Any interest in determining nicotine--by DVAP

[HighTech]

Excellent post DVap, enjoyed the read. Thanks for posting.

[DVap]

Getting back to the question that came up about storage of bulk e-liquid for maximum shelf-life. I know there has been a lot of speculation in the forum on this question, and very often folks just go with the supplier's recommendation.

If you want to store e-liquid long-term, the simpler the better. I really have no recommendation for storing flavored liquids, each liquid is unique, and each ingredient has it's own potential for going bad. I suspect, with some flavored liquids that have "gone bad", this has nothing to do with the nicotine, and everything to do with one or more of the flavorings. With flavored liquids, you're on your own.

A mixture of essentially propylene glycol and nicotine has a lot less that might go wrong with it than a mixture of propylene glycol, nicotine, and a bunch of components added for flavor.

So, here's what I would do for long-term storage. Other opinions may differ.

1. Keep it simple, the closer you can get to just propylene glycol and nicotine, the better. (Though I think most liquids also contain a small percentage of water, perhaps to help with nicotine's miscibility with PG?)

2. Store it dark.

3. Store it cool. (20°C should do, I really don't know if refrigeration will help, kinetics at room temperature 20°C/293°K aren't that much more energetic than at -10°C/263°K).

[DVap]

For those of you still following this, I've run a test I should have done previously which goes a long way toward validating the nicotine determination procedures detailed in posts #26 and #28 in this thread.

I didn't do this previously because I looked at some theoretical data that told me I didn't have to, still it's always a good idea to dot the appropriate vowel and cross the appropriate consonant.

I made a 0.1N NaOH solution and added 30 drops of bromothymol blue to 10 mL of this base solution. I added 40 mL of distilled water. This gave me a very pretty deep blue solution. If my 0.1N acid solution was made correctly, 10 mL of the acid solution would be required to neutralize the base solution. 10 mL of acid gave me a pale yellow/green solution, and the next drop of acid turned it all yellow. So I made the acid correctly at 0.1N, good for me. But this wasn't the purpose of this test (though it's always good to double check).

I place 25 ml of the 0.1N NaOH, 10 mL of PG and 5 mL of VG in a flask and added 30 drops of the bromothymol blue solution. Sound familiar? By doing this, I've approximated the matrix of an e-liquid. Will the presense of the PG and VG affect the volume of 0.1N acid required to turn the solution yellow? It should take 25 mL of acid to turn yellow, and it did take 25 mL of the acid to turn yellow.

So now I'm much more confident that the e-liquid matrix should not affect the result.

[Kewtsquirrel]

Hey DVap, if I send you a sample of the 7.5% bliplabs liquid I bought could you test it for purity for me? While I know this stuff is *far* stronger than anything else I've tried, it'd be nice to know it is indeed exactly 75mg/ml.

[moshinator 2]

Priceless info. Dvap... thankyou.

[DVap]

Nerf, just fire me off a PM... Or better yet, I'll send you a PM.

I can't really say much about purity.. it could have lighter fluid in it for all I'd know. But I can tell you about the nicotine percentage.

[DVap]

I'm getting the germ of an idea for a couple experiments.

Set up an e-smoking machine that draws the vapor through an impinger with a dilute sulfuric acid solution with a force similar to inhalation to trap any nicotine in the vapor as nicotine sulfate. Set it up for 5 second "puffs", topping off the cart after every 10 puffs. Repeat for 100 puffs. Isolate the nicotine from the impinger and determine ug nicotine/puff.

Or, load up a cart with e-liquid that I've already determined for nicotine. Vape it for awhile, topping off as needed. Determine the nicotine in the liquid remaining in the cart to determine if vaping preferentially pulls off the PG and concentrates the nicotine in the cart. (This being a pet theory of mine that could well be right or wrong).

[DVap]

BTW, thanks for the interest, guys. I've enjoyed geeking out here.

Chemistry is one of those disciplines that can throw a bit of light into the black-boxes that surround us in our day to day lives.

[Tom09]

DVap, that’s seriously the most exciting thread in this forum for months. I highly appreciate your work on this subject, certainly enjoyed reading up how your experiments evolved.

I seriously hope that you will follow up on your new ideas. Both questions about nicotine per puff and about possible fractionation will be very interesting. May be you are aware of the FDA report (Westenberger 2009). Westenberger had sat up an e-smoking machine, too, to determine nicotine per puff. I really wonder about the large variations he reported (43.2, 34.9, 26.8 mcg nic/ 100ml puff) - and which just became a point to be blamed on bad manufacturing practice in the FDA press conference. Well, true reason could be anything, including dying batteries, drying carts or even fractionation.

Anyway, nice to see you’re having fun in geeking out

[DVap]

Hey Tom,

I'd never seen that report.

As far as inconsistency in ug/puff (or mcg/puff), I'm more of a mind to blame it on that flawed piece of technology we lovingly call the "atty". Don't even get me started on cartridges.

The FDA, pardon my lack of tact, can kiss my ass. True, I have a dog in this fight. If I did not, I would still find their testing to be spotty, their experimental design to be prejudiced (Burn a Marlboro or two, you prats!), their conclusions to be leading, and their lack of conclusions to be telling.