Comparing Organic Solvents: Is Denatured Ethanol Safe for Extraction?
The CBD industry is reliant on the extraction of this particular cannabinoid so that it can be formulated into various products like tinctures, vaporizer pens, balms and lotions, and more. While there are a number of ways to accomplish this, each solvent has potential benefits and downsides when used in any extraction setting.
For this reason, it is important to take a careful look at these solvents to determine which is the best for a given extraction setting. By comparing these organic solvents, producers can make a thoughtful choice in their extraction business that will allow for a safe, profitable extraction operation.
Types of Organic Solvents Used For Extraction of Hemp
A solvent removal process is only necessary if it is present in the sample after extraction.
Most common organic solvents include ethanol, butane, propane, and CO2. Relevant organic solvent properties are included in the following table:
Table 1. Organic Solvent Properties for popular extraction solvents used to extract cannabinoids and bulk oils from hemp.
|“>State at room temp and atmospheric pressure||“>Liquid||“>Liquid||“>Gas, liquid at extraction pressures||“>Gas, liquid at extraction pressures||“>Gas, liquid at extraction pressures|
|“>Boiling Point||“>78 oC||“>209oC||“>-78.46 oC||“>-1 oC||“>-42 oC|
|“>Vapor Pressure (mmHg, 21oC)||“>44||“>40||” data-sheets-numberformat=””>44,151||” data-sheets-numberformat=””>1,830||” data-sheets-numberformat=””>6,398|
|“>Flammability||“>Category 2||“>Category 0||“>Category 1||“>Category 1|
|“>Log P (octanol-water)||“>-0.18||“>4.27||2.0 at 1500 psi”>”>0.9 at 450 psi
> 2.0 at 1500 psi
As can be seen from the chart, each organic solvent has its unique characteristics and therefore has different advantages and disadvantages as an extraction solvent. One of the key differences is the state that the solvent is in at room temperature and pressure.
Depending on the volume of ethanol stored and deployed during an extraction, specially certified equipment and facilities may be needed for solvent recovery operations. Ethanol has a low vapor pressure and therefore is not as prone to vaporize compared to CO2, butane or propane. In the case of ethanol extraction, the hemp extract is a highly diluted, volumous mixture of oil and ethanol. That ethanol mixture is considered a class IIB solvent that is a Category 2 flammability hazard.
A typical rule of thumb is that the maximum amount of ethanol that can be left in the extract is 5000 ppm if it is to be used as an ingredient in a formulation. In practice, organic solvent recovery is deployed to remove the bulk of the solvent so that it can be further processed by a wiped film evaporator.
This is in stark contrast to CO2 which does not require a special post CO2 removal process due to CO2’s high vapor pressure (45,600 mm Hg) at room temperature. The CO2 may be safely vented or recompressed for reuse. Due to the fact that CO2 is not flammable, no precautions other than a Co2 meter and exhaust are required to be deployed for venting on a CO2 Extractor. If the extraction facility is located near a greenhouse, the CO2 may be incorporated back into biomass by venting into the greenhouse.
Similar to CO2, Butane and propane also has a high vapor pressure (1830 mmHg) compared to ethanol but due to sluggish transport through the viscous extracts, butane extracted resins often have high butane residuals. These extracts therefore often undergo post extraction vacuum distillation by placing the extract in a vacuum oven.
What is Denatured Ethanol, and Can I use it for Extraction?
Denatured ethanol is a mixture of denaturants (heptane) and pure ethanol. Chemical companies add the denaturant to pure ethanol so that it will not be consumed as a food without paying excise taxes. Denatured Ethanol extractors use it to reduce the costs associated with ethanol losses.
A wide variety of denatured ethanol recipes are published by the TTB that is administered by the National Bureau of Alcohol Tobacco and Firearms. One of the most common denaturants used in ethanol extraction is heptane. However, there are other substances that may be used including acetone, isopropyl alcohol, methanol and other longer chain alcohols.
One advantage that dilution with heptane has over other recipes is that the ethanol and heptane can be separated fairly easily due to the large differences in boiling points. There are still residuals to consider here but clearly the operator can avoid a major cost associated with food grade ethanol by distilling denatured ethanol and the distilled ethanol in the food grade process. The limiting factor to consider in this kind of distillation operation is the solvent reuse guidelines given by the FDA as outlined below.
The other key consideration for the use of denatured ethanol in an extraction process is chemical contaminants known as residuals. Residuals will always be present even with a pre-distillation process as described above. However, the residuals may be so dilute as to be considered “trace” components. Chemical manufacturers insist that their denatured ethanol products are safe and approved for food production but they have no data that establishes its safety.
For example, there is NO data on the safety of heptane over long term human exposure. NIOSH has published many warnings on the exposure of heptane and has warned that occupational hazards are unknown. The FDA has advised that chemical contaminants should be limited as much as possible and generally accepts the guidelines outlined in the USP that limits these class 3 chemicals to a maximum of 5000 ppm. The limits established in the 1990s by the FDA/USP recognized that there was not sufficient clinical data available to limit its presence in drugs. So, they agreed to 5000 ppm.
In support of their decision, they cited a single study published in 1981 on the effects of heptane exposure on ten Sprague Dawley rats. Based on this information for heptane and other similar information for other solvents, the FDA agreed with the global pharmaceutical manufacturer’s associations to solvent limits for three classes of solvents. That is why there are many disclaimers about the unknown effects of these solvents. The bottom line is that the effects of residuals may be unknown and the buyer of the products that have residuals should be aware that residuals may be present even if they are not reported as actionable by USP .
Denatured Ethanol For Extraction
Is it safe to use denatured ethanol for extraction? Denatured ethanol is a form of ethanol that is diluted with other solvents such as acetone or IPA. Denatured ethanol can be used in extraction processes and is often utilized by any extractors looking to avoid the higher costs associated with using pure ethanol. As long as the denaturants used to dilute the ethanol are food grade, and safe for extraction, then using denatured ethanol for extraction is perfectly fine.
One very important detail to consider when looking for the right extraction solvents for your process, is contaminants. You want to be sure you are using a food grade solvent that has a high purity level. This means that the solvent has very low contaminant levels, ensuring it is safe for producing oils used for cooking or personal care. This includes oils like olive oil, CBD oil, seed oils, and other common oil products. If you are looking for a solvent supplier who can help you find denatured ethanol or other high purity extraction solvents, Ecolink can help!
Benefits of Ecolink’s Denatured Ethanol For Extraction
- High Purity – Ecolink proudly supplies high quality, high purity chemicals. This provides you with peace of mind, knowing you will produce a high quality, safe to use product. The use of these high quality chemicals also helps to protect your facility, as employees will be handling stable chemicals and solvents.
- Bulk Availability – Ecolink offers bulk sizing options including 5 gallon buckets and 55 gallon drums. This provides the convenience of always having enough supply on hand, while also offering the advantage of bulk pricing.
- Expert Advice – If you need help finding the right solvents for your needs or want to learn more about proper use of denatured ethanol for extraction, one of Ecolink’s dedicated chemists will be happy to help. Ecolink will work with you to ensure you find the right chemicals to get the job done and understand proper safety protocol and storage to keep your facility safe.
Want To Learn More About Extraction Solvents?
For more information, contact Ecolink here to find the right chemicals for an affordable price! Our knowledgeable team of chemical experts is ready to help. Call today to get started!