What is short-path distillation? How does it work?
Short-path distillation is a simple technique that involves the
distillate traveling a short distance. This technique is used in many
types of distillation and has been around for many years in several
fields. This distillation is completed under pressure which decreases
the boiling point of the liquid.
Due to the lower boiling point, it is a good procedure to use for
compounds that are unstable at high temperatures or to purify small
amounts of a compound. The classic setup involves minimal travel for the
vapors, hence the term short-path.
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What applications use short-path distillation?
While general distillation systems in the laboratory can be elaborate
and extensive, the short-path strategy utilizes less glassware which
reduces potential loss of materials adhering to the inner surfaces of
the apparatus. This technique is employed where product loss during
processing can be expensive.
What role does short-path distillation play in cannabis applications?
The process when using THC is often called fractional short path
distillation. In the distillation process, you can extract the hundreds
of cannabis compounds out individually because each compound has a
different boiling point. After the extraction is complete you can add
together the known compounds you want to make the best product for the
customer.
Due to the expensive nature of the materials involved with cannabis,
the short-path distillation technique contributes to the profitability
of the processing operation.
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Image Credit: shutterstock.com/RoxanaGonzalez
Why is it a crucial step?
The crucial aspect of distillation purification is temperature. Other
physical chemistry variables contribute to the effectiveness and
efficiency, but temperature is critical to achieving a high yield of
desired products. Vacuum is often used to enhance the process by
allowing distillation at lower temperatures thereby reducing the
potential of altering the chemical makeup of the distillates.
The short- path distillation is a crucial step to get the end
product, CBD oil without terpenoids, flavonoids, and contaminates
(by-products like residual solvents and pesticides can be removed).
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Image Credit: shutterstock.com/ElRoi
What is the difference between extraction and distillation?
Distillation and extraction are extremely similar as they are both
separating compounds. The difference is: Distillation is separating
compounds based on boiling points. Extraction is separating compounds
based on solubility in the extraction solvent.
For the cannabis industry, extraction involves the collection of oils
from the plant material. Whereas distillation describes the process of
purifying the extracted oil into desired constituents which can be
incorporated into marketable goods.
How does short-path distillation separate organic and inorganic compounds? Why is this important?
Short-path distillation separates components from the extracted oil
by capitalizing on the differing chemical characteristics of the
constituent compounds. The solubility and vapor pressure of compounds in
a mixture (among other characteristics) affect the evaporation step
during distillation. By selectively targeting these physical properties
of the materials involved, the experimental conditions for collecting
predictable and reproducible constituents can be identified.
This is done primarily through measuring the vapor temperature and/or noticing a color change. The distillation is completely reliant on temperature.
Glas-Col. “Using Short-Path Distillation to Extract CBD Oil From Cannabis”. AZoM. 19 June 2019. <https://www.azom.com/article.aspx?ArticleID=17026>.