Tag Archives: MS

Analytical Instruments You Need to Start a Cannabis Testing Laboratory

By Bob Clifford
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The cannabis industry is growing exponentially, and the use of cannabis for medical purposes is being adopted across the nation. With this boom in cannabis consumers, there has been an increasing need for knowledge about the product.

The role of testing labs has become crucial to the process, which makes owning and operating a lab more lucrative. Scientists testing for potency, heavy metals, pesticides, residual solvents, moisture, terpene profile, microbial and fungal growth, and mycotoxins/aflatoxins are able to make meaningful contributions to the medical industry by making sure products are safe, while simultaneously generating profits and a return on investment.

Here are the key testing instruments you need to conduct these critical analyses. Note that cannabis analytical testing requirements may vary by state, so be sure to check the regulations applicable to the location of your laboratory.

Potency Testing

High-performance liquid chromatograph (HPLC) designed for quantitative determination of cannabinoid content.

The most important component of cannabis testing is the analysis of cannabinoid profiles, also known as potency. Cannabis plants naturally produce cannabinoids that determine the overall effect and strength of the cultivar, which is also referred to as the strain. There are many different cannabinoids that all have distinct medicinal effects. However, most states only require testing and reporting for the dry weight percentages of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). It should be noted that delta-9-tetrahydrocannabinolic acid (Δ9-THCA) can be converted to THC through oxidation with heat or light.

For potency testing, traditional high-performance liquid chromatography (HPLC) is recommended and has become the gold standard for analyzing cannabinoid profiles. Look for a turnkey HPLC analyzer that delivers a comprehensive package that integrates instrument hardware, software, consumables and proven HPLC methods.

Heavy Metal Testing

ICP-MS instrument for detecting heavy metals in cannabis.

Different types of metals can be found in soils and fertilizers, and as cannabis plants grow, they tend to draw in these metals from the soil. Heavy metals are a group of metals considered to be toxic, and the most common include lead, cadmium, arsenic and mercury. Most labs are required to test and confirm that samples are under the allowable toxic concentration limits for these four hazardous metals.

Heavy metal testing is performed by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS uses the different masses of each element to determine which elements are present within a sample and at what concentrations. Make sure to include accompanying software that provides assistant functions to simplify analysis by developing analytical methods and automatically diagnosing spectral interference. This will provide easy operation and analytical results with exceptionally high reliability.

To reduce running costs, look for a supporting hardware system that reduces the consumption of argon gas and electricity. For example, use a plasma ignition sequence that is optimized for lower-purity argon gas (i.e., 99.9% argon as opposed to more expensive 99.9999%).

Pesticide Testing

The detection of pesticides in cannabis can be a challenge. There are many pesticides that are used in commercial cannabis grow operations to kill the pests that thrive on the plants and in greenhouses. These chemicals are toxic to humans, so confirming their absence from cannabis products is crucial. The number of pesticides that must be tested for varies from state to state, with Colorado requiring only 13 pesticides, whereas Oregon and California require 59 and 66 respectively. Canada has taken it a step further and must test for 96 pesticides, while AOAC International is developing methods for testing for 104 pesticides. The list of pesticides will continue to evolve as the industry evolves.

Testing for pesticides is one of the more problematic analyses, possibly resulting in the need for two different instruments depending on the state’s requirements. For a majority of pesticides, liquid chromatography mass spectrometry (LCMS) is acceptable and operates much like HPLC but utilizes a different detector and sample preparation.

With excellent sensitivity and ultra-low detection limits, LC-MS/MS is an ideal technique for the analysis of pesticides.

Pesticides that do not ionize well in an LCMS source require the use of a gas chromatography mass spectrometry (GCMS) instrument. The principles of HPLC still apply – you inject a sample, separate it on a column and detect with a detector. However, in this case, a gas (typically helium) is used to carry the sample.

Look for a LC-MS/MS system or HPLC system with a triple quadrupole mass spectrometer that provides ultra-low detection limits, high sensitivity and efficient throughput. Advanced systems can analyze more than 200 pesticides in 12 minutes.

For GCMS analysis, consider an instrument that utilizes a triple quadrupole mass spectrometer to help maximize the capabilities of your laboratory. Select an instrument that is designed with enhanced functionality, analysis software, databases and a sample introduction system. Also include a headspace autosampler, which can also be used for terpene profiles and residual solvent testing.

Residual Solvent Testing

Residual solvents are chemicals left over from the process of extracting cannabinoids and terpenes from the cannabis plant. Common solvents for such extractions include ethanol, butane, propane and hexane. These solvents are evaporated to prepare high-concentration oils and waxes. However, it is sometimes necessary to use large quantities of solvent in order to increase extraction efficiency and to achieve higher levels of purity. Since these solvents are not safe for human consumption, most states require labs to verify that all traces of the substances have been removed.

Testing for residual solvents requires gas chromatography (GC). For this process, a small amount of extract is put into a vial and heated to mimic the natural evaporation process. The amount of solvent that is evaporated from the sample and into the air is referred to as the “headspace.” The headspace is then extracted with a syringe and placed in the injection port of the GC. This technique is called full-evaporated technique (FET) and utilizes the headspace autosampler for the GC.

Look for a GCMS instrument with a headspace autosampler, which can also be used for pesticide and terpene analysis.

Terpene Profile Testing

Terpenes are produced in the trichomes of the cannabis leaves, where THC is created, and are common constituents of the plant’s distinctive flavor and aroma. Terpenes also act as essential medicinal hydrocarbon building blocks, influencing the overall homeopathic and therapeutic effect of the product. The characterization of terpenes and their synergistic effect with cannabinoids are key for identifying the correct cannabis treatment plan for patients with pain, anxiety, epilepsy, depression, cancer and other illnesses. This test is not required by most states, but it is recommended.

The instrumentation that is used for analyzing terpene profiles is a GCMS with headspace autosampler with an appropriate spectral library. Since residual solvent testing is an analysis required by most states, all of the instrumentation required for terpene profiling will already be in your lab.

As with residual solvent testing, look for a GCMS instrument with a headspace autosampler (see above). 

Microbe, Fungus and Mycotoxin Testing

Most states mandate that cannabis testing labs analyze samples for any fungal or microbial growth resulting from production or handling, as well as for mycotoxins, which are toxins produced by fungi. With the potential to become lethal, continuous exposure to mycotoxins can lead to a buildup of progressively worse allergic reactions.

LCMS should be used to qualify and identify strains of mycotoxins. However, determining the amount of microorganisms present is another challenge. That testing can be done using enzyme linked immunosorbent assay (ELISA), quantitative polymerase chain reaction (qPCR) or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), with each having their advantages and disadvantages.

For mycotoxin analysis, select a high-sensitivity LC-MS/MS instrument. In addition to standard LC, using an MS/MS selective detector enables labs to obtain limits of detection up to 1000 times greater than conventional LC-UV instruments.

For qPCR and its associated needs, look for a real-time PCR amplification system that combines thermal cyclers with optical reaction modules for singleplex and multiplex detection of fluorophores. These real-time PCR detection systems range from economical two-target detection to sophisticated five-target or more detection systems. The real-time detection platform should offer reliable gradient-enabled thermal cyclers for rapid assay optimization. Accompanying software built to work with the system simplifies plate setup, data collection, data analysis and data visualization of real-time PCR results.

Moisture Content and Water Activity Testing

Moisture content testing is required in some states. Moisture can be extremely detrimental to the quality of stored cannabis products. Dried cannabis typically has a moisture content of 5% to 12%. A moisture content above 12% in dried cannabis is prone to fungal growth (mold). As medical users may be immune deficient and vulnerable to the effects of mold, constant monitoring of moisture is needed. Below a 5% moisture content, the cannabis will turn to a dust-like texture.

The best way to analyze the moisture content of any product is using the thermogravimetric method with a moisture balance instrument. This process involves placing the sample of cannabis into the sample chamber and taking an initial reading. Then the moisture balance instrument heats up until all the moisture has been evaporated out of the sample. A final reading is then taken to determine the percent weight of moisture that was contained in the original sample.

A moisture balance can provide accurate determination of moisture content in cannabis.

Look for a moisture balance that offers intuitive operation and quick, accurate determination of moisture content. The pan should be spacious enough to allow large samples to be spread thinly. The halogen heater and reflector plate should combine to enable precise, uniform heating. Advanced features can include preset, modifiable measurement modes like automated ending, timed ending, rapid drying, slow drying and step drying.

Another method for preventing mold is monitoring water activity (aW). Very simply, moisture content is the total amount of water available, while water activity is the “free water” that could produce mold. Water activityranges from 0 to 1. Pure water would have an aW of 1.0. ASTM methods D8196-18 and D8297-18 are methods for monitoring water activity in dry cannabis flower. The aW range recommended for storage is 0.55 to 0.65. Some states recommend moisture content to be monitored, other states monitor water activity, and some states such as California recommend monitoring both.

Final Thoughts

As you can see, cannabis growers benefit tremendously from cannabis testing. Whether meeting state requirements or certifying a product, laboratory testing reduces growers’ risk and ensures delivery of a quality product. As medicinal and recreational cannabis markets continue to grow, analytical testing will ensure that consumers are receiving accurately

labeled products that are free from contamination. That’s why it is important to invest in the future of your cannabis testing lab by selecting the right analytical equipment at the start of your venture.

UKflag

How Much Cannabis Astroturfing Is Afoot In The UK?

By Marguerite Arnold
1 Comment
UKflag

Astroturfing is the practice, in political messaging and campaigns, of creating what seems to be a legitimate, grassroots inspired campaign that is actually bought and paid for by an industry lobby or other corporate interests.

It is also clear that this practice is now entering the cannabis space, certainly in the UK.

How and Where?

On August 1, the British Conservative Drug Policy Reform Group sent out a group email entitled “Strategic litigation on medical cannabis access in the UK.” The email, from the group’s senior communications manager, was to announce the kick-off of a crowdfunding campaign to defend a cannabis patient.

It’s beneficiary? A British female MS patient, Lezley Gibson, now facing prosecution for growing her own cannabis after being unable to afford what was on offer at her local pharmacy.

Here is the first flag: MS is the only condition for which Sativex (manufactured by British firm GW Pharma) is prescribed on label (in other words without special approvals).

The problem is that the NHS (along with most of the German statutory approvers) feels that Sativex is still too expensive and not effective enough. And that problem won’t be solved with either patient home grow access or a lawsuit to gain that right, but rather funded trials.

UKflagHowever, more disturbingly, the email referenced the supposed success of a similar legal tactic in Germany several years ago. This is to say it used a highly inaccurate analogy. In Germany, a male chronic pain patient sued the government for the right to grow his own cannabis. He won the right temporarily, but this was taken away from him after the law changed in March 2017. Now he, like every other cannabis patient in Germany, must get his cannabis from a pharmacy. German patients also must get their initial prescription approved by health insurers – which is for everyone – but particularly non MS patients – the biggest fight in the room right now on the topic of medical efficacy.

Further, the right to grow one’s own medical cannabis, no matter the condition suffered, has been removed from patients in every legal jurisdiction where there is no constitutional right to it first – namely patients sue for the same.

As such, it is entirely conceivable that as a “strategic” case, this is more likely to put pressure on the NHS to pay the sky-high price of Sativex for MS patients (which it has already refused to do) than create any other kind of access for anyone else.

When contacted by Cannabis Industry Journal, a CDPRG spokesperson said that the patient had given her support for the crowdfunding campaign and needed help.

piechart
Most German Patients Are Still Only Getting Dronabinol

However, there are other issues here. Namely that when selecting a strategic case (no matter how harsh this sounds to the individual patient), the entire discussion at this point – certainly from an efficacy point of view, might be better served with supporting the case of a patient who has less access because of either physical condition or economic status.

In fact, in Germany so far, thanks to the change in the law that the British group references, while there certainly are tens of thousands of cannabis patients at the moment (including many MS patients), the majority of them receive Dronabinol or Sativex. And all of them have to fight for medical access and approval from their insurers. That is of course, when they can find a doctor to prescribe in the first place. There are also estimates that there are close to a million patients in Germany who cannot get access, thanks to the change in the law created by one patient’s law suit.

Is this flavour of litigatious advocacy now afoot in the UK, in other words, the kind of lawsuit that is designed to benefit the industry more than patients looking for affordable, home-grown, if regulated product?

Astroturfing Cannabis Issues Under Brexit Colors?

No matter the real versus stated intent of the instigators of the Gibson case, or the eventual outcome of such litigation, there is no doubt that cannabis is being brought into larger political debates. And further, no surprise, “patient access” is an issue just as ripe for “issue manipulation” and astroturfing as anything else.

“Strategic” if not “crowdfunded” cause or tactical lawsuits are another form of this technique.

That foreign cannabis money is already in the room is also no surprise. The British press was alight with stories during June of the amount of money contributed to the CDPR Group from Canadian sources.

Seen within the context of Brexit itself, this is disturbing locally.There are other issues involved in this kind of challenge to the law.

Not to mention the fact that in May, none other than Arron Banks, the self-styled backer of the Leave Campaign, decided, suddenly, to throw his hat into the CBD oil ring on Twitter. Not to mention repeated the same information repeatedly, including his $4 million investment into the space during the following months so far. Plus, of course, wildly optimistic valuations of the U.S. market.

Suing For Patient Justice Or A Backdoor For Canadian and Other Corporate Interests?

There are other issues involved in this kind of challenge to the law.

The first is that in the British case this is actually not a constitutional case per se, but a human rights one. See the problems that those who are trying to define the British constitution right now on other matters (see Brexit) are running into.

The second is that while the patient in question in this case (Ms. Gibson) is undoubtedly relieved at the prospect of a legal defence for growing her own medication in the face of insurmountable cost, on the “positive” side, her case is unlikely to do much more than make impoverished patients fight NHS paperwork if they can find a doctor. See Germany, as a prime example.This lawsuit, in other words, no matter how it might get one woman out of a terrible legal situation, is not necessarily “pro-patient.”

But what it will do is something else. It may well remove the current widespread prohibition on the harvesting of cannabis flower in the UK. And while patients would face again being moved into the slow lane of NHS approvals (with lots of fights over efficacy looming and still unsolved), corporate growers and processors if not importers, already investing millions into such efforts across the UK and Ireland, benefit.

At the exclusion, also, as has been the case in Germany, of local producers who are not already large corporate interests or existing farms.

This lawsuit, in other words, no matter how it might get one woman out of a terrible legal situation, is not necessarily “pro-patient.” It also may well do everything to frustrate, slow down and further complicate medical access for those at the end of the chain, while only opening up “investment opportunities” for large companies and well-heeled interests who have nothing but profit, if not the destruction of the NHS in mind.

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
2 Comments
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
Terpene_KAS2
From The Lab

The Other Side of Cannabis: Terpenes

By Dr. Zacariah Hildenbrand, Allegra Leghissa, Dr. Kevin A. Schug
2 Comments
Terpene_KAS2

Have you ever wondered why all beers have that strong, characteristic smell? Or why you could tell the smell of cannabis apart from any other plant? The answer is simple – terpenes.

These 55,000 different molecules are responsible for a majority of the odors and fragrances around us, from a pine forest, to the air diffuser in your house 1–3. They all share the same precursor, isoprene, and because of that, they are all related and have similar molecular structures. Unfortunately, it is this uncanny similarity that makes their analysis so challenging; we still lack a complete list of which terpenes expected to be found in each given plant species 1,2.

Many different methods have been developed in an effort to provide a time-optimized and straightforward analysis. Gas chromatography (GC) is usually center stage due to the volatility of the terpenes. Therefore, there is significant concern with the type of GC detector used 2.

The flame ionization detector (FID) is a good quantitative detector for GC, but qualitatively it does not provide any information, except for retention time; the differentiation between terpene species is achieved solely by use of retention indices (RI), which are based on elution times from a particular GC stationary phase. The best part of the FID is its low cost, reliability, and relatively easy interface, which make it an effective tool for quality control (QC) but less so with respect to research and discovery 2.

The primary choice for a research setting is the mass spectrometer (MS) detector. It is more expensive and complicated than FID, but importantly, it provides both good quantitative capabilities, and it provides mass spectra for each species that elutes from the chromatograph. However, for terpene analysis, it may still not be the best detector choice. Since terpene class molecules share many structural and functional similarities, even their fragmentation and sub-sequential identification by MS may lead to inconsistent results, which need to be confirmed by use of RI. Still, MS is a better qualitative analysis tool than the FID, especially for distinguishing non-isobaric terpenes 2.

Recently, new technology based on vacuum ultraviolet spectroscopy (VUV) has been developed as a new GC detector. The VUV detector enables analysis of virtually all molecules; virtually all chemical compounds absorb light in the range in the 125-240 nm wavelength range probed by the detector, making it an essentially universal detector 4–11. Previously, spectroscopic absorption detectors for GC have lacked sufficient energy to measure absorption of most GC-amenable species. The VUV detector fills a niche, which is complementary to MS detection in terms of the qualitative information it provides.

Terpene_KAS2
Figure 1: A, Section of the chromatographic separation of a terpenes standard mix; B, highlight of the co-eluting terpenes, camphor and (-)-isopulegol; C, differences in the absorbance spectra of camphor and (-)-isopulegol.

With the VUV detector, each compound exhibits its own unique absorbance spectrum. Even isomers and isobars, which are prevalent in terpene mixtures and can be difficult to distinguish different species by their electron ionization mass spectra, can be well differentiated based on their VUV spectra 6,9,10.  Nevertheless, because analytes exhibit different spectra, it is not required to achieve a perfect chromatographic separation of the mixture components. Co-eluting peaks can be separated post-run through the use of library spectra and software inherent to the instrument 4,10. This ability is called “deconvolution”, and it is based on the fact that two co-eluting terpenes will give a peak with an absorbance spectrum equal to the sum of the two single absorbance spectra 4. Figure 1 shows the deconvolution process for two co-eluting terpenes, camphor and (-)-isopulegol. Due to their different absorbance spectra (Figure 1C), it is possible to fully separate the two peaks in post-run, obtaining sharp peaks for both analytes 6.

The deconvolution process has been shown to yield precise and accurate results. Thus, chromatographic resolution can be sacrificed in favor of spectroscopic resolution; this enables the development of methods with faster run times. With the ability to deconvolve unresolved peaks, a long temperature ramp to chromatographically separate all isomeric terpenes is not required 6. Additionally, the presence of coeluting components, which might normally go undetected with some GC detectors, can be easily judged based on comparison of the measured spectra with pure reference spectra contained in the VUV spectral library.

The other issue in terpenes analysis is the extraction process. Terpenes can be extracted with the use of solvents (e.g., methanol, ethanol, hexane, and cyclohexane, among others), but the process is usually time-consuming, costly and not so environmentally-friendly 2. The plant needs to be manually crushed and then aliquots of solvent are used to extract components from the plant, ideally at least 3 times and combined to achieve acceptable results. The problem is that some terpenes may respond better to a certain solvent, making their extraction easier and more optimized than for others 2. The choice of solvent can cause discrimination against the extraction some terpenes, which limits the comprehensiveness of analysis.

Headspace is another technique that can be used for the sample preparation of terpenes. Headspace sampling is based on heating the solid or liquid sample inside a sealed vial, and then analyzing the air above it after sufficient equilibration. In this way, only volatile analytes are extracted from the solid/liquid sample into the gas phase; this allows relatively interference-free sampling 12–14.

How do we know whether our extraction analysis methods are correct and comprehensive for a certain plant sample? Unfortunately, there is not a complete list of available molecules for each plant species, and even if two specimens may smell really similar to our nose, their terpenes profiles may be notably different. When working with a new plant material, it is difficult to predict the extraction efficiency for the vast array of terpenes that may be present. We can only perform it with different extraction and detection methods, and compare the results.

The route for a comprehensive and fast analysis of terpenes is therefore still long; however, their intoxicating aromas and inherent medicinal value has provided a growing impetus for researchers around the world. Considering the evolving importance of Cannabis and the growing body of evidence on the synergistic effects between terpenes and cannabinoids, it is likely that newly improved extraction and analysis methods will be developed, paving the way for a more complete list of terpene species that can be found in different cultivars. The use of new analytical technologies, such as the VUV detector for GC, should aid considerably in this endeavor.


References:

[1]          Breitmaier E., Terpenes: Flavors, Fragrances, Pharmaca, Pheromones. John Wiley & Sons 2006.

[2]          Leghissa A., Hildenbrand Z. L., Schug K. A., A Review of Methods for the Chemical Characterization of Cannabis Natural Products. J. Sep. Sci.2018, 41, 398–415 .

[3]          Benvenuto E., Misra B. B., Stehle F., Andre C. M., Hausman J.-F., Guerriero G., Cannabis sativa: The Plant of the Thousand and One Molecules. Front. Plant Sci2016, 719, DOI: 10.3389/fpls.2016.00019.

[4]          Schug K. A., Sawicki I., Carlton D. D., Fan H.,Mcnair H. M.,Nimmo J. P., Kroll P.,Smuts J.,Walsh P., Harrison D., Vacuum Ultraviolet Detector for Gas Chromatography. Anal. Chem.2014, 86, 8329–8335 .

[5]          Fan H.,Smuts J., Walsh P.,Harrison D., Schug K. A., Gas chromatography-vacuum ultraviolet spectroscopy for multiclass pesticide identification. J. Chromatogr. A2015, DOI: 10.1016/j.chroma.2015.02.035.

[6]          Qiu C.,Smuts J., Schug K. A., Analysis of terpenes and turpentines using gas chromatography with vacuum ultraviolet detection. J. Sep. Sci.2017, 40, 869–877 .

[7]          Leghissa A., Smuts J., Qiu C., Hildenbrand Z. L., Schug K. A., Detection of cannabinoids and cannabinoid metabolites using gas chromatography-vacuum ultraviolet spectroscopy. Sep. Sci. Plus2018, 1.

[8]          Bai L.,Smuts J., Walsh P., Fan H., Hildenbrand Z., Wong D., Wetz D., Schug K. A., Permanent gas analysis using gas chromatography with vacuum ultraviolet detection. J. Chromatogr. A2015,1388, 244–250 .

[9]          Skultety L., Frycak P., Qiu C.,Smuts J., Shear-Laude L., Lemr K., Mao J. X., Kroll P., Schug K. A., Szewczak A., Vaught C., Lurie I., Havlicek V., Resolution of isomeric new designer stimulants using gas chromatography – Vacuum ultraviolet spectroscopy and theoretical computations. Anal. Chim. Acta2017, 971, 55–67 .

[10]       Bai L., Smuts J., Walsh P., Qiu C., McNair H. M., Schug K. ., Pseudo-absolute quantitative analysis using gas chromatography–vacuum ultraviolet spectroscopy–a tutorial. Anal. Chim. Acta2017, 953, 10–22 .

[11]       Schenk J., Nagy G., Pohl N. L. B., Leghissa A., Smuts J., Schug K. A., Identification and deconvolution of carbohydrates with gas chromatography-vacuum ultraviolet spectroscopy. J. Chromatogr. A2017, 1513, 210–221 .

[12]       Van Opstaele F., De Causmaecker B., Aerts G., De Cooman L., Characterization of novel varietal floral hop aromas by headspace solid phase microextraction and gas chromatography-mass spectrometry/olfactometry. J. Agric. Food Chem.2012, 60, 12270−12281 .

[13]       Hamm S., Bleton J., Connan J., Tchapla A., A chemical investigation by headspace SPME and GC-MS of volatile and semi-volatile terpenes in various olibanum samples. Phytochemistry2005,66, 1499–1514 .

[14]       Aberl A., Coelhan M., Determination of volatile compounds in different hop Varieties by headspace-trap GC/MS-in comparison with conventional hop essential oil analysis. J. Agric. Food Chem.2012, 60, 2785−2792 .

Soapbox

Poland Legalizes Medical Cannabis

By Marguerite Arnold
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Poland has now legalized cannabis for medical purposes.

That said, it will be some time before patients have access to the drug. While Poles can now technically access medical pot, the scheme approved by the Polish Parliament that went into effect on November 1st is regressive, to say the least. Certainly compared with even other countries in Europe that are now finally admitting that cannabis is a drug with medical efficacy, the Polish experiment looks “old-fashioned.”

What Does Medical Cannabis Reform Look Like in Poland?

Like most conservative countries, Poland is sticking with a highly restrictive approach that still puts patients in the hot seat. In addition to getting a doctor’s prescription, the chronically ill must be approved by a state authority – a regional pharmaceutical inspector. They must get a license first, in other words. They must then find about $500 a month to pay for cannabis. To put this in perspective, that is roughly the total amount such patients get from the state to live on each month.

Warsaw, Poland
Image: Nikos Roussos, Flickr

The multiple steps mean that only patients with financial resources– and an illness which is chronic but still allows them to negotiate the many government hurdles, including cost –will now be able to access medical cannabis. Unlike Germany which makes no such distinctions, Polish law now recognizes the drug as an effective form of treatment only for chronic pain, chemo-induced nausea, MS and drug-resistant epilepsy.

The heavily amended legislation also outlaws home growing. And while 90% of pharmacies will be able to dispense the drug, this is again, a technicality. Where will the pharmacies get the cannabis in the first place?

So the question remains: will this step really mean reform? There is no medical cultivation planned. And no companies (yet) have been licensed to import the drug.

This is what is clear. Much like the conversation in Georgia and other southern American states several years ago, legislators are bowing to popular demand if not scientific evidence, to legalize medical use. But patients still cannot get it – even if they jump through all the hoops.

In Poland, patients who cannot find legal cannabis in the country (which is all of them at this point) now do have the right to travel to other EU countries in search of medicine. But the unanswered question in all of this is still present. How, exactly is this supposed to work? Patients must come up with the money to pay for their medical cannabis (at local prices) plus regular transportation costs. Then they must pay sky high fees to access local doctors (if they can find them) at “retail cost” uncovered by any insurance.

The issue of countries legalizing cannabis on paper, but not in action, is a problem now facing legalization advocates in the EUThe most obvious route for Polish patients with resources and the ability to travel is Germany. The catch? Medical cannabis costs Just on this front, the idea of regular country hopping for script refills – even if “just” across the border – is ludicrous. And who protect such patients legally if caught at the border, with a three month supply?

Poland, in other words, has adopted something very similar to Georgia’s regulations circa 2015. Medical cannabis is now technically legal but still inaccessible because of cost and logistics. Reform, Polish-style, appears to actually just be more window-dressing.

And while it is an obvious step for the country to start issuing import licenses to Canadian, Israeli and Australian exporters, how long will that take?

The Next Step Of Reform – Unfettered Patient Access

While things are still bad in Poland, right across the border in Germany where presumably Polish patients could theoretically buy their medical cannabis, all is still not copacetic. Even for the “locals.” Germany’s situation remains dire. But even before legalization in March, Germany was importing bud cannabis from Holland and began a trickle of imports last summer from Canada. That trickle has now expanded considerably with new import licences this year. And presumably, although nobody is sure, there will be some kind of domestic cultivation by 2019.

At Deutsche Hanfverband’s Cannabis Normal activist’s conference in Berlin held on the same weekend as Poland decided to legalize medical cannabis, a Gen X patient expressed his frustration with the situation of legalization in general. Oliver Waack-Jurgensen is now suing his German public insurer. He expects to wait another year and a half before he wins. In the meantime, he is organizing other patients. “They [political representatives] are bowing to political expediency but completely ignoring patient needs,” says Waack-Jurgensen. “How long is this conversation going to take? I am tired of it. Really, really tired of this.”

The issue of countries legalizing cannabis on paper, but not in action, is a problem now facing legalization advocates in the EU and elsewhere who have achieved legislative victories, but still realize this is an unfinished battle. Germany is the only country in Europe with a federal mandate to cover the drug under insurance (for Germans only). And that process is taking time to implement.But even in Germany, patients are having to sue their insurance companies

Germany, Italy and Turkey are also the only countries in Europe as of now with any plans to grow the drug domestically under a federally mandated regulation scheme. Import from Holland, Canada and even Australia appears to be the next step in delaying full and unfettered reform in Europe. See Croatia, Slovenia and Bosnia. How Spanish or Portuguese-grown cannabis will play into this discussion is also an open question mark. Asking Polish patients suffering from cancer to “commute” to Portugal is also clearly unfeasible.

Unlike the United States, however, European countries do have public healthcare systems, which are supposed to cover the majority of the population. What gives? And what is likely to happen?

A Brewing Battle At The EU Human Rights Court?

While the Polish decision to “legalize” medical use is a step in the right direction, there is still a long way to go. If the idea is to halt the black market trade, giving patients real access is a good idea. But even in Germany, patients are having to sue their insurance companies. And are now doing so in large numbers. In a region where lawsuits are much less common than the U.S., this is shocking enough.

But the situation is so widespread and likely to continue for some time, that class action lawsuits – and on the basis of human rights violations over lack of access to a life-saving drug – may finally come to the continent and at an EU (international) level court.

Patients are literally dying in the meantime. And those who aren’t are joining the calls for hunger strikes and other direct civil action. Sound far-fetched? There is legal precedent. See Mexico.

And while Poland may or may not be the trigger for this kind of concerted legal action, this idea is clearly gathering steam in advocacy circles across Europe.

Quality Assurance In The Field: Instruments For Growers & Processors

By Aaron G. Biros
2 Comments

As the cannabis marketplace evolves, so does the technology. Cultivators are scaling up their production and commercial-scale operations are focusing more on quality. That greater attention to detail is leading growers, extractors and infused product manufacturers to use analytical chemistry as a quality control tool.

Previously, using analytical instrumentation, like mass spectrometry (MS) or gas chromatography (GC), required experience in the laboratory or with chromatography, a degree in chemistry or a deep understanding of analytical chemistry. This leaves the testing component to those that are competent enough and scientifically capable to use these complex instruments, like laboratory personnel, and that is still the case. As recent as less than two years ago, we began seeing instrument manufacturers making marketing claims that their instrument requires no experience in chromatography.

Instrument manufacturers are now competing in a new market: the instrument designed for quality assurance in the field. These instruments are more compact, lighter and easier to use than their counterparts in the lab. While they are no replacement for an accredited laboratory, manufacturers promise these instruments can give growers an accurate estimate for cannabinoid percentages. Let’s take a look at a few of these instruments designed and marketed for quality assurance in the field, specifically for cannabis producers.

Ellutia GC 200 Series

Shamanics, a cannabis extractor in Amsterdam, uses Ellutia’s 200 series for QA testing

Ellutia is an instrument manufacturer from the UK. They design and produce a range of gas chromatographs, GC accessories, software and consumables, most of which are designed for use in a laboratory. Andrew James, marketing director at Ellutia, says their instrument targeting this segment was originally designed for educational purposes. “The GC is compact in size and lightweight in stature with a full range of detectors,” says James. “This means not only is it portable and easy to access but also easy to use, which is why it was initially intended for the education market.”

Andrew James, marketing director at Ellutia

That original design for use in teaching, James says, is why cannabis producers might find it so user-friendly. “It offers equivalent performance to other GC’s meaning we can easily replace other GC’s performing the same analysis, but our customers can benefit from the lower space requirement, reduced energy bills, service costs and initial capital outlay,” says James. “This ensures the lowest possible cost of ownership, decreasing the cost per analysis and increasing profits on every sample analyzed.”

Shamanics, a cannabis oil extraction company based in Amsterdam, uses Ellutia’s 200 series for quality assurance in their products. According to Bart Roelfsema, co-founder of Shamanics, they have experienced a range of improvements in monitoring quality since they started using the 200 series. “It is very liberating to actually see what you are doing,” says Roelfsema. “If you are a grower, a manufacturer or a seller, it is always reassuring to see what you have and prove or improve on your quality.” Although testing isn’t commonplace in the Netherlands quite yet, the consumer demand is rising for tested products. “We also conduct terpene analysis and cannabinoid acid analysis,” says Roelfsema. “This is a very important aspect of the GC as now it is possible to methylate the sample and test for acids; and the 200 Series is very accurate, which is a huge benefit.” Roelfsema says being able to judge quality product and then relay that information to retail is helping them grow their business and stay ahead of the curve.

908 Devices G908 GC-HPMS

908 Devices, headquartered in Boston, is making a big splash in this new market with their modular G908 GC-HPMS. The company says they are “democratizing chemical analysis by way of mass spectrometry,” with their G908 device. That is a bold claim, but rather appropriate, given that MS used to be reserved strictly for the lab environment. According to Graham Shelver, Ph.D., commercial leader for Applied Markets at 908 Devices Inc., their company is making GC-HPMS readily available to users wanting to test cannabis products, who do not need to be trained analytical chemists.

The G908 device.

Shelver says they have made the hardware modular, letting the user service the device themselves. This, accompanied by simplified software, means you don’t need a Ph.D. to use it. “The “analyzer in a box” design philosophy behind the G908 GC-HPMS and the accompanying JetStream software has been to make using the entire system as straightforward as possible so that routine tasks such as mass axis calibration are reduced to simple single actions and sample injection to results reporting becomes a single button software operation,” says Shelver.

He also says while it is designed for use in the field, laboratories also use it to meet higher-than-usual demand. Both RM3 Labs in Colorado, and ProVerde in Massachusetts, use G908. “RM3’s main goal with the G908 is increased throughput and ProVerde has found it useful in adding an orthogonal and very rapid technique (GC-HPMS) to their suite of cannabis testing instruments,” says Shelver.

Orange Photonics LightLab Cannabis Analyzer

Orange Photonics’ LightLab Cannabis Analyzer

Dylan Wilks, a third generation spectroscopist, launched Orange Photonics with his team to produce analytical tools that are easy to use and can make data accessible where it has been historically absent, such as onsite testing within the cannabis space. According to Stephanie McArdle, president of Orange Photonics, the LightLab Cannabis Analyzer is based on the same principles as HPLC technology, combining liquid chromatography with spectroscopy. Unlike an HPLC however, LightLab is rugged, portable and they claim you do not need to be a chemist to use it.

“LightLab was developed to deliver accurate repeatable results for six primary cannabinoids, D9THC, THC-A, CBD, CBD-A, CBG-A and CBN,” says McArdle. “The sample prep is straightforward: Prepare a homogenous, representative sample, place a measured portion in the provided vial, introduce extraction solvent, input the sample into LightLab and eight minutes later you will have your potency information.” She says their goal is to ensure producers can get lab-grade results.

The hard plastic case is a unique feature of this instrument

McArdle also says the device is designed to test a wide range of samples, allowing growers, processors and infused product manufacturers to use it for quality assurance. “Extracts manufacturers use LightLab to limit loss- they accurately value trim purchases on the spot, they test throughout their extraction process including tests on spent material (raffinate) and of course the final product,” says McArdle. “Edibles manufacturers test the potency of their raw ingredients and check batch dosing. Cultivators use LightLab for strain selection, maturation monitoring, harvesting at peak and tinkering.”

Orange Photonics’ instrument also connects to devices via Wi-Fi and Bluetooth. McArdle says cannabis companies throughout the supply chain use it. “We aren’t trying to replace lab testing, but anyone making a cannabis product is shooting in the dark if they don’t have access to real time data about potency,” says McArdle.

The Practical Chemist

Instrumentation Used for Terpene Analysis

By Tim Herring
2 Comments

Terpenes are a group of volatile, unsaturated hydrocarbons found in the essential oils of plants. They are responsible for the characteristic smells and flavors of most plants, such as conifers, citrus, as well as cannabis. Over 140 terpenes have been identified to date and these unique compounds may have medicinal properties. Caryophyllene, for example, emits a sweet, woody, clove taste and is believed to relieve inflammation and produce a neuroprotective effect through CB2 receptor activation. Limonene has a citrus scent and may possess anti-cancer, anti-bacterial, anti-fungal and anti-depression effects. Pinene is responsible for the pine aroma and acts as a bronchodilator. One theory involving terpenes is the Entourage Effect, a synergistic benefit from the combination of cannabinoids and terpenes.

Many customers ask technical service which instrumentation is best, GC or HPLC, for analysis of terpenes. Terpenes are most amenable to GC, due to their inherent volatility. HPLC is generally not recommended; since terpenes have very low UV or MS sensitivity; the cannabinoids (which are present in percent levels) will often interfere or coelute with many of the terpenes.

Figure 1: Terpene profile via headspace, courtesy of ProVerde Laboratories.

Headspace (HS), Solid Phase Microextraction of Headspace (HS-SPME) or Split/Splitless Injection (SSI) are viable techniques and have advantages and disadvantages. While SPME can be performed by either direct immersion with the sample or headspace sampling, HS-SPME is considered the most effective technique since this approach eliminates the complex oil matrix. Likewise, conventional HS also targets volatiles that include the terpenes, leaving the high molecular weight oils and cannabinoids behind (Figure 1). SSI eliminates the complexity of a HS or SPME concentrator/autosampler, however, sensitivity and column lifetime become limiting factors to high throughput, since the entire sample is introduced to the inlet and ultimately the column.

The GC capillary columns range from thicker film, mid-polarity (Rxi-624sil MS for instance) to thinner film, non-polar 100% polysiloxane-based phases, such as an Rxi-1ms. A thicker film provides the best resolution among the highly volatile, early eluting compounds, such as pinene. Heavier molecular weight compounds, such as the cannabinoids, are difficult to bake off of the mid-polarity phases. A thinner, non-polar film enables the heavier terpenes and cannabinoids to elute efficiently and produces sharp peaks. Conversely the early eluting terpenes will often coelute using a thin film column. Columns that do not contain cyano-functional groups (Rxi-624Sil MS), are more robust and have higher temperature limits and lower bleed.

For the GC detector, a Mass Spectrometer (MS) can be used, however, many of the terpenes are isobars, sharing the same ions used for identification and quantification. Selectivity is the best solution, regardless of the detector. The Flame Ionization Detector (FID) is less expensive to purchase and operate and has a greater dynamic range, though it is not as sensitive, nor selective for coeluting impurities.

By accurately and reproducibly quantifying terpenes, cannabis medicines can be better characterized and controlled. Strains, which may exhibit specific medical and psychological traits, can be identified and utilized to their potential. The lab objectives, customer expectations, state regulations, available instrumentation, and qualified lab personnel will ultimately determine how the terpenes will be analyzed.

Chris English
The Practical Chemist

Accurate Detection of Residual Solvents in Cannabis Concentrates

By Chris English
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Chris English

Edibles and vape pens are rapidly becoming a sizable portion of the cannabis industry as various methods of consumption popularize beyond just smoking dried flower. These products are produced using cannabis concentrates, which come in the form of oils, waxes or shatter (figure 1). Once the cannabinoids and terpenes are removed from the plant material using solvents, the solvent is evaporated leaving behind the product. Extraction solvents are difficult to remove in the low percent range so the final product is tested to ensure leftover solvents are at safe levels. While carbon dioxide and butane are most commonly used, consumer concern over other more toxic residual solvents has led to regulation of acceptable limits. For instance, in Colorado the Department of Public Health and Environment (CDPHE) updated the state’s acceptable limits of residual solvents on January 1st, 2017.

Headspace Analysis

Figure 1: Shatter can be melted and dissolved in a high molecular weight solvent for headspace analysis (HS). Photo Courtesy of Cal-Green Solutions.

Since the most suitable solvents are volatile, these compounds are not amenable to HPLC methods and are best suited to gas chromatography (GC) using a thick stationary phase capable of adequate retention and resolution of butanes from other target compounds. Headspace (HS) is the most common analytical technique for efficiently removing the residual solvents from the complex cannabis extract matrix. Concentrates are weighed out into a headspace vial and are dissolved in a high molecular weight solvent such as dimethylformamide (DMF) or 1,3-dimethyl-3-imidazolidinone (DMI). The sealed headspace vial is heated until a stable equilibrium between the gas phase and the liquid phase occurs inside the vial. One milliliter of gas is transferred from the vial to the gas chromatograph for analysis. Another approach is full evaporation technique (FET), which involves a small amount of sample sealed in a headspace vial creating a single-phase gas system. More work is required to validate this technique as a quantitative method.

Gas Chromatographic Detectors

The flame ionization detector (FID) is selective because it only responds to materials that ionize in an air/hydrogen flame, however, this condition covers a broad range of compounds. When an organic compound enters the flame; the large increase in ions produced is measured as a positive signal. Since the response is proportional to the number of carbon atoms introduced into the flame, an FID is considered a quantitative counter of carbon atoms burned. There are a variety of advantages to using this detector such as, ease of use, stability, and the largest linear dynamic range of the commonly available GC detectors. The FID covers a calibration of nearly 5 orders of magnitude. FIDs are inexpensive to purchase and to operate. Maintenance is generally no more complex than changing jets and ensuring proper gas flows to the detector. Because of the stability of this detector internal standards are not required and sensitivity is adequate for meeting the acceptable reporting limits. However, FID is unable to confirm compounds and identification is only based on retention time. Early eluting analytes have a higher probability of interferences from matrix (Figure 2).

Figure 2: Resolution of early eluting compounds by headspace – flame ionization detection (HS-FID). Chromatogram Courtesy of Trace Analytics.

Mass Spectrometry (MS) provides unique spectral information for accurately identifying components eluting from the capillary column. As a compound exits the column it collides with high-energy electrons destabilizing the valence shell electrons of the analyte and it is broken into structurally significant charged fragments. These fragments are separated by their mass-to-charge ratios in the analyzer to produce a spectral pattern unique to the compound. To confirm the identity of the compound the spectral fingerprint is matched to a library of known spectra. Using the spectral patterns the appropriate masses for quantification can be chosen. Compounds with higher molecular weight fragments are easier to detect and identify for instance benzene (m/z 78), toluene (m/z 91) and the xylenes (m/z 106), whereas low mass fragments such as propane (m/z 29), methanol (m/z 31) and butane (m/z 43) are more difficult and may elute with matrix that matches these ions. Several disadvantages of mass spectrometers are the cost of equipment, cost to operate and complexity. In addition, these detectors are less stable and require an internal standard and have a limited dynamic range, which can lead to compound saturation.

Regardless of your method of detection, optimized HS and GC conditions are essential to properly resolve your target analytes and achieve the required detection limits. While MS may differentiate overlapping peaks the chances of interference of low molecular weight fragments necessitates resolution of target analytes chromatographically. FID requires excellent resolution for accurate identification and quantification.

The Practical Chemist

Pesticide Analysis in Cannabis and Related Products: Part 3

By Julie Kowalski
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As mentioned in Part 1, pesticides residue analysis is very challenging especially considering the complexity of cannabis and the variety of flower, concentrates and infused products. In addition, pesticides are tested at low levels typically at parts-per-billion (ppb). For example, the food safety industry often uses 10 ppb as a benchmark limit of quantification. To put that in perspective, current pesticides limits in cannabis range from 10 ppb default (Massachusetts Regulatory Limit) to a more typical range of 100 ppb to 2 ppm in other states. Current testing is also complicated by evolving regulations.

Despite these challenges, adaptation of methods used by the food safety industry have proved successful for testing pesticides in cannabis. These methods typically rely on mass spectrometric detection paired with sample preparation methods to render the sample clean enough to yield quality data.

Pesticide Analysis Methods: Sample preparation and Analytical Technique Strategy

Generally, methods can be divided into two parts; sample preparation and analytical testing where both are critical to the success of pesticide residue testing and are inextricably linked. Reliance on mass spectrometric techniques like tandem mass spectrometry and high resolution accurate mass (HRAM) mass spectrometry is attributed to the substantial sensitivity and selectivity provided. The sensitivity and selectivity achievable by the detector largely dictates the sample preparation that will be required. The more sensitive and selective the detector, the less rigorous and resource intensive sample preparation can be.

Analytical technique: Gas and Liquid Chromatography Tandem Mass Spectrometry 

The workhorse approach for pesticide residue analysis involves using gas chromatography and liquid chromatography tandem mass spectrometry (MS/MS) in the ion transition mode. This ion transition mode, often referred to as multiple reaction monitoring (MRM) or selected reaction monitoring (SRM), adds the selectivity and sensitivity needed for trace level analysis. Essentially, a pesticide precursor ion is fragmented into product ions. The detector monitors the signal for a specified product ion known to have originated from the pesticide precursor ion. This allows the signal to be corrected, associated with the analyte and not with other matrix components in the sample. In addition, because only ions meeting the precursor/product ion requirements are passed to the detector with little noise, there is a benefit to the observed signal to noise ratio allowing better sensitivity than in other modes. Even though ion transitions are specific, there is the possibility a matrix interference that also demonstrates that same ion transition could result in a false positive. Multiple ion transitions for each analyte are monitored to determine an ion ratio. The ion ratio should remain consistent for a specific analyte and is used to add confidence to analyte identification.

The best choice for pesticide analysis between gas chromatography (GC) and liquid chromatography (LC) is often questioned. To perform comprehensive pesticide screening similar to the way the food safety market approaches this challenge requires both techniques. It is not uncommon for screening methods to test for several hundred pesticides that vary in physiochemical properties. It may be possible that with a smaller list of analytes, only one technique will be needed but often in order to reach the low limits for pesticide residues both GC and LC are required.

Modified QuEChERS extraction using 1.5 grams of cannabis flower. Courtesy of Julie Kowalski (Restek Corporation), Jeff Dahl (Shimadzu Scientific Instruments) and Derek Laine (Trace Analytics).
Modified QuEChERS extraction using 1.5 grams of cannabis flower. Courtesy of Julie Kowalski (Restek Corporation), Jeff Dahl (Shimadzu Scientific Instruments) and Derek Laine (Trace Analytics).

Analytical technique: Sample Preparation

Less extensive sample preparation is possible when combined with sensitive and selective detectors like MS/MS. One popular method is the QuEChERS approach. QuEChERS stands for Quick, Easy, Cheap, Effective, Rugged and Safe. It consists of a solvent extraction/salting out step followed by a cleanup using dispersive solid phase extraction. Originally designed for fruit and vegetable pesticide testing, QuEChERS has been modified and used for many other commodity types including cannabis. Although QuEChERS is a viable method, sometimes more cleanup is needed and this can be done with cartridge solid phase extraction. This cleanup functions differently and is more labor intensive, but results in a cleaner extract. A cleaner extract helps to secure quality data and is sometimes needed for difficult analyses.