Tag Archives: mass spec

Multi-Element Analysis Using ICP-MS: A Look at Heavy Metals Testing

By Cannabis Industry Journal Staff
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Across the country and across the world, governments that legalize cannabis implement increasingly rigorous requirements for laboratory testing. Helping to protect patients and consumers from contaminants, these requirements involve a slew of lab tests, including quantifying the levels of microbial contaminants, pathogens, mold and heavy metals.

Cannabis and hemp have a unique ability to accumulate elements found in soil, which is why these plants can be used as effective tools for bioremediation. Because cannabis plants have the ability to absorb potentially toxic and dangerous elements found in the soil they grow in, lab testing regulations often include the requirement for heavy metals testing, such as Cadmium, Lead, Mercury, Arsenic and others.

In addition to legal cannabis markets across the country, the USDA announced the establishment of the U.S. Domestic Hemp Production Program, following the enactment of the 2018 Farm Bill, essentially legalizing hemp. This announcement comes with information for hemp testing labs, including testing and sampling guidelines. While the information available on the USDA’s website only touches on testing for THC, required to be no greater than 0.3% dry weight concentration, more testing guidelines in the future are sure to include a discussion of heavy metals testing.

Table 1. ICP-MS operating conditions (shaded parameters were automatically optimized during start up for the HMI conditions).

In an application note produced by Agilent Technologies, Inc., the Agilent 7800 ICP-MS was used to analyze 25 elements in a variety of cannabis and hemp-derived products. The study was conducted using that Agilent 7800 ICP-MS, which includes Agilent’s proprietary High Matrix Introduction (HMI) system. The analysis was automated  by using the Agilent SPS 4 autosampler.

Instrumentation

The instrument operating conditions can be found in Table 1. In this study, the HMI dilution factor was 4x and the analytes were all acquired in the Helium collision mode. Using this methodology, the Helium collision mode consistently reduces or completely eliminates all common polyatomic interferences using kinetic energy discrimination (KED).

Table 2. Parameters for microwave digestion.

As a comparison, Arsenic and Selenium were also acquired via the MassHunter Software using half-mass correction, which corrects for overlaps due to doubly charged rare earth elements. This software also collects semiquantitative or screening data across the entire mass region, called Quick Scan, showing data for elements that may not be present in the original calibration standards.

SRMs and Samples

Standard reference materials (SRMs) analyzed from the National Institute of Standards and Technology (NIST) were used to verify the sample prep digestion process. Those included NIST 1547 Peach Leaves, NIST 1573a Tomato Leaves and NIST 1575 Pine Needles. NIST 1640a Natural Water was also used to verify the calibration.

Figure 1. Calibration curves for As, Cd, Pb, and Hg.

Samples used in the study include cannabis flower, cannabis tablets, a cannabidiol (CBD) tincture, chewable candies and hemp-derived cream.

Sample Preparation

Calibration standards were prepared using a mix of 1% HNO3 and 0.5% HCl. Sodium, Magnesium, Potassium, Calcium and Iron were calibrated from 0.5 to 10 ppm. Mercury was calibrated from 0.05 to 2 ppb. All the other elements were calibrated from 0.5 to 100 ppb.

Table 3. Calibration summary data acquired in He mode. Data for As and Se in shaded cells was obtained using half mass correction tuning.

After weighing the samples (roughly 0.15 g of cannabis plant and between 0.3 to 0.5 g of cannabis product) into quartz vessels, 4 mL HNO3 and 1 mL HCl were added and the samples were microwave digested using the program found in Table 2.

HCI was included to ensure the stability of Mercury and Silver in solution. They diluted the digested samples in the same acid mix as the standards. SRMs were prepared using the same method to verify sample digestion and to confirm the recovery of analytes.

Four samples were prepared in triplicate and fortified with the Agilent Environmental Mix Spike solution prior to the analysis. All samples, spikes and SRMs were diluted 5x before testing to reduce the acid concentration.

Calibration

Table 4. ICV and CCV recovery tests. Data for As and Se in shaded cells was obtained using half mass correction tuning.

The calibration curves for Arsenic, Cadmium, Lead and Mercury can be found in Figure 1 and a summary of the calibration data is in Table 3. For quality control, the SRM NIST 1645a Natural Water was used for the initial calibration verification standard.  Recoveries found in Table 4 are for all the certified elements present in SRM NIST 1640a. The mean recoveries and concentration range can also be found in Table 4. All the continuing calibration solution recoveries were within 10% of the expected value.

Internal Standard Stability

Figure 2 highlights the ISTD signal stability for the sequence of 58 samples analyzed over roughly four hours. The recoveries for all samples were well within 20 % of the value in the initial calibration standard.

Figure 2. Internal standard signal stability for the sequence of 58 samples analyzed over ~four hours.

Results

In Table 5, you’ll find that three SRMs were tested to verify the digestion process. The mean results for most elements agreed with the certified concentrations, however the results for Arsenic in NIST 1547 and Selenium in both NIST 1547 and 1573a did not show good agreement due to interreferences formed from the presence of doubly-charged ions

Table 5. Mean concentrations (ppm) of three repeat measurements of three SRMs, including certified element concentrations, where appropriate, and % recovery.

Some plant materials can contain high levels of rare earth elements, which have low second ionization potentials, so they tend to form doubly-charged ions. As the quadrupole Mass Spec separates ions based on their mass-to-charge ratio, the doubly-charged ions appear at half of their true mass. Because of that, a handful of those doubly-charged ions caused overlaps leading to bias in the results for Arsenic and Selenium in samples that have high levels of rare earth elements. Using half mass correction, the ICP-MS corrects for these interferences, which can be automatically set up in the MassHunter software. The shaded cells in Table 5 highlight the half mass corrected results for Arsenic and Selenium, demonstrating recoveries in agreement with the certified concentrations.

In Table 6, you’ll find the quantitative results for cannabis tablets and the CBD tincture. Although the concentrations of Arsenic, Cadmium, Lead and Cobalt are well below current regulations’ maximum levels, they do show up relatively high in the cannabis tablets sample. Both Lead and Cadmium also had notably higher levels in the CBD tincture as well.

Table 6. Quantitative data for two cannabis-related products and two cannabis samples plus mean spike recovery results. All units ppb apart from major elements, which are reported as ppm.

A spike recovery test was utilized to check the accuracy of the method for sample analysis. The spike results are in Table 6.

Using the 7800 ICP-MS instrument and the High Matrix Introduction system, labs can routinely analyze samples that contain high and very variable matrix levels. Using the automated HMI system, labs can reduce the need to manually handle samples, which can reduce the potential for contamination during sample prep. The MassHunter Quick Scan function shows a complete analysis of the heavy metals in the sample, including data reported for elements not included in the calibration standards.

The half mass correction for Arsenic and Selenium allows a lab to accurately determine the correct concentrations. The study showed the validity of the microwave sample prep method with good recovery results for the SRMs. Using the Agilent 7800 ICP-MS in a cannabis or hemp testing lab can be an effective and efficient way to test cannabis products for heavy metals. This test can be used in various stages of the supply chain as a tool for quality controls in the cannabis and hemp markets.

Disclaimer: Agilent products and solutions are intended to be used for cannabis quality control and safety testing in laboratories where such use is permitted under state/country law.

PerkinElmer Awarded Five Emerald Test Badges

By Aaron G. Biros
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According to a press release published today, Emerald Scientific awarded PerkinElmer five badges for The Emerald Test, a bi-annual Inter-Laboratory Comparison and Proficiency Test (ILC/PT) program. Awarding the badges for Perkin Elmer’s instruments and testing methods affirms their ability to accurately detect pesticides, heavy metals, residual solvents, terpenes and potency in cannabis.

According to Greg Sears, vice president and general manager of Food, Chromatography & Mass Spectrometry, Discovery & Analytical Solutions at PerkinElmer, they are the only instrument manufacturer to receive all five accolades. “To date, PerkinElmer is the only solutions provider to successfully complete these five Emerald Scientific proficiency tests,” says Sears. “The badges underscore our instruments’ ability to help cannabis labs meet the highest standards available in the industry and effectively address their biggest pain point: Navigating diverse regulations without compromising turnaround time.”

The instruments used were PerkinElmer’s QSight 220 and 420 Triple Quad systems, which are originally designed for accurate and fast detection/identification of “pesticides, mycotoxins and emerging contaminants in complex food, cannabis and environmental samples,” reads the press release. They also used their ICP-MS, GC/MS and HPLC systems for the badges.

PerkinElmer says they developed a single LC/MS/MS method using their QSight Triple Quad systems, which helps labs test for pesticides and mycotoxins under strict regulations in states like California and Oregon. They performed studies that also confirm their instruments can help meet Canada’s testing requirements, which set action limits nearly 10 times lower than California, according to the press release.

Heavy Metals 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, Laurie Post, Director of Food Safety & Compliance, and Charles Deibel, President Deibel Cannabis Labs.

Heavy metals are common environmental contaminants resulting from human industrial activities such as mining operations, industrial waste, automotive emissions, coal fired power plants and farm/house hold water run-off. They affect the water and soil, and become concentrated in plants, animals, pesticides and the sediments used to make fertilizers. They can also be present in low quality glass or plastic packaging materials that can leach into the final cannabis product upon contact. The inputs used by cultivators that can be contaminated with heavy metals include fertilizers, growing media, air, water and even the clone/plant itself.

The four heavy metals tested in the cannabis industry are lead, arsenic, mercury and cadmium. The California Bureau of Cannabis Control (BCC) mandates heavy metals testing for all three categories of cannabis products (inhalable cannabis, inhalable cannabis products and other cannabis and cannabis products) starting December 31, 2018. On an ongoing basis, we recommend cultivators test for the regulated heavy metals in R&D samples any time there are changes in a growing process including changes to growing media, cannabis strains, a water system or source, packaging materials and fertilizers or pesticides. Cultivators should test the soil, nutrient medium, water and any new clones or plants for heavy metals. Pre-qualifying a new packaging material supplier or a water source prior to use is a proactive approach that could bypass issues with finished product.

Testing Strategies

The best approach to heavy metal detection is the use of an instrument called an Inductively Coupled Plasma Mass Spectrometry (ICP-MS). There are many other instruments that can test for heavy metals, but in order to achieve the very low detection limits imposed by most states including California, the detector must be the ICP-MS. Prior to detection using ICP-MS, cannabis and cannabis related products go through a sample preparation stage consisting of some form of digestion to completely break down the complex matrix and extract the heavy metals for analysis. This two-step process is relatively fast and can be done in a single day, however, the instruments used to perform the digestion are usually the limiting step as the digesters run in a batch of 8-16 samples over a 2-hour period.

Only trace amounts of heavy metals are allowed by California’s BCC in cannabis and cannabis products. A highly sensitive detection system finds these trace amounts and also allows troubleshooting when a product is found to be out of specification.

For example, during the course of testing, we have seen lead levels exceed the BCC’s allowable limit of 0.5 ppm in resin from plastic vape cartridges. An investigation determined that the plastic used to make the vape cartridge was the source of the excessive lead levels. Even if a concentrate passes the limits at the time of sampling, the concern is that over time, the lead leached from the plastic into the resin, increasing the concentration of heavy metals to unsafe levels.

Getting a Representative Sample

The ability to detect trace levels of heavy metals is based on the sample size and how well the sample represents the entire batch. The current California recommended amount of sample is 1 gram of product per batch.  Batch sizes can vary but cannot be larger than 50 pounds of flower. There is no upper limit to the batch sizes for other inhalable cannabis products (Category II).

It is entirely likely that two different 1 gram samples of flower can have two different results for heavy metals because of how small a sample is collected compared to an entire batch. In addition, has the entire plant evenly collected and concentrated the heavy metals into every square inch of it’s leaves? No, probably not. In fact, preliminary research in leafy greens shows that heavy metals are not evenly distributed in a plant. Results from soil testing can also be inconsistent due to clumping or granularity. Heavy metals are not equally distributed within a lot of soil and the one small sample that is taken may not represent the entire batch. That is why it is imperative to take a “random” sample by collecting several smaller samples from different areas of the entire batch, combining them, and taking a 1 g sample from this composite for analysis.

References

California Cannabis CPA. 12/18/2018.  “What to Know About California’s Cannabis Testing Requirements”. https://www.californiacannabiscpa.com/blog/what-to-know-about-californias-cannabis-testing-requirements. Accessed January 10, 2019.

Citterio, S., A. Santagostino, P. Fumagalli, N. Prato, P. Ranalli and S. Sgorbati. 2003.  Heavy metal tolerance and accumulation of Cd, Cr and Ni by Cannabis sativa L.. Plant and Soil 256: 243–252.

Handwerk, B. 2015.  “Modern Marijuana Is Often Laced With Heavy Metals and Fungus.” Smithsonian.com. https://www.smithsonianmag.com/science-nature/modern-marijuana-more-potent-often-laced-heavy-metals-and-fungus-180954696/

Linger, P.  J. Mussig, H. Fischer, J. Kobert. 2002.  Industrial hemp (Cannabis sativa L.) growing on heavy metal contaminated soil: fibre quality and phytoremediation potential. Ind. Crops Prod. 11, 73–84.

McPartland, J. and K. J McKernan. 2017.  “Contaminants of Concern in Cannabis: Microbes, Heavy Metals and Pesticides”.  In: S. Chandra et al. (Eds.) Cannabis sativa L. – Botany and Biotechnology.  Springer International Publishing AG. P. 466-467.  https://www.researchgate.net/publication/318020615_Contaminants_of_Concern_in_Cannabis_Microbes_Heavy_Metals_and_Pesticides.  Accessed January 10, 2019.

Sidhu, G.P.S.  2016.  Heavy metal toxicity in soils: sources, remediation technologies and challenges.   Adv Plants AgricRes. 5(1):445‒446.

Steep Hill, ACCL Find Pesticides in Over 50% of Cannabis Samples

By Aaron G. Biros
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On Election Day, voters in California passed Proposition 64, establishing a recreational cannabis market and regulatory environment. While the state won’t issue the first licenses under the new regulatory scheme until 2018, the medical cannabis industry is already well established.

Steep Hill Labs, Inc., based in Berkeley, California, found in October that 84.3% of samples submitted tested positive for pesticide residue, according to a press release. The announcement came before Election Day, but is particularly eye opening given the massive new market created overnight by Prop 64.rsz_steephill_lab_images_25_of_415_copy

Particularly concerning is their detection of Myclobutanil, which was found in more than 65% of samples submitted to the lab. According to the press release, when Myclobutanil is heated (i.e. smoked or vaporized), it is converted to Hydrogen Cyanide, which is extraordinarily toxic to humans and can be fatal in higher doses.

Reggie Gaudino, Ph.D., vice president of scientific operations and director of genetics at Steep Hill Laboratories. (photo credit: Preston Gannaway)
Reggie Gaudino, Ph.D. (photo credit: Preston Gannaway)

According to Reggie Gaudino, Ph.D., vice president of science, genetics and intellectual property at Steep Hill, their more recent study shows they detected pesticides in roughly 70% of the samples they received and 50% of those contained Myclobutanil. Gaudino says that up to a third of those samples would have failed under Oregon’s regulatory standards.

If a lab test were failed, it would contain pesticides at or higher than the required action level. Oregon’s action level, or the measured amount of pesticides in a product that the OHA deems potentially dangerous, for Myclobutanil is 0.2 parts-per-million (PPM). Steep Hill’s instrumentation has a method detection limit down to the parts-per-trillion (PPT) level, which is a more precise and smaller amount than Oregon’s action level.

“Those in the cannabis community who feel that all cannabis is safe are not correct given this data – smoking a joint of pesticide-contaminated cannabis could potentially expose the body to lethal chemicals,” says Jmichaele Keller, president and chief executive officer of Steep Hill. “As a community, we need to address this issue immediately and not wait until 2018.”

Potentially harmful pesticides, and specifically Myclobutanil, have been detected in Colorado and Washington’s recreational markets on a number of occasions, proving this is a widespread issue. Steep Hill’s release suggests that California regulators take a look at Oregon’s pesticide regulations for guidance when developing the regulatory framework.

What’s even more troubling is that not all laboratories have or had the capability of detecting pesticides at sufficiently low levels and because of this, other labs had significantly lower rates of pesticide detection, suggesting possible inconsistencies in testing methods, instrumentation, sample preparation or other variations. During a 30-day period in late September and early October, Steep Hill found, using publicly available data, or data from contracted testing, that other labs were only reporting between 3% and 21% pesticide detection.

Examination of cannabis prior to testing- credit Steep Hill Labs, Inc.
Examination of cannabis prior to testing- credit Steep Hill Labs, Inc.

It is important to note that those samples were not identical and there could be a great degree in variation on the quality of samples sent to different laboratories, so it is not an entirely accurate comparison. Steep Hill does however detect pesticides down to the parts-per-trillion level, whereas many common methods for detecting pesticides look at the parts-per-billion level.

Reggie Gaudino says the Association of Commercial Cannabis Laboratories (ACCL) is using this data to work with Steep Hill and a number of other labs to address these issues. “As a member of the ACCL, and after discussion with ACCL, we have agreed that all future discussion of this issue should not include laboratory names, as this is about educating the industry in general, and making sure all members of the ACCL are developing the best possible methods for detecting pesticides,” says Gaudino. “The ACCL has responded to this data, by inquiring on a larger, industry-wide basis, which represents a better picture of the issue, rather than only in California’s still-technically unregulated market.” The important message is this is a major issue that needs addressing urgently. “As such, the troubling issue remains, across the larger ACCL membership, there is still detection of pesticides in at least 50% of the cannabis being tested.”

ACCL logoAccording to Jeffrey Raber, Ph.D., president of the ACCL, the industry is experiencing a pesticide problem, but it is very difficult to quantify. “It is fair to say that around 50% of the cannabis being tested contains pesticides, but we really don’t know that exact number until a much more comprehensive statistical analysis is performed,” says Raber. “We agree this is a big problem and that it needs to be addressed, but we are not sure just how big of a problem it really is.” With so much variation in labs in a state where not everyone is required to test products, it is very difficult to pin down how consistent lab results are and how contaminated the cannabis really is. “If all of the labs had the same methodology, samples and shared statistical analyses for a real study then we can look at it closely but it seems we are a ways off from that. I can say confidently however that this is a pretty significant problem that needs addressing.”

Still, Steep Hill detecting pesticides in a majority of their samples and some labs finding as little as 3% should raise some eyebrows. “Unfortunately, our recent study discovered that 84.3% of the samples assessed by our triple quadrupole mass spectrometer contained pesticides,” says Keller. “As of today, this tainted product could be sold in most dispensaries throughout the state of California without any way of informing the patients about the risks of pesticide exposure.”

These findings could mean potentially enormous health risks for medical and recreational cannabis consumers alike, unless regulators, labs and growers take quick action to address the problem.