Hey all, new here first post - let me know if I am in the wrong place please. I have tried searching the forum, and web (which initially led me here actually).
I’m not scientifically minded at all. I’m trying to figure out the specific gravity of a solution of CBD isolate dissolved in PG.
Where I am at right now:
I have a solution of 30ml PG, with 7.5g of CBD isolate dissolved in it
Questions
Would I be correct in saying this is 250mg/ml (7500mg in 30ml = 250mg/ml) of CBD isolate solution - or do I need to account for the volume/mass of CBD isolate added when considering my 250mg/ml figure?
I have a (probably inaccurate) re-usable pipette that I used to measure 1ml of this solution 5 times to get the average weight of 0.964g per 1ml of solution. From what I’ve read, this is the specific gravity I could use to lets say calculate any Xmg/ml final solution by weight in grams?
For example, a 800mg solution would require 3.08g of my 250mg/ml base, would this be correct?
The other thing I am curious about is: I have found sources that the specific gravity of PG is greater than 1 at 1.038.
My solution’s specific gravity is below 1 at 0.964 - is this because dissolving the CBD would reduce the density of the liquid?
Again, sorry if this is in the wrong place - I’m just learning, appreciate any help.
The what and the who now? Didn’t know about these things so thanks for that.
After doing a bit of reading, I don’t think the Hydrometer is a good way to go as it will waste far too much end product - or at least increase the chances of contamination too much that I’m comfortable with.
The refractometer looks promising, but I can’t seem to find one that measures specific gravities (SG) below 1. Also, the ones related to PG are all to do with anti-freeze and the SG of battery acid.
I’ll keep looking, will see if I can find a refractometer that reads SG below 1, or in the 0.8 - 1.2 range if that’s even possible.
There’s a more straightforward way to do this. Take a 25-50 mL class A volumetric flask and tare in on a 2-4 place balance. Add your fluid to the line in the usual way. Take the weight you get and divide by the volume of the flask. You have the density.
Question 1 : if you mixed 30 ml of solvent and 7.5g of cbd, your total volume/mass has changed at the end. You got to take the total volume/mass into account to calculate concentration.
Qiestion 2: I did not checked if your calculation is correct. In any case the method employed to determine the density of your product is not appropriate. Such product is not viscous enough to be pipeted without loses (on pipettes walls).
The above suggested method, using a large enough volumetric cylinder and a precision scale is much more appropriate. Pay attention that The density depends ob temperature.
Question 3: you should expect a density above one with such mix.
On Q1: That’s what I was thinking too - I’m sure its probably negligible on the scale I’m doing it in - but I’d still like to know how to get it as accurate as possible. I think instead of starting with a known volume, it seems the easiest way is to start with the CBD isolate, and add PG until the CBD is dissolved, and the solution is at 30ml (in this example) - which would then give me accurately 250mg/ml.
I have started looking into the molecular weight of CBD isolate (314.46 g/mol if anyone is wondering - so 1g of CBD is 0.003180054697 Moles); as well as calculating concentrations of solutions but this is way out of my league. I think the above would be the most straightforward thing going forward on new batches, or would this still be incorrect/inaccurate?
On Q2: That is also agreeable from what I’ve observed. The solution is very sticky and takes quite a while to pool for me to spit out of the pipette.
I’ve ordered a more accurate scale and volumetric cylinders to try again. Ireland has very mild climates so it’s never too hot here; but thank you for that too.
On Q3: I thought this too, I immediately thought it was because of as you’ve mentioned how the CBD in PG solution is not viscous enough and I thought there was far too much getting stuck to the sides. I tried spending a lot of time waiting and making sure I got as much as I could out of the pipette on each measurement.
I also thought about how light/fluffy the CBD isolate is and thought maybe it was possible to lower the density of the liquid but I was just guessing on this, not having any knowledge on the subject.
Thank you for all your inputs on this, much appreciated!
and the SG of battery acid.