• Sabine Downer

THC Remediation for Hot Hemp

The techniques used in THC remediation facilities can be very secretive. Many companies are working on patenting technology for cannabinoid separation and CBD manufacturing equipment. With an average cost of $1.00 to $1.50 per gram, THC chromatography is also a very profitable market.


THC remediation from CBD can be achieved through a few different methods. One thing is certain- THC removal is an important step in CBD purification. CBD companies are interested in a variety of THC remediation methods from large scale CBD chromatography to simple techniques like using a centrifuge to separate cannabinoids.


The Real Reason for THC Remediation

Hemp plants are known for producing CBD more abundantly than marijuana. The way the cannabis plant’s genes translate into cannabinoids is unique though. Robert Clarke and Mark Merlin (2016) explain that the cannabis genome is such that plants will always produce some amount of THC and CBD. The type of gene that produces THC and CBD is called a codominant gene. Because codominant genes will always express both traits to some degree separating CBD from THC cannot be fully accomplished through plant breeding. However, some CBD hemp strains will reliably produce THC under the 0.3% legal limit.


Codominant genes for color can be seen in the rhododendron flower that expresses both white and red colors. Cannabinoids THC and CBD are also encoded by a codominant gene type. One cannabinoid may be expressed more, but both will always be expressed somewhat. Image by darwin cruz; CC2.0.


Many have started to cultivate hemp for the purpose of extracting CBD and been surprised to find illegal levels of THC in the extract. When hemp or CBD extract tests above the 0.3% THC limit, it is called “hot.” Hot hemp occurs because of the way cannabinoid genetic works. Genes can mutate or express themselves in unexpected ways. If a hemp crop was not grown from good seed there can be unexpected results later on! Likewise, an extract from a borderline crop may turn up unacceptable THC levels because it has become concentrated.


How Do You Purify Crude CBD Oil?

THC removal from CBD is possible through a variety of techniques. Separating THC from CBD via chromatography is becoming a common way to produce THC-free CBD oil.


Overview of CBD Extraction and CBD Purification

  1. Cannabinoids are separated from plant material through extraction using a solvent

  2. Winterization removes fats, chlorophyll, and other undesirable plant compounds

  3. Vacuum pressure is used to recover solvent from the extract

  4. Decarboxylation converts the acidic version of CBD to non-acidic CBD

  5. Impurities are separated from cannabinoids via distillation

  6. CBD crystallization removes CBD from the rest of the distillate, leaving a “mother liquor”

  7. THC remediation eliminates almost all THC from the mother liquor


The Terminology of THC Remediation and CBD Chromatography

THC remediation is a process that involves a lot of chemistry. For those who aren’t extraction scientists, many of these terms may be unfamiliar. Here is an overview of the terminology used in THC remediation and CBD chromatography.


What is Chromatography?

Chromatography separates mixtures using laboratory techniques. There are two “phases” used in chromatography. The “mobile phase” is the fluid that is used to dissolve the mixture that needs to be separated. The “stationary phase” is a material that is held within a structure to capture parts of the mixture.


The different chemical constituents of the mixture travel through the stationary phase at different speeds. Some materials are retained by the stationary phase resulting in a new mixture with target constituents removed. Different chromatography methods and media are used in order to achieve targeted molecular separation.


What is Column Chromatography?

In column chromatography stationary bed is placed within a tube. The liquid stationary phase may fill the whole inside volume of the tube (packed column) or be concentrated on or along the inside tube wall leaving an open path for the mobile phase in the middle part of the tube (open tubular column).


Column Chromatography THC

In THC column chromatography, a mixture of CBD extract and solvent are poured into a column packed with THC remediation media. The material that passes through the column will have purified CBD. The THC will bond to the THC remediation media and be retained within it.


The chromatography column contains a stationary phase. Different parts of a mixture have different retention times. This allows CBD extractors to collect CBD at one time during the separation and THC at another time.


What is Flash Column Chromatography?

A modified version of column chromatography called flash column chromatography. In flash chromatography, the solvent is driven through the column by applying positive pressure. This technique allows separations to be performed faster, sometimes in less than 20 minutes.


There are two ways to perform flash chromatography: normal-phase and reverse-phase.

Normal-Phase

  • Silica filled column

  • Non-polar solvents (hexane or ethyl acetate)

Reversed-Phase

  • Waxy bonded silica column

  • Water, methanol, and ethanol used for solvents

Flash Chromatography THC

Flash chromatography separation of cannabinoids is possible. Reverse-phased flash chromatography is the best flash chromatography THC removal method. Normal-phased chromatography does not provide THC removal. It may be used for effective cannabinoid purification by flash chromatography of CBG.


What is HPLC?

High performance liquid chromatography (HPLC) is an analytical technique. HPLC is used to separate, identify, and quantify components of a mixture. HPLC uses non-polar solvents for its mobile phase.


Forward Phase vs Reverse Phase Chromatography

Solvents have chemical qualities known as “polarities.” The polar or non-polar quality of a solvent can make it stick to other materials. The stationary phase is polar in forward phase chromatography. In reverse phase chromatography it is non-polar (C-18 material usually).


Other Common Chromatography Terms

Analyte: the substance that is needed from the mixture; the substance separated during chromatography; also called the eluite- the solute which has been eluted

Chromatogram: produced using a chromatograph; visual graphing of chromatography that has peaks corresponding to the mixture components

Eluate: also called effluent; the mobile phase that leaves the column

Eluent: analyte-carrying solvent


The THC molecule takes longer to pass through the stationary phase of the chromatography column. Separating CBD from THC is possible because of the different chemical structures of cannabinoids.


Mobile Phase: chromatography phase that moves in one direction; liquids are used for Liquid Chromatography (LC), gas is used for Gas Chromatography (GC), or supercritical fluid for Super-Critical Fluid Chromatography (SFC)

Solute: sample mixture components

Solvent: a substance that makes other substances soluble

Stationary Phase: silica or other material that is fixed in place during chromatography; other types include bonded stationary phases and immobilized phases; broadly refers to the chromatography column


THC Remediation Methods

THC removal from CBD is accomplished by separating CBD from THC using column chromatography. THC and CBD have very similar boiling points which can make them a challenge to separate. This makes chromatography the go-to method for THC remediation.



Cannabinoid Chromatography Methods for THC Remediation

  • Reverse Phase Chromatography

  • Centrifugal Partition Chromatography

  • Flash Chromatography

Reverse Phase Chromatography THC Remediation

Chemists use reverse phase chromatography for removing THC from CBD distillate that is “hot.” To do this they evaporate the solvent and water from the material. The last step is to send a sample to a third-party lab to test the purity and potency of the CBD distillate. Separating THC from CBD via chromatography creates a THC-free CBD oil that is legal to transport across state lines.


Alternatives to Chromatography for Removing THC from CBD Distillate

THC conversion utilizes chemical conversion, UV light degradation, and/or heat and oxidation to convert THC to CBN. In some cases, it is more economical to convert some THC and CBD to CBN instead of using chromatography.


Spinning band distillation is a method for fractioning cannabinoids. The methods of spinning band distillation are much like short path distillation for CBD. Distillation can yield different results by using different temperatures, solvent amounts, and resins and modifying the distillation set-up.


Spotlight on Cannabinoid Chemistry

THC, CBD, and minor cannabinoids have different polarities and different hydrophobic qualities. The chemical difference between CBD and THC is the number of -OH functional groups on the molecule. This creates a difference in the hydrophobicity (dissolvability in water) of CBD and THC. Similarly, CBD has different polarity than CBG because of slight differences in molecular structure.


Molecular differences allow THC, CBD, and CBDV to be separated through reverse-phase chromatography because it separates molecules by hydrophobicity. Polarity differences allow labs to utilize flash chromatography to separate CBG from CBD and THC.


T-Free CBD Extracts

Pure CBD extract is also called “T-Free extract” or “T-Free distillate.” These products are THC-free and contain 99.9% pure CBD. In order to get T-free, extractors must create isolate by crystallizing CBD or remove THC in some other way.


THC remediation chromatography services are used for removing THC from CBD distillate. These processes convert raw crude to non-detectable THC or compliant CBD distillate or convert CBD distillate into non-detectable CBD oil. Remediation makes CBD purification possible. Ready to sell broad-spectrum oil with 0.3% Delta-9 THC levels or below can be achieved using THC remediation methods.


Types of CBD Extracts

  • Full Spectrum CBD: contains some THC along with terpenes and other non-intoxicating cannabinoids

  • Broad Spectrum CBD: THC-free, pure CBD with terpenes and other non-intoxicating cannabinoids

  • CBD Isolate: THC-free, 99.9% pure CBD


What is Broad-Spectrum CBD Distillate?

Broad-spectrum CBD distillate is more purified than full spectrum CBD distillate. Unlike CBD purification for CBD isolate, broad-spectrum extraction processes retain some non-CBD cannabinoids and terpenes. Reverse Phase Column Chromatography or Centrifugal Partition Chromatography (CPC) are two techniques used to produce broad-spectrum CBD.


What are CBD Isolates? and What are CBD Crystals?

Many are wondering how to isolate CBD. Growing CBD crystals can occur naturally or be achieved by using a CBD isolate machine.


If CBD distillate is over 80% purity, CBD can begin to crystallize a few days after distillation. This distillate also contains cannabinoids other than CBD and terpenes. The resulting crystal slurry is often called “full-spectrum CBD distillate.”


The chemical pentane, or similar hydrocarbon solvents, can also be used to force CBD to crystallize. Crystallizing CBD using hydrocarbon solvents also requires heating and cooling, and sometimes pressure is applied to assist the process.


Washing CBD crystals with cold pentane is one THC removal method that can be used as part of the normal extraction process. However, this method also results in a loss of CBD potency. This is the main method used for producing broad-spectrum CBD distillates that are cheaper than CBD isolate.


What is the difference between isolate and full-spectrum CBD?

CBD isolate is 99.9% pure CBD and does not contain detectable levels of THC. CBD isolate is more widely legal around the world than products that contain detectable THC. Full-spectrum CBD is made by distilling crude CBD extract. Full-spectrum CBD can contain up to 0.3% THC. Unfortunately, the small amounts of THC in full-spectrum CBD can accumulate in the body and result in positive drug test results.



THC Remediation Equipment and THC Remediation Services

THC remediation equipment is ideal for large scale CBD extraction companies. If a CBD producer is generating large amounts of extract, it is most cost-effective for them to perform their own in-house THC remediation.


Since THC remediation equipment can be expensive, some companies use THC remediation services. Not all labs use the same THC remediation techniques. Companies need to be cautious of labs that crash out CBD through crystallization because this practice can result in a less-valuable end product.


When choosing THC remediation services, there are some important questions to ask:

  • Is the facility cGMP compliant and registered with the FDA?

  • What volumes do the facility usually process?

  • What THC remediation methods are being used?

  • What THC remediation equipment is used?

  • What solvents are used in the chromatography process?

  • Is there a choice between compliant (<0.3%) and non-detectable (<0.1%) THC levels?

  • How much loss in volume can be expected?

  • Are there COAs from 3rd-party labs that verify the THC remediation methods?


Final Thoughts on THC Remediation

Federal law requires hemp and hemp-derived products to contain less than 0.3% THC. Some states like Iowa have even more stringent requirements for no detectable THC. From a legal perspective, there is much less risk to companies that are producing THC-free CBD products.


THC-free CBD products are also more accessible to people who work in fields that require drug testing. As mentioned, even small amounts of THC from full-spectrum CBD can accumulate in the body and result in positive drug tests. Truck drivers, government employees, and factory workers are among those that are looking for CBD benefits without the risk of losing their jobs.


THC remediation methods are important tools for the CBD industry. Hemp farmers, CBD extractors, and CBD consumers all benefit from THC remediation. Looking to the future, THC remediation will be an integral processing step for inter-state and international hemp and CBD sales.


References

  1. Clarke, R. C., & Merlin, M. D. (2016). Cannabis domestication, breeding history, present-day genetic diversity, and future prospects. Critical reviews in plant sciences, 35(5-6), 293-327.

  2. National Human Genome Research Institute. (n.d.). Codominance. National Institutes of Health.

  3. Snyder, L. R., Kirkland, J. J., & Dolan, J. W. (2011). Introduction to modern liquid chromatography. John Wiley & Sons.

 

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