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Marijuana Testing and Analysis

Posted June 27th, 2018 by Eric Hopper in

As medicinal and recreational marijuana use becomes more accepted and prevalent throughout the United States, patients and consumers are asking for increased quality control. Medical marijuana patients and customers of dispensaries want to be sure the product they are consuming is not only safe, but is quantifiable in terms of potency. For medical patients, the consistency of the products they consume is very important for appropriate dosing and managing their illnesses. In order to best quantify the sought after cannabinoids and terpenes, many cannabis suppliers are having their products tested and analyzed by certified marijuana testing facilities. Laboratories specializing in marijuana testing and analysis will typically evaluate cannabis products for not only potency, but also for residual solvents, physical and microbial contamination, pesticides and herbicides, heavy metals, and a terpene profile.

Visual Inspection

Upon arrival, a cannabis sample is usually visually inspected with a high-powered dissecting microscope. The initial visual inspection will determine if the sample has any visual signs of molds or other contaminants.

Potency Analysis

Potency analysis is the most recognizable testing done in the cannabis industry. The potency analysis breaks down the prized cannabinoids and details how much of each cannabinoid is present in the sample. Consumers rely on potency testing to make informed decisions regarding the type and proper dosing of medicine to best meet their needs and/or desires. Laboratories commonly perform potency analyses with a high performance liquid chromatograph (HPLC) or a gas chromatograph (GC). A potency analysis is also a valuable tool for growers and extract suppliers. The potency analysis proves consistent results are being achieved in their gardens or extraction operations.

Residual Solvent Analysis

A residual solvent analysis measures the amount of residual solvents remaining in a cannabis extract product. Most labs will express the amount of residual solvents in parts per million (PPM). Solvents are used in cannabis processing to extract a higher potency product from the cannabis flowers and leaves. The active ingredients in cannabis are extracted using solvents such as ethanol, carbon dioxide, butane, etc. After the active ingredients have been extracted, most cannabis processors try to remove as much of the residual solvents as possible from the end product. A residual solvent analysis states the amount of residuals left behind after the supplier’s extraction process. Simply put, the lower the residual solvent, the safer and more pure the extract.

Many medical marijuana patients choose to medicate with a cannabis extract because of its higher potency compared with cannabis leaves or flowers. Medical patients rely on laboratory results to ensure their medicine is safe. Consuming residual solvents can pose health risks to the end consumer. Repeated exposure to some residual solvents can cause health issues, including allergic reactions, headaches, or nausea.

The process typically used to measure residual solvents is a headspace analysis. A headspace analysis involves testing a sample of the gas obtained from the headspace of a sealed vial of the submitted sample. In other words, the extract is housed in a sealed container that has a certain amount of “headspace”, or empty space, left in the sealed container. A gas-tight syringe is used to remove a sample of the air in the headspace which is then tested to determine the PPM of any given solvent. Most often residual solvents are analyzed with a gas chromatograph equipped with a flame ionization detector (FID).

Physical, Microbial, and Mycotoxin Contamination

Any plant matter, cannabis is no exception, is an ideal breeding ground for many types of bacteria and molds. During the harvest and curing processes, contact with people or other physical environmental factors can contaminate the cannabis product. Some mold species are particularly worrisome as they can create particular compounds which are known for causing certain diseases and cancer mycotoxins. Medical patients with compromised immune systems are most susceptible to health issues caused by mycotoxin contamination. Most laboratories rely on a high performance liquid chromatograph (HPLC) and a post column reactor (PCR) to complete a contaminate screening.

Pesticide and Herbicide Analysis

Pesticides and herbicides are used to kill insects, fungi, and bacteria on the cannabis plants during cultivation. Just like solvents, pesticides and herbicides can leave behind residuals that are invisible to the naked eye. When consumed, pesticides and herbicides can pose serious health issues, including liver damage, cancer, and decreased muscle function. Most laboratories that test cannabis will use mass spectrometers (MS) to detect pesticides and/or herbicides on the submitted sample. Mass spectrometers are very sensitive devices that can be used for detecting a large number of pesticides and herbicides.

Heavy Metal Analysis

Heavy metals, such as lead, mercury, cadmium, and arsenic, can cause serious health issues when consumed. Cannabis plants can absorb heavy metals from the soil or hydroponic nutrients in which they are grown. Many laboratories that pride themselves on thorough analyses will include testing the cannabis product for heavy metals. Inductively-coupled plasma mass spectrometry (ICP-MS) and atomic absorption (AA) spectrophotometers are the most reliable instrumentation to test for heavy metals in cannabis samples.

Terpene Profiling

Terpenes are part of a large class of hydrocarbons, which are produced by a wide variety of plant species, including cannabis. Terpenes are referred to as terpenoids when they are denatured by oxidation during the drying or curing processes. Terpenes are a main ingredient of any plant resin or essential oil and are the most significant contributors to a plant’s odor and flavor. Particular terpenes have medicinal value and can enhance the overall quality and potency of a cannabis product. There are over 30 terpenes commonly found in cannabis plants. It is the combination of the different terpenes that contribute to a cannabis plant’s unique attributes. Most laboratories utilize a gas chromatograph (GC) for terpene profiling, although some also implement post column reactor (PCR) machines.

Equipment Used for Cannabis Testing

Laboratories that test cannabis products rely on lab technicians to operate the sophisticated testing equipment. Analytical chemists and extraction technicians work together to obtain the most accurate results from high-tech devices, such as high performance liquid chromatographs (HPLC), gas chromatographs (GC), and mass spectrometers (MS).

High Performance Liquid Chromatograph (HPLC)

High performance liquid chromatography is a technique used in analytical chemistry to separate, identify, and quantify individual components in a mixture. HPLC devices rely on mechanical pumps to pass a pressurized liquid solvent containing a sample mixture through a column filled with a solid adsorbent material. Individual compounds within the sample will interact slightly differently with the adsorbent material, thus causing different flow rates for each component. The different flow rates lead to the separation of the components as they flow out of the column.

Gas Chromatograph (GC)

Gas chromatography is a technique used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. In gas chromatography, there is a mobile phase and a stationary stage. During the mobile phase, or moving phase of gas, helium or nitrogen is typically used as a carrier. The gas is moved through a column, which is generally made of metal or glass. The inner walls of the column are coated with a microscopic layer of a particular liquid or polymer and the gaseous compounds being analyzed then interact with the material on the column walls. This interaction causes the compounds to elute at different times, known as the retention time of the compound. The comparison of retention times is what makes gas chromatography useful for analysis.

Mass Spectrometer (MS)

Mass spectrometry is a technique used for cannabis analysis that ionizes chemical compounds and sorts the ions based on their mass-to-charge ratio. Mass spectrometry allows a laboratory to measure the masses within a sample. Samples analyzed with mass spectrometry can be solid, liquid, or gas.

Medicinal and recreational cannabis consumers rely on laboratory testing to ensure the consistent, safe, and accurate quantization of cannabis products. Cannabis growers and extract suppliers can rely on laboratory tests not only to ensure the safety of their products, but also to differentiate their products from their competitors. Potency testing and terpene profiling are the analyses that most cannabis consumers will use to determine the best medicines or products for their particular needs. Dispensaries rely on laboratory results to ensure the products they sell are safe to consume and free from heavy metals, pesticides, herbicides, and/or residual solvents.

As the laws and the stigmas regarding cannabis continue to change, laboratory-certified products will allow for the quantification necessary to further legitimize cannabis products to the general public. The more a cannabis product can be analyzed for consistent potency and potential contaminates, the more people will accept cannabis as a medicine and safe recreational alternative. Laboratories that employ a knowledgeable staff of analytical chemists and extraction technicians will be at the forefront of accurate testing and quantification. The sophistication of equipment used to scientifically test cannabis for potency and/or contaminates shows just how far the cannabis industry has come. The quality and potency of a cannabis product is no longer a guessing game. Thanks to laboratory testing, cannabis patients and consumers can make informed, safe decisions regarding the cannabis products they wish to consume.

Eric Hopper is a Professional Marijuana Grower Senior Editor.

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