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Decarboxylation: A Beginner’s Guide

Despite its growing popularity, the general public still has lots to learn about marijuana. For example, few understand the chemical reasons why cannabis has to be heated – or decarboxylated – before consumption.

Let’s just say that if you were to consume a bag of raw weed, the effects would be very minimal. Decarboxylation converts the major phytocannabinoids in cannabis (THC and CBD) into active molecular forms that can influence our bodies’ neurotransmitters. In fact, without decarboxylation, marijuana would possess few – if any – of its medical and recreational properties.

Decarboxylation: A Requisite Chemical Reaction for Cannabis Edibles, Oils, and More

When you heat cannabis, you help activate the compounds contained within it. For example, if you decide to make edibles with marijuana, the flowers need to be decarboxylated first.

If you fail to decarb your weed, you’re doing little more than adding raw plant matter. As nutritious as raw cannabis is, it does little in terms of producing therapeutic benefits.

Raw Cannabis vs. Decarboxylated Cannabis

Raw cannabis is plant matter that has not been dried or cured. Once cured, a small amount of decarboxylation occurs. The rest takes place when the plant material is heated – or combusted – to temperatures above 200 degrees Fahrenheit.

However, marijuana still has beneficial uses in its raw, uncured form. Before curing and decarboxylation, THC and CBD – the two most active cannabis compounds – exist as acids (THC-A and CBD-A). These acids possess anti-inflammatory effects, similar to vitamins and minerals found in other plant-based foods.

DID YOU KNOW? Eating raw cannabis has many nutritional health benefits?

If you consume raw cannabis, use either the fan leaves or flowers that have been freshly-picked. Raw marijuana can be stored in your refrigerator just as long as other greens like kale or spinach. However, it is essential to monitor your raw cannabis because it is prone to wilting and mold. This is particularly true for densely-packed flowers that contain a high moisture content.

If left undisturbed, the active compounds in cannabis will decarboxylate over time. However, total decarboxylation of THC-A and CBD-A in raw plant material would take years. When exposed to heat, the compounds decarboxylate instantaneously.

What Is Decarboxylation?

Even though raw (carboxylated) cannabis possesses nutritional benefits, it is entirely non-intoxicating. In other words, it will not produce a high. To get the full effects of marijuana, it has to be heated – or decarboxylated.

As we mentioned above, the process of drying and curing can release a small number of psychoactive compounds. However, this pales in comparison to the number of cannabinoids released during decarboxylation.

The term decarboxylation refers to the chemical reaction that removes a carboxyl (COOH) group from THC-A and CBD-A. Carbon dioxide is released as a by-product of this reaction. To decarboxylate marijuana, all you have to do is apply heat. But how much heat is necessary? Or in other words, at what temperature does marijuana decarboxylate?

We will answer this question later in the article. First, let’s take a look at some of the other advantages of decarboxylation. That is apart from the fact that it produces chemically-active forms of phytocannabinoids.

Advantages of Decarboxylation

One of the most common mistakes people make when making edibles from marijuana is failing to decarb their cannabis. Unless you’ll be baking your edibles (pot brownies, cookies, etc.) before consumption, it is necessary to use an oven to heat the plant material and release the activated THC and CBD.

Give your cooking an extra kic…

Incidentally, when you decarb weed for edibles, you also reduce the risk of botulism. When you don’t go through the process correctly, botulinum bacteria can quickly grow in things like cannabutter and canna-oil.

Of course, every time you light up a joint or vaporize your weed, you are automatically decarbing it. In the absence of its carboxyl group, tetrahydrocannabinol (THC) can bind to the body’s cell receptors. But what about cannabidiol – does CBD need to be decarboxylated?

Why You Need to Decarboxylate CBD Strains

You may think that CBD decarboxylation is unnecessary. After all, why would you need to decarb a strain that’s already non-intoxicating?

In reality, the same decarboxylation rules apply to CBD as they do to THC. Because raw cannabis contains the acid form of CBD (CBD-A), CBD strains must be heated to release their active properties. Like THC-A, CBD-A has its health properties. It’s believed that if you consume CBD-A, your body will metabolize it and break it down into CBD on its own.

Decarboxylation of CBD increases its bioavailability, making more of it available to the body’s cells.

However, cells need to work harder to break down CBD’s carboxyl component. Moreover, much of the active compound is lost as heat during the exothermic reaction. In other words, having your body decarb CBD on its own would be extremely inefficient.

Exposing the plant material to sufficient heat decarboxylates CBD instantaneously, as described above. Products like CBD oils or CBD gummies, however, have already been decarboxylated. This is why you can consume them in their natural state, without having to heat them.

How to Decarboxylate Weed

Aside from smoking or vaping, there are many ways to decarboxylate weed and gain its therapeutic and recreational effects. We’re going to show you the most basic one. You’ll need the following equipment:

  • An oven
  • A baking sheet
  • Parchment paper
  • Cannabis flower (trim, nugs, kief, etc.)

If you elect to use nugs, grind them coarsely before following these steps. In the following example, we used 40 grams of flower to produce coconut canna-oil.

Step 1: Preheat the oven:

Set the oven to 235 degrees Fahrenheit (120 degrees Celsius). Place the parchment paper on the baking sheet, and spread your marijuana flower across it. Make sure to break up larger pieces with your hands if necessary.

Step 2: Bake for approximately 40 minutes:

This should be a sufficient amount of time for well-dried weed. However, please note that if you’re using fresher marijuana with more moisture, it could take up to 90 minutes.

Some users invest in a hygrometer to check the level of moisture in their herb. It is easy to use; place the weed in a closed container with the hygrometer. After the weed is dry enough, leave it to completely cool.

Step 3: Remove and let cool:

After 30 minutes, remove the baking sheet from the oven and let it cool down. The decarboxylation process is now complete, and the majority of THC-A and CBD-A should be converted into THC and CBD.

Decarboxylation Temperature for THC and CBD

If you ask twenty different cannabis users what temperature they decarb their weed at, you’ll likely get twenty different answers. We can tell you that the lower the decarboxylation temperature, the longer the chemical process takes. But few people realize that if decarboxylation temperatures are too high for too long, you risk ruining the herb’s active ingredients.

There is a dispute over the exact decarboxylation temperature of CBD. According to studies, it appears to be approximately 230 degrees Fahrenheit (110 degrees Celsius).

As for the timeframe, neither THC nor CBD will decarboxylate instantaneously at their precise decarb temperatures. A more extended period – typically between 40 and 60 minutes – is required for the COOH group to break down into water and carbon dioxide.

Also, be advised that the boiling points of cannabinoids, terpenes, and flavonoids are much different than their decarboxylation points. Boiling points for these compounds have been much more thoroughly studied than their decarb temperatures:

Cannabinoids

  • CBC:428 degrees Fahrenheit/220 degrees Celsius
  • THC:314 degrees Fahrenheit/157 degrees Celsius
  • CBN:365 degrees Fahrenheit/185 degrees Celsius
  • THCV:428 degrees Fahrenheit/220 degrees Celsius

Terpenes

  • Myrcene:330-334 degrees Fahrenheit / 165-168 degrees Celsius
  • Limonene:150 degrees Fahrenheit/177 degrees Celsius
  • Linalool:388 degrees Fahrenheit/198 degrees Celsius
  • Alpha-pinene:312 degrees Fahrenheit/156 degrees Celsius

Flavonoids and Phytosterols

  • Beta-Sitosterol:273 degrees Fahrenheit/134 degrees Celsius
  • Cannflavin A:359 degrees Fahrenheit/182 degrees Celsius
  • Apigenin:352 degrees Fahrenheit/178 degrees Celsius
  • Quercetin:482 degrees Fahrenheit/250 degrees Celsius

It is advisable to keep your decarboxylation temperatures on the low side to preserve terpenes. Some compounds are volatile and evaporate at higher temperatures. The result is foul odors and an unpleasant taste. To preserve the terpenes, try and keep the temperature in the 200-300 degree Fahrenheit range.

Now that we know the key to faster decarboxylation is greater heat (within reason), it should be a straightforward process. Unfortunately, it isn’t quite as easy as that. The existence of another mechanism means we have to control decarboxylation temperatures very carefully.

When we heat cannabis and turn THC-A into THC or CBD-A into CBD, we convert THC to CBN faster. Once we reach 70% decarb, THC gets converted into CBN faster than the conversion of THCA into THC. In other words, when we go beyond 70% decarboxylation, THC levels start to fall off quickly. See the above chart for reference.

As helpful as graphs are, there is always an issue with the interpretation of data. For instance, the graph above relates to marijuana extract data. The temperatures used for kief, bud, or trim would be different. The graph was created in 1990 and involved decarbing a hexane extract in an open container on a hot plate. With modern equipment, it is possible to reach a 100% decarb without damaging your THC content.

Compound Before Decarb 30 Min Decarb 60 Min Decarb
THCA 24.5% 2.6% 0.1%
THC 3.8% 25.4% 25.5%
CBDA 0.6% 0.3% 0.3%
CBD 0% 1% 0.1%
CBN 0.4% 1% 1.4%
Moisture 0% 0% 0%
Total Cannabinoids 29.3% 30.3% 27.4%

Cannabis Trim

Compound Before Decarb 30 Min Decarb 60 Min Decarb
THCA 6.5% 2.9% 0.2%
THC 0.6% 4.8% 6.9%
CBDA 0.2% 0.2% 0.1%
CBD 0% 0% 0.1%
CBN 0% 0% 0%
Moisture 3.4% 4.5% 0%
Total Cannabinoids 7.3% 7.9% 7.3%

Marijuana Growers HQ’s efforts went some way towards solving the mystery of the best decarbing temperature. In 2012, they tested cannabis trim and kief at 240 degrees for 30 and 60 minutes. The above table outlines the results.

They discovered that the vapor point of all significant terpenes, flavonoids, and cannabinoids was right around 246.2 degrees during their research. As consumer-grade ovens are not that reliable when reading temperatures, they played it safe by staying a few degrees below at 240 degrees.

According to the results, 30 minutes was not long enough to completely decarb the trim or the kief. The latter had reached 90%, but the former only managed 60%. Both were very close to 100% after an hour.

Decarboxylation Methods Investigated

Most assume that the oven is the best way to decarb, but is this really the case? Bear in mind that most ovens will fluctuate by 10 degrees in either direction. When using the oven in the 250-400-degree range in particular, if the heat is 10-15 degrees more than what you’ve set, the result could mean the loss of essential compounds.

DID YOU KNOW? You could lose up to 33% of your THC via oven decarboxylation.

The crockpot/water bath method is a popular one because water boils at a very consistent temperature of 212 degrees (depending on altitude). While the max temp will preserve all compounds, the problem with this method is it’s impossible to achieve full decarboxylation.

This is because decarboxylation is not a linear process, as the last part of the THC-A to THC conversion process takes longer. When you use boiling water, the weed is exposed to heat for too long, causing degradation.

A product on the market called “Nova” claims to decarb cannabinoids with 100% efficiency. It provides lab tests to back up this claim. Therefore, it may be worth checking out if you’re dedicated to keeping the potency of your cannabis intact.

The other issue with decarb charts or graphs is a lack of knowledge of the precise starting point of the decarb process. In other words, the times and temperature figures shown are always the averages. Remember, you can’t place dry material in an oven and expect it to remain at that exact level for the duration of the decarbing process.

How to Decarboxylate Kief

Kief is the name given to the crystallized structures that stick to the surface of pure cannabis. It is essentially cannabis dust that acts as a defense mechanism to keep pests away. Kief is a popular by-product of cannabis consumption used for edible creation.

Everything you’ll ever need to…

If you decide to try kief decarboxylation, grind the cannabis into flakes and sift the kief away from the plant parts.

Kief tends to decarb faster than bud, meaning you can afford to employ a lower temperature. Once you have spread it over the baking sheet, follow the steps mentioned above. Place the kief on a parchment sheet, and put it in the oven between 240 and 300 degrees Fahrenheit (115 – 150 degrees Celsius). It should be fully decarboxylated after 45-60 minutes.

Final Thoughts on Decarboxylation

Decarboxylation is one of the least understood aspects of marijuana parlance. To fully benefit from cannabis, most of the active components first need to be decarboxylated. THC-A must be transformed into THC, CBD-A into CBD, and so on.

When you combust cannabis or use a vaporizer, the process of decarboxylation occurs instantly. However, those who prepare edibles have to go through a time-consuming decarb process to ensure their products are “molecularly active.”

Although there is some merit to consuming raw cannabis, it offers few therapeutic (or recreational) benefits compared to the decarbed version.

Want to learn more? Decarboxylation is extremely important, but so is knowing how to dry and cure your harvested marijuana flower. Learn how to do it properly in our Complete Guide to Drying and Curing Cannabis Buds.

What is Decarboxylation? Despite its growing popularity, there are still a few basic cannabis facts that people don’t understand. Here we explain…

Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array-Mass Spectrometry

Mei Wang

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

Yan-Hong Wang

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

Bharathi Avula

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

Mohamed M. Radwan

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

Amira S. Wanas

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

John van Antwerp

2 Waters Corporation, Milford, Massachusetts.

Jon F. Parcher

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

Mahmoud A. ElSohly

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

3 Department of Pharmaceutics and Drug Delivery, School of Pharmacy, University of Mississippi, University, Mississippi.

Ikhlas A. Khan

1 National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi.

4 Division of Pharmacognosy, Department of BioMolecular Science, School of Pharmacy, University of Mississippi, University, Mississippi.

Associated Data

Abstract

Introduction: Decarboxylation is an important step for efficient production of the major active components in cannabis, for example, Δ 9 -tetrahydrocannabinol (Δ 9 -THC), cannabidiol (CBD), and cannabigerol (CBG). These cannabinoids do not occur in significant concentrations in cannabis but can be formed by decarboxylation of their corresponding acids, the predominant cannabinoids in the plant. Study of the kinetics of decarboxylation is of importance for phytocannabinoid isolation and dosage formulation for medical use. Efficient analytical methods are essential for simultaneous detection of both neutral and acidic cannabinoids.

Methods: C. sativa extracts were used for the studies. Decarboxylation conditions were examined at 80°C, 95°C, 110°C, 130°C, and 145°C for different times up to 60 min in a vacuum oven. An ultra-high performance supercritical fluid chromatography/photodiode array-mass spectrometry (UHPSFC/PDA-MS) method was used for the analysis of acidic and neutral cannabinoids before and after decarboxylation.

Results: Decarboxylation at different temperatures displayed an exponential relationship between concentration and time indicating a first-order or pseudo-first-order reaction. The rate constants for Δ 9 -tetrahydrocannabinolic acid-A (THCA-A) were twice those of the cannabidiolic acid (CBDA) and cannabigerolic acid (CBGA). Decarboxylation of THCA-A was forthright with no side reactions or by-products. Decarboxylation of CBDA and CBGA was not as straightforward due to the unexplained loss of reactants or products.

Conclusion: The reported UHPSFC/PDA-MS method provided consistent and sensitive analysis of phytocannabinoids and their decarboxylation products and degradants. The rate of change of acidic cannabinoid concentrations over time allowed for determination of rate constants. Variations of rate constants with temperature yielded values for reaction energy.

Introduction

The plant Cannabis sativa, in the form of crude drugs, marijuana, hashish, or hash oil, is the most widely consumed and popular recreational/medicinal botanical drug product in the world. 1 The legal status of cannabis varies significantly from state to state within the United States and also from country to country. As a result of the rampant use and confounding legal issues, there has been a significant case load increase seen in forensic laboratories. Therefore, cannabis is now one of the most thoroughly studied and analyzed plant materials. More than 100 cannabinoids have been isolated and identified in cannabis 2 along with the primary psychoactive component, Δ 9 -tetrahydrocannabinol (Δ 9 -THC). In addition to Δ 9 -THC, there are other components of cannabis that have been shown to be medically beneficial. For example, cannabidiol (CBD) and cannabigerol (CBG) can moderate or influence the psychoactive effects of Δ 9 -THC. 3,4 Studies of cannabis have also investigated the potential benefits of phytocannabinoids as anticancer, antiemetic, sedative, and palliative agents for several other disease states and symptoms. 3,5

Efficient production of Δ 9 -THC, CBD, and CBG from cannabis is important for the development of dosage formulations to facilitate the successful medical use of cannabis. These neutral cannabinoids do not occur at significant concentrations in the plants. Cannabis synthesize primarily the carboxylic acid forms of Δ 9 -THC, CBD, and CBG, namely, Δ 9 -tetrahydrocannabinolic acid A (THCA-A), cannabidiolic acid (CBDA), and cannabigerolic acid (CBGA). These acidic cannabinoids are thermally unstable and can be decarboxylated when exposed to light or heat via smoking, baking, or refluxing. As a result, the requisite forensic analyses are usually expressed as the sum of the acidic and neutral forms of the cannabinoids. Reports also show that Δ 9 -THC itself readily oxidizes to cannabinol (CBN) with oxygen and light during the decarboxylation process. 6

To understand the decarboxylation reactions that can occur with phytocannabinoids, efficient analytical methods are necessary to determine the concentration variations of decarboxylation reactants (acidic cannabinoids) and products (neutral cannabinoids) over time. Many analytical instruments have been applied to analyze cannabinoids in cannabis. 3,6,7 Among them, gas chromatography (GC) and liquid chromatography (LC) are the most commonly used techniques.

GC is ideal in some ways for these low molecular weight (280–360) neutral cannabinoids. However, the labile acids cannot be analyzed by GC without decarboxylation or derivatization. 8 Hewavitharana et al. 9 reported the decarboxylation reaction conducted in a heated GC injection port and suggested that this process can provide a means of complete conversion of the acids to neutral cannabinoids. Likewise, Dussy et al. 6 also studied the decarboxylation of pure Δ 9 -tetrahydrocannabinolic acid A (THCA-A), however, the generation of Δ 9 -THC was maximal at an intermediate temperature (225°C) but with only 65% conversion. At 300°C, a significant loss of Δ 9 -THC was observed, although no CBN, a possible oxidation product, was observed. Thus, the use of a GC injection port to convert THCA-A to Δ 9 -THC was not satisfactory under the experimental conditions of that particular study. In summary, GC analyses are complicated by the need for decarboxylation or derivatization of the acid cannabinoids before analysis. Moreover, both decarboxylation and derivatization techniques are subject to efficiency issues.

LC is another chromatographic technique commonly used for decarboxylation studies because it is capable of detecting both neutral and acidic cannabinoids. No decarboxylation or derivatization is necessary using this technique. Veress et al. 10 studied the generation of Δ 9 -THC by heating dried extracts of cannabis over a range of temperature and time, and the products were analyzed by high-performance liquid chromatography/diode-array (HPLC/DAD). Maximum formation of Δ 9 -THC was observed in ∼5–10 min at 145°C followed by a significant loss at longer times possibly due to evaporation of Δ 9 -THC. Dussy et al. 6 also heated pure THCA-A in an oven for a fixed time (15 min) at 120°C, 140°C, 160°C, and 180°C. The reaction products were also analyzed by HPLC/DAD. Conversion of THCA-A was complete at 160°C; however, formation of an oxidation product, CBN, was observed at 160°C and 180°C. Thus, the conversion of the acid to Δ 9 -THC was never perfectly complete without loss or degradation of starting material. In this study, the molar sum of Δ 9 -THC and THCA-A measured by HPLC/DAD was always higher than the total Δ 9 -THC measured by GC, indicating an incomplete decarboxylation reaction. More recently, Perrotin-Brunel et al. 11 studied the kinetics and molecular modeling of the decarboxylation of THCA-A using HPLC. The proposed pseudo-first-order, acid catalyzed keto–enol mechanism for the decarboxylation process was found to be >95% efficient. The major problem with the HPLC/DAD analysis of acidic or neutral cannabinoids is the low molar absorptivity of these components, which results in relatively high limits of detection and restricts DAD detection to low wavelengths where there is often strong background absorbance from the eluant components, especially during gradient elution experiments. This problem can be overcome by using mass spectrometric detection.

Supercritical fluid chromatography (SFC) is a mild separation technique by which decarboxylation of the acid cannabinoids can be avoided. 12 It is fast, cost-effective, and able to provide the resolution necessary to separate neutral and acidic cannabinoids simultaneously. 13 Thus, ultra-high performance supercritical fluid chromatography (UHPSFC) with photodiode array (PDA) and mass spectrometry (MS) detections was used the first time to our knowledge to conduct a decarboxylation study of phytocannabinoids in a solvent extract of cannabis.

Most of the previously reported decarboxylation results emphasized only the conversion of THCA-A to Δ 9 -THC. In the current studies, decarboxylation studies of three acidic cannabinoids, namely, THCA-A, CBDA, and CBGA, were carried out over a range of temperature and time to determine the most appropriate conditions for complete decarboxylation. Beside the neutral and acidic cannabinoids from decarboxylation reaction, the possible oxidation product (CBN), the isomerization product Δ 8 -tetrahydrocannabinol (Δ 8 -THC), and tetrahydrocannabivarin (THCV) were also quantified simultaneously. In addition, the kinetic analysis, including the determination of decarboxylation reaction rate constants and reaction energies, was conducted based on the decrease in acidic cannabinoid concentrations over a range of time.

Materials and Methods

Materials and reagents

Optima-grade isopropanol and acetonitrile were purchased from Fisher Scientific. Deionized water was generated by the Millipore Milli-Q water purification system. Regular-grade carbon dioxide was obtained from New Air.

Nine cannabinoid reference standards, namely, CBD, Δ 8 -THC, THCV, Δ 9 -THC, CBN, CBG, THCA-A, CBDA, and CBGA, were isolated in-house at The National Center for Natural Products Research, University of Mississippi, from cannabis plant materials (structures are shown in Fig. 1 ). The identity and purity of the isolated standards were established by infrared spectroscopy, nuclear magnetic resonance, and liquid chromatography/quadrupole time-of-flight.

Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array-Mass Spectrometry Mei Wang 1 National Center for