GC-FID App Note – CBD in Oils, Lotions, and Chewables
by Daniel Iversen, R&D Chemist, Lucidity
With the introduction of CBD in so many products, making sure that the labeled amount is what
the consumer is getting. Many studies have been done on the CBD oil tincture, so I wanted to
focus on something a bit different. My father-in-law uses CBD hand cream to help with his
arthritis and I wanted to know if I could test for the CBD in hand lotion and other products
infused with CBD.
I got some hand cream, lip balm and a sugar scrub. I figured that these three products were
different enough from the typical CBD oil that they would be interesting to analyze. I had to get
to work on extracting the samples. I first tried to use just methanol to extract the samples, to no
success. I had to change tactics.
I then thought that I would need a fully non-polar, so dichloromethane was my solvent of
choice. That didn’t work out either. I was left with a slimy mess of a sample. Hand creams go
on skin and need to be absorbed by the skin so I tried water to dissolve the sample, which
worked better than DCM alone but I still had the emulsion that needed to be broken down.
I reached out to some of my colleagues and was told that methyl tert-butyl ether (MTBE) along
with methanol would put the lotion into solution. I made a 1:1 solution of MTBE:methanol and
added 1.0 g of the lotion. After shaking the solution for several minutes, I then centrifuged the
sample for 5 minutes. The solution was then filtered into a beaker where it was submerged into
a hot water bath for evaporation.
Once the solution was completely evaporated, I was left with residue, that when cooled turned
to a waxy solid. I added 20 mL of methanol and stirred the solution until the waxy solid was
completely in solution. I vialed up 2 mL into a GC vial and headed to the miniGC.
The programming for the miniGC is as follows:
| Lucidity miniGC Conditions | |
| Carrier Gas | Hydrogen |
| Control | Pressure |
| Flow | 1.10 mL/min |
| Split | 10:1 |
| Column | MXT-5, 30m x 0.25mm x 0.25um |
| Injector | 200 C |
| FID | 300 C |
| Oven Profile | Ramp from 200 C to 300 C at 15 C/min Hold at 300 C for 5 min |
Next, I produced a calibration curve of CBD from 20 ppm to 1000 ppm CBD. The resulting curve was linear and had an R2 value of 0.999.
Once the calibration curve had been established it was time to run the sample of lotion. I waited
for the chromatogram to be produced to see if the sample prep had worked on this sample.
When the run was finished I was pleased with the results. The chromatogram was clean and
showed the CBD peak well.
| CBD (ppm) | % Recovery | |
| Lotion results calculated | 15,841 | 105.6% |
| Lotion reference | >15,000 |
Using this I was able to calculate the content of the CBD in the product as 15,841 ppm, I went to
the manufacturer website to get a CoA but the lotion didn’t have a CoA so I had to go with
what was labeled on the bottle which was >15 mg/mL, so I assume roughly 15,000 ppm. This
gives a 105.6% recovery for the lotion / muscle rub cream.
I was now convinced that this method should work for the lip balm and sugar scrub. So I got to
work. Following the same sample prep procedure I was able to obtain the following
chromatograms.
| CBD (ppm) | % Recovery | |
| Lip Balm results calculated | 18,338 | 103.9 |
| Lip Balm reference | 17,647 |
| CBD (ppm) | % Recovery | |
| Sugar Scrub results calculated | 6,769 | 95.9 |
| Sugar Scrub reference | 7,055 |
For the lip balm the label stated that it had 15 mg, I assumed that meant 15 mg/g of product.
The results from the GC gave a 103.9% recovery.
The sugar scrub was the same, no CoA but a labeled amount on the container of 7 mg. This
time the recovery was a bit lower at 95.9%.
After those two samples, I was eager to try something that had a CoA with it to test out my
sample prep and calibration curve. I found some CBD pills that had a CoA content for CBD and
CBG. I figured that I could modify the steps to my sample prep and got started.
The major change was that I didn’t use the MTBE, as I didn’t need to break an emulsion. I
crushed the pills with a mortar and pestle, added the powder to a beaker and added about 50
mL of methanol to do the extraction. I allowed the solution to stir for 10 minutes, I then filtered
the solution into a second beaker and used my hot water bath to evaporate the methanol. Once
everything was evaporated I added back in 20 mL of methanol and swirled the mixture. I then
injected the solution onto the Lucidity miniGC and waited. I was surprised at the results, there
were just two peaks, one I knew as CBD and the other I assumed was CBG.
| CBD (ppm) | % Recovery | |
| Pills results calculated | 17,767 | 103.3 |
| CoA | 17,200 |
Using the calibration curve I was able to calculate a CBD concentration of 17.8% and the CoA
value of CBD was 17.2% for a recovery of 103.5%, not too shabby! Now this second peak
caught my interest. I hadn’t created a CBG calibration curve or even planned to do any
calculations with CBG in this study, but I was curious. I used the amount of the CBD that I
obtained and divided it by the peak area of CBD, then I multiplied by the peak area of the CBG
peak to get 52.1% CBG. The CoA results were listed at 52.7% for a percent recovery of 98.8%.
I know that this isn’t the way to quantify peaks but I just wanted to see if I could even get close
to the CoA value of CBG.
Overall, this study was a success in the quantification of CBD in lotions and other cosmetics
using a GC. The major issue to overcome is the breaking down of the emulsion without
compromising the analyte of interest. The MTBE does a great job of breaking the emulsion to
allow for the extraction of the CBD using methanol.