualitative and Quantitative Determination of Major Cannabinoids in Cannabis Plant Material. Journal of Chromatography B, 877, (2009), pp. 4115

Rebecca is an Applications Scientist at Restek Corporation and is eager to field any questions or comments on cannabis analysis, she can be reached by e-mail, rebecca.stevens@restek.com or by phone at 814-353-1300 (ext. 2154)

amandarigdon
The Practical Chemist

Easy Ways to Generate Scientifically Sound Data

By Amanda Rigdon
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amandarigdon

I have been working with the chemical analysis side of the cannabis industry for about six years, and I have seen tremendous scientific growth on the part of cannabis labs over that time. Based on conversations with labs and the presentations and forums held at cannabis analytical conferences, I have seen the cannabis analytical industry move from asking, “how do we do this analysis?” to asking “how do we do this analysis right?” This change of focus represents a milestone in the cannabis industry; it means the industry is growing up. Growing up is not always easy, and that is being reflected now in a new focus on understanding and addressing key issues such as pesticides in cannabis products, and asking important questions about how regulation of cannabis labs will occur.

While sometimes painful, growth is always good. To support this evolution, we are now focusing on the contribution that laboratories make to the safety of the cannabis consumer through the generation of quality data. Much of this focus has been on ensuring scientifically sound data through regulation. But Restek is neither a regulatory nor an accrediting body. Restek is dedicated to helping analytical chemists in all industries and regulatory environments produce scientifically sound data through education, technical support and expert advice regarding instrumentation and supplies. I have the privilege of supporting the cannabis analytical testing industry with this goal in mind, which is why I decided to write a regular column detailing simple ways analytical laboratories can improve the quality of their chromatographic data right now, in ways that are easy to implement and are cost effective.

Anyone with an instrument can perform chromatographic analysis and generate data. Even though results are generated, these results may not be valid. At the cannabis industry’s current state, no burden of proof is placed on the analytical laboratory regarding the validity of its results, and there are few gatekeepers between those results and the consumer who is making decisions based on them. Even though some chromatographic instruments are super fancy and expensive, the fact is that every chromatographic instrument – regardless of whether it costs ten thousand or a million dollars – is designed to spit out a number. It is up to the chemist to ensure that number is valid.

In the first couple of paragraphs of this article, I used terms to describe ‘good’ data like ‘scientifically-sound’ or ‘quality’, but at the end of the day, the definition of ‘good’ data is valid data. If you take the literal meaning, valid data is justifiable, logically correct data. Many of the laboratories I have had the pleasure of working with over the years are genuinely dedicated to the production of valid results, but they also need to minimize costs in order to remain competitive. The good news is that laboratories can generate valid scientific results without breaking the bank.

In each of my future articles, I will focus on one aspect of valid data generation, such as calibration and internal standards, explore it in practical detail and go over how that aspect can be applied to common cannabis analyses. The techniques I will be writing about are applied in many other industries, both regulated and non-regulated, so regardless of where the regulations in your state end up, you can already have a head start on the analytical portion of compliance. That means you have more time to focus on the inevitable paperwork portion of regulatory compliance – lucky you! Stay tuned for my next column on instrument calibration, which is the foundation for producing quality data. I think it will be the start of a really good series and I am looking forward to writing it.