THC remediation is the process of removing THC from a cannabis distillate. Although there are numerous techniques available, using some form of chromatography is the most common.

Although Federal Law has made it legal to use industrial hemp extraction to create cannabis products, the THC content can be no higher than 0.3%. Of course, in some states THC is legal recreationally and/or medicinally, but all processors need to monitor and remediate the THC when cultivating and processing industrial hemp. This is because the licenses required for growing hemp are contingent on keeping the THC levels below the federally mandated 0.3%, otherwise, processors must go through the more stringent application and approval to grow marijuana (as opposed to just hemp).

In other words, it’s absolutely vital to always monitor and remediate THC levels for any hemp processing operation.

Obviously, if you’re extracting cannabis oil and making its concentration greater, then the relative volume of THC will increase. This can happen with both crude or distillate, and hemp oil that has THC levels above the federally mandated 0.3% is sometimes referred to as “hot”. So how do cannabis processors ensure that products have little to no THC? How do they make sure that they’re not processing “hot” distillates? Well, the answer is simple: they use THC remediation!

THC remediation could also be referred to as the resolution (or separation) of THC from hemp oil (or CBD oil). For the purposes of this article, we’ll talk about separating THC from CBD, but in reality, you’re actually separating the THC from all the other phytocannabinoids. Remember, cannabis has a whole host of these beneficial compounds (as well as other chemical components), and most cannabis processors prefer to keep the other phytocannabinoids intact along with the CBD in order to give their products a boost in efficacy from the entourage effect.

Not only is it a legal necessity to monitor and remediate THC, but it also helps increase efficiency and yield. The resolution of THC and CBD is virtually impossible to achieve with 100% efficiency, but the higher the efficiency, the greater the final yield will be.

Additionally, let’s take a moment to consider manufacturing costs. There are various factors that can greatly affect these costs, including:

Cost of solvents (depending on the type of extraction being used – ethanol, hydrocarbon, or carbon dioxide).
The efficiency of the method.
Assuming that these factors and variables are properly controlled and accounted for, then the typical cost of manufacturing is $.35 to $.55 per gram. However, if a processor is running a low-yield and inefficient method, then those manufacturing costs can easily increase. This can eat away at profit margins and damage the financial viability of any operation. That being said, THC remediation keeps the entire cannabis production process more efficient.

So where does THC remediation fall within the general cannabis production process? Well, you can break down the major steps as follows:

Extraction → Distillation → Crashing → Chromatography (THC Remediation)

As you can see, you obviously start with extraction from the biomass. There are a number of different types of cannabis extraction, each with their respective pros and cons. Following that, there are also a number of different forms of distillation. However, there is another process known as crashing that is frequently used before THC remediation. The result of this step is a syrupy, THC-rich liquid known as mother liquor – it is essentially a THC distillate that has had most of its CBD precipitated out in the form of crystals. So, let’s start there!

In order to have a THC remediation that’s efficient after extraction and distillation, it’s generally best, to begin with crashing. This process starts with taking the distillate and precipitating the CBD out in the form of crystals. Some technicians will also refer to this as collapsing mass – in essence, you are increasing the THC content before you actually pull it out in the process of remediation. As a result, it’s usually performed in a piece of kit known as a crystallization vessel or crystallization reactor.

So why is it generally better to perform crashing before remediation? Well, it results in:

Better separation of the THC.
Higher yield of the THC remediation.
Remember, the whole point of THC remediation is to pull out as much of the THC as possible. In fact, if it’s properly executed, then a technician can achieve remediation of 99.9%. Furthermore, performing crashing first also helps with mass action transfer in order to more fully achieve this THC separation.

Let’s take a look at an example. Say you’ve performed your extraction and distillation and now have 1000 grams of distillate. Now, let’s also say you have a chromatography process that you’ve set up that can remediate 250 grams every 48 minutes (this is a fairly typical timeline). That means it will take you 2.8 hours to perform THC remediation on the full 1000 grams.

Instead, consider that you’ve performed crashing first and you are left with 750 grams of precipitate (crystallized CBD) and 250 grams of mother liquor (this is the syrupy, THC-rich liquid you end up with after crashing). Of course, you set aside that crystallized CBD and you’ll only have to inject the 250 grams of mother liquor into your chromatography setup. As a result, you’ll be able to execute the THC remediation on the mother liquor in 48 minutes as opposed to 2.8 hours on the entire distillate.

In other words, crashing just helps make the process that much more efficient and effective.

OK, so let’s say that you’ve gone through the process of crashing. You now have your mother liquor that is ready to go through the process of THC remediation. As mentioned earlier, this is most frequently done via chromatography. But why is that? Well, because the boiling points of CBD and THC are so close, it’s difficult to perform resolution using molecular distillation. This is where the chromatography comes in!

That being said, the efficacy of the chromatography process is primarily contingent on the fact that the THC and CBD are separated based on their interactions within the fractionalizing column. It’s important to remember that when we talk about CBD in this context, we’re including all the other phytocannabinoids that aren’t THC. Furthermore, the process of moving these components through the column is known in chromatography as the mobile phase.

What does all this mean, exactly? First of all, the column is really the most fundamental piece of kit in the entire remediation process. Remember, multiple forms of chromatography can be used, but the actual THC/CBD separation has to occur within the column. This process of physical separation occurs by slowing down certain chemical components while speeding up other chemical components. As a result, the different components (in this case THC and CBD/other cannabinoids) then exit the column at different times, allowing the technician to collect the separated components at the end.

How does the column affect these rates? Well, first of all, there is the presence of a solvent (or, more usually, multiple solvents). Additionally, the column itself can consist of a number of different compounds. Most frequently, however, it is some combination of phenyl groups, depending on the needs of the lab in question. For example, when choosing what column to use, your technician will have to examine the structure of the molecule to find what works best.

The most common chemical makeup of these columns is some variation of a carbon chain with 18 carbons (C18), also known as a C18 column. Most frequently, these C18 columns are paired with some form of silica in order to create the necessary environment to “carry” certain chemical components out at different times. As a result, this brings us to the next important concept: polarity.

This combination of solvent plus the phenyl chains (or C18 ) in the column exploits the topological polarity of the various chemical components. The polarity of large, organic compounds can vary from one part of the structure to another. Let’s take a look at THC, for example: it is primarily made up of hydrogen and carbon (both of which have similar electronegativity). The “backbone” of the compound, so to speak, is a long nonpolar carbon chain attached to a benzene ring. It also has a few other carbon rings with attached methyl groups that are also largely nonpolar.

However, let’s not forget that THC also has two oxygen with higher electronegativity – it is at these points in the structure where the slight polarity gives THC very limited water solubility. Now, the same is true for CBD, but its polarity is significantly higher. This means that although THC and CBD both have limited solubility in water, CBD has a greater solubility in water.

Now, let’s consider how topological polarity affects the process of THC remediation. Remember that both THC and CBD have the same chemical formula (C21H30O2) – the crucial difference is in the actual structure of the compounds. That being said, the pyran ring is closed on THC but open on CBD. This means that:

CBD is more polar.
THC is less polar.
Consequently, the CBD moves more with the solvent while the THC moves more with the column. It’s also important to remember that in this context, the chemical component moving through the column is known formally as an analyte. Part of the process of THC remediation is determining when the THC analyte is moving through the column so that you can ultimately separate it out.

Now, because THC has a lower polarity, it is carried more by the column and will, therefore, stay in the column longer! However, it’s not only the column that affects this process – solvents are also a crucial component.

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