March 12, 2020

WHAT IS THC REMEDIATION? EVERYTHING YOU NEED TO KNOW

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.

THC REMEDIATION AND HEMP PROCESSING

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.

MANUFACTURING COSTS AND EFFICIENCY

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.

THC REMEDIATION AND THE CANNABIS PRODUCTION PROCESS

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!

WHAT IS “CRASHING”?

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:

  1. Better separation of the THC. 
  2. 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.

THE IMPORTANCE OF THE COLUMN IN THC REMEDIATION

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.

POLARITY AND THC REMEDIATION

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:

  1. CBD is more polar. 
  2. 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.

LET’S TALK ABOUT SOLVENTS

As we discussed above, solvents are critical in THC remediation. Now, it’s important to remember that the type of solvents used will greatly influence the degree of separation. Furthermore, a THC remediation process can and should be developed with the specific needs of the operation in mind. In other words, the type and combination of solvent greatly affect the efficacy of the system, although it will vary from operation to operation.

Additionally, there are two general types of chromatography that can be used in THC remediation:

  1. Liquid chromatography (LC)
  2. Gas chromatography (GC)

These are just the general categories – there are multiple types of more specialized methods that can be implemented. However, it’s important to understand this distinction because it matters when it comes to understanding how the solvent is used in the process. In analytical chemistry, the eluant or eluent is the actual “carrier” that “carries” the analyte through the column during the mobile phase. In liquid chromatography, it is a liquid solvent; in gas chromatography, it is a gas acting as the “carrier” (also referred to as a “carrier gas”).

That being said, carbon dioxide (CO2) is most frequently used as the carrier gas in GC. In LC, however, there are a number of different liquid solvents available, including:

  1. Alcohol (ethanol or isopropyl) 
  2. Water (H2O)
  3. Hydrocarbons (usually hexane)
  4. Any number of acetate groups

Furthermore, it’s possible to use a single solvent, although it’s highly inefficient. It’s best to design a system that makes use of multiple solvents in order to make the entire remediation process that much more efficient.

Let’s quickly examine a particularly common solvent combination in THC remediation: water plus alcohol. It’s useful to break this down as follows:

  1. Alcohol is the main solvent. It carries the phytocannabinoids through the column. 
  2. Water is the “modifier”. It modifies the polarity. 

That being said, you can use as many solvents as you like as long as you have the means to recover and/or recycle them at the end of the remediation process. Ultimately, it depends on the setup of the lab in question.

METHODOLOGY IN THC REMEDIATION

As you can see above, the practice of combining water with alcohol for the solvent combination is just one of the ways that an operator could boost the remediation process (or, for that matter, performing crashing before the actual remediation). This is collectively known as methodology and it will make a huge difference in the efficiency and efficacy of your THC separation.

In other words, methodology refers to the variables put in place to get a consistent, desirable, and reproducible result in the chromatography process. That being said, let’s take a look at some of those variables in methodology:

  1. Type of chromatography. Remember, there are multiple systems that can be used for THC remediation – for some details on how to use high-performance liquid chromatography (HPLC), see the next section.
  2. Injection volume. The amount of distillate or mother liquor that you inject into your chromatography system will greatly affect how quickly the remediation is executed. Remember the example cited above that makes the case for crashing being implemented before remediation. Furthermore, the injection volume varies from one chromatography machine to another. 
  3. Rate of flow. This refers to how quick the analyte is carried by the solvent (or carrier gas, in cases of GC being used). 
  4. Composition of carrier. Remember, we mentioned a setup where you can combine water with alcohol. This is far from the only potential composition and there are a number of different ones you can use. Ultimately, you just have to ensure that you have a way to reclaim and recycle the multiple solvents. 
  5. Pressure in the system. This is important in nearly every part of physical/analytical chemistry. However, in this context specifically, A higher pressure will result in greater crystallization of CBD. 
  6. Rate of change of solvent. This is related to the rate of flow. 
  7. Collection method (or “separating the fractions”). You’ll have to actually determine how frequently to collect the final distillate being carried through the column in order to determine its chemical makeup. In other words, you’ll need to collect at regular intervals of time in order to determine when your analyte of interest (in this case, THC) is carried out of the column. 

These variables will all affect how the chromatography process works and the amount of time it takes for the analyte to be carried through the column.

HPLC CHROMATOGRAPHY AND THC REMEDIATION

As stated above, there are a number of different forms of chromatography that can be used. However, high-performance liquid chromatography (HPLC) is exceptionally effective and efficient, particularly a form of HPLC known as flash chromatography (or reverse-flash chromatography, depending on the polarity within the column).

So why are HPLC/flash chromatography systems so popular for THC remediation?

  1. They have exceptionally large pumps, especially when compared to other columns. 
  2. An operator can make a much higher injection volume (thereby speeding up the THC remediation process). 
  3. They operate with a solid-state column. 

That’s not to say that these systems are the only ones being used. For example, both centrifugal partition chromatography (CPC) and counter-current chromatography (CCC) are forms of LC that are used frequently in THC remediation, although they generally do not have solid-state columns.

READING A CHROMATOGRAPH TO SEPARATE THE FRACTIONS

So now let’s assume that you’ve created your THC remediation system. You’ve determined how your methodology will work and what kind of chromatographic system you’ll be using to execute the actual remediation. Let’s even assume that you’ve decided to go with crashing as the first step in order to create a mother liquor which you’ll then inject into your column. Great! But how do you actually know when the THC is being separated out?

Remember, THC remediation is all about time. In other words, the amount of time it takes a chemical component to be carried through the column will tell you what that actual component is. The only way to properly parse this data, with sufficient granularity to create an effective remediation process, is with the use of a chromatograph.

This is a visual representation that will present as a series of minima and maxima (“peaks” and “valleys”) over a function of time. If you’ve designed your chromatography method properly, the THC will stay in the column longer (remember, it has lower polarity). When examining your chromatograph, you’ll want to look for maxima (or THC peaks) as the interval of time when the THC is being carried through the column.

In other words, by collecting at regular intervals of time, you can effectively separate the fractions so that your THC is separated from your CBD (and other phytocannabinoids). Of course, you’ll have to do a quantitative analysis of the distillate you remove from the column using either GC or LC.

Additionally, you’ll want to recover the liquid solvent you used via some sort of solvent recovery system. This is most frequently done with a rotary evaporator (roto-vap) or a falling film evaporator. Solvent recovery is a crucial part of keeping the return on investment (ROI) high and ensuring that profit margins stay healthy.

THC REMEDIATION IS THE FUTURE

There is a sizable contingent in the cannabis industry who see THC remediation as critical in hemp processing and the future of manufacturing cannabis products. Furthermore, it’s especially important in areas where there are strict laws in place limiting the amount of THC that can be present in a given cannabis product. However, any lab looking to implement THC remediation will have to take the time to develop its methodology, including choosing the type of chromatography as well as the solvent combination and chemical makeup of the column.

Furthermore, the importance of efficiency and high yield can not be overstated. Besides, anyone can purchase the equipment and solvents and run the process. The real questions are:

  • Are they being efficient? 
  • Are they maximizing the yield from their biomass? 
  • Will they be able to effectively monitor and remediate the THC?

This is where Capna Systems comes in! What we bring over all others is a low cost of manufacturing for THC remediation. Plus, we are always working diligently on innovating in industrial hemp extraction. Furthermore, a producer could easily use our kit for supercooled ethanol extraction as well as our solvent recovery setup in order to integrate it with a THC remediation process. If you’d like to learn more, be sure you book a demo or give us a call today!

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