Which Chromatography method is the best: Column or Gas?

We have been asked this question many times and I have been avoiding answer it until now.

Let’s start by saying that Chromatography uses Polarity differences as a method of separation for different components.

We are going to make a very brief explanation of the 4 more common types of Chromatography. And we will move from that to make a decision.

First of all, the word Chromatography comes from the union of two words: Chroma=Color and Graph=Graphic; because when Mikhail Tsvet was trying to separate chlorophylls and carotenoids in1906, he saw that by using a thin layer of papers with adsorbents like calcium carbonate and a mix of eluants such as petro ether/ethanol, the “Colors” of the plant pigments were seeming very clear to the point that a “Graph” could be presented to explain the results.

Chromatogram with many different Cannaboniods identidied

From those earlier graphs we have come a long way to the point that now we have very detailed Chromatograms but the principle is still the same. We are using the polarity differences on every component to separate them using either an adsorbent (bead/silica/paper/material/liquid) that we call now Stationary Phase with a Mobile Phase than can be Liquid/Solvent/Eluant/Carrier/Gas.

When one is trying to do some analytical tests or studies, one might use Paper or TLC but if one is planning to bring those results and make them on an industrial scale size, they need to think about only two options: either Column or Gas Chromatography.

Column Chromatography

The idea here is to use a Polar or Non-Polar silica as stationary phase and choose the right Eluants to prepare the perfect liquid mixture (most of the time on different gradients at different points of the process) to use them as Mobile Phase to obtain the best Elution for your sample.

It is very important to mention that before one prepares to do some Industrial scale designs, one must prepare and develop their own method on an analytical HPLC system before they jump into any kind of conclusions.

As we always say: The key element is neither the size of the columns nor the maximum injection pump rate nor the efficiency of their mass spectrometer nor the ability of your UV detector;rather, the person developing the method.

HPLC Analytical Setup

For cannabinoid separation, the majority of Labs are using silica C18 but we have seen some using C8 as well; most of them are using Ethanol, Ethyl Acetate and purified water mixture as mobile phase. But again, each method should be tested and developed by someone with proper knowledge.

A factor that almost no one is considering here is the amount of solvent recovery systems that needs to be built around chromatography columns, especially when you are talking about processing thousands of liters per month, week, or sometimes days.

We have seen methods developed where the ratio goes as low as 16:1 but others as high as 63:1.So imagine using the bigger ratio and trying to process 200 liters per day. One would be required to calculate, design and build a Solvent Recovery System that can recover 12,600 liters per day. Think about that. Even working 10 hours a day, one would be required to recover more than 1,000 liters per hour. Let that sink in.

High Pressure Liquid Chromatography Setup

Gas/Liquid Chromatography

This separation technique uses a liquid as a Stationary phase and the Mobile phase and sample are used in a Gas form, the carrier gas is most of the time Helium, but Nitrogen and Hydrogen are used; but not too often. The concept is that Gas chromatography uses a high boiling point, because the higher the boiling point the faster the molecule will move through the column in its gas form.

One very important detail regarding the proper gas to use is that one must utilize an inert gas like Helium; other inert gasses that are sometimes used, like we mentioned before, nitrogen and hydrogen.

Some advantages of using gas chromatography (GC) are high resolution, high accuracy, high speed and high sensitivity. High resolution with gasoline, for instance, has been dissolved from 300 peaks from petroleum. High sensitivity has allowed us to detect some pesticides like Methyl Parathion, Malathion and Ethion on picograms levels in less than 2.5 minutes.

The limitations are also as important as the advantages, because the samples and the mobile phases need to be on a volatile state, and sometimes dirty samples can destroy the column. Like the column chromatography,one needs to use mass spectrometers to collect the molecules for proper separation.

One very big limitation is that one cannot use it for peptides nor proteins, because one cannot analyze biological samples. Those are better done using columns with liquid mobile phases.

Which Chromatography is the best one then?

Like we say with extraction systems, there is no perfect solution, one needs to consider what is the material that they are extracting, what is the volume they are processing, what products are they creating at the end? And many other factors that will allow one to decide which extraction system is better for them.

Sometimes Ethanol is the best option; other times C02 is the best route and in our humble opinion, Butane/Propane could be the best system to do extraction for Hemp and Cannabis but the risk of handling those volatile products make it almost impossible for large scale extraction solutions.

In the same way when many are trying to select either one or the other Chromatography columns the answer is not that simple. Both options have their advantages and limitations.

But if anyone forced our hand to make a decision, we will use Column Chromatography with liquid mobile phase all day long over Gas Chromatography if you are using it for Cannabinoids, of course.

One last thing but the most important one if you ask us is to outline that Chromatography has been chosen by many labs to “remediate” distillate and even Full or Broad CBD spectrum Crude Oils; but honestly, Chromatography should be considered as the “Perfect Solution for Consistent Formulation”.

What do we mean by that?

Chromatography Columns will give one the ability to identify, quantify, detect and collect as much as 14 molecules (cannabinoids) at once, and do not get us wrong here, we said collect 14 different cannabinoids on every single run we do based on the Method that has been developed. However, the mass spectrometer and the UV-detector can identify as many cannabinoids as you have in your sample.

Chromatography columns provide the perfect solution to consistent formulation by having the ability to get every single cannabinoid isolated. Meaning “pure” CBD, CBG, CBN, THC, CBDA, etc and noticed that we “quoted” pure because you can reach 99.99% purity but the more pure your isolated cannabinoid the more time one will need, the less volume one will process and more expensive it will be.

But if we want to have consistent formulations in our tinctures, topical, vapes and the rest, we need Chromatography to provide us the single Isolated cannabinoids or Terpenoids that our formula demands. 

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Let us help you if you need chromatography solutions for your Lab.