pH of unflavored nic liquid?

[Kurt]

Has anyone measured the pH of Box Elder or MFS 100 mg unflavored? Actually it could be any nic level as long as they are the same between the two. I am intrigued by the differences between them, and I suspect there is a pH effect. I don't want to state outright what these differences are...and I emphasize that both are top quality...but there is something nagging me about them. If no one has done this measurement, or doesn't have the equipment/pH paper, I will try to get some appropriate paper next week, but I know there are people here that plotted titration curves. Exo? DVap?

Thanks in advance.
Kurt

 

[rbuck9]

will be interested to see the results

 

[Old Chemist]

That might be an interesting experiment, but we have to think about the method of measurement. Immersing the pH paper directly into the solution wouldn't be the best way, I guess. We have to remember this is not a solution in water, so probably it would be better to dilute a small sample with water before the actual measurement.

 

[Kurt]

I agree OC. pH, pKb and pKa are aqueous properties, but the auto-ionization constant of VG or PG are probably almost the same as water, and I am only expecting qualitative results. So as long as both are in the same vehicle, we should be able to at least see a qualitative effect.

I am expecting one of these is going to be low pH and one high pH, and this is going to explain the different observed "qualities" of each.

OC, do you see where I am going with this?

 

[mrjaguar]

wouldn't pH be dependent on which base solution it was mixed with, PG or VG?

 

[Kurt]

wouldn't pH be dependent on which base solution it was mixed with, PG or VG?

Absolute pH would, but if the two liquids use the same vehicle, both PG, both VG, or both same blend, then the relative pH's would still be instructive. See PG and VG will both have pKa's very close to that of water, so there might be small differences due to one being in a different base than the other, but I am really looking only for pH values either much above 7 or close to/below 7.

I don't like to put a cart (or carto!) before the horse, but I suspect that Box Elder is relatively low in smell and peppery effect because it is pH adjusted to low, with something like citric acid, and the nic is significantly in its salt form, which would be much less aromatic than the free-base nic. I think MFS is high pH because it smells much more of the free-base. It also has a more peppery nose tingle, as the free base would.

This is absolutely not a judgment call on either. I genuinely think both of these unflavored are top quality, and both deliver the nic well and become essentially without flavor in a normal mg DIY. I am struck by the clear potency of Box Elder 100 mg in my DIYs, as I definitely feel the nic in many of the usual ways, but there is a distinct lack of smell of the 100 mg, and lack of nose/throat burn with even a 36 mg DIY vaped straight, and a 36 mg DIY made with MFS will have quite a nice nose tickle...even to the point of sneezing.

As I said, though, this idea that it is related to pH, and thus salt/free-base content, is somewhat conjecture at this point. And the measurement may actually come out opposite than what I am thinking...which would also be useful info. Thing about the pH of a nic solution where very pure nic is used is it will give you a very good idea of the balance of salt and freebase. Simple Henderson-Hasselbalch equation stuff for a weak base (nic) in aqueous solution:

Henderson

The salt may also be able to penetrate to the lungs better than the free-base, which is being used in a nicotine pyruvate salt aerosol device, I think being developed by Ariva. This may or may not be relevant once the salt is in VG or PG, as it is primarily still a VG or PG condensate (vapor). None the less it is information I want, so I can figure out why Box Elder vapes like low nic, but hits the brain like high nic. I am having to cut back on the mg with DIYs made with Box Elder. Was pretty much constantly 15 mg with MFS, but even 12 mg is often too strong now. Could be placebo effect, but my gut says it is not, it is a real difference, and thus should be explainable by simple chemistry descriptions.

 

[mrjaguar]

Ahh, ok, that makes a bit more sense, I FAR prefer my nic to be the non peppery/low-no smell variety. I know of a few places that use that type of nic, nicvape, extremevaping (levi), and boxelder and of course, that's where I buy from.

 

[r77r7r]

....................

 

[Kurt]

Ahh, ok, that makes a bit more sense, I FAR prefer my nic to be the non peppery/low-no smell variety. I know of a few places that use that type of nic, nicvape, extremevaping (levi), and boxelder and of course, that's where I buy from.

So you do not get any peppery from Box Elder either. Ok, so it is not just my imagination. And you have also noticed low smell goes along with less peppery. This is all good info. Maybe others will give their observations too. With MFS I got used to using the "pepper level" as a verification of the calculated nic level of a DIY. I knew what 18 mg should feel like, in the nose especially. And I kinda liked it too. But I am also thinking that the salt will be less volatile, and thus condense onto mucosa and throat more, and be exhaled less. Something is making this juice act far more potent than what I am used to for a given nic level. Used to be that my just-before-bed vape was 12 mg, very low for me. That is way strong now with BE DIYs, and I am having to cut back to about 4 mg, or else it messes with my sleep.

Wonder if anyone else has noticed that BE DIYs seem to be more potent than the nic level says. Of course, I might have gotten a mistaken higher than 100 mg unflavored, but I would doubt that.

I accidentally made a wrong calculation one night, and instead of a 12 mg juice, I made a 48 mg juice from the BE. I would never intentionally vape 48 mg, but even that juice had very little pepper to it...sure did go to my head though!

 

[DVap]

I can recall a long time ago neutralizing nicotine to 100% singly protonated with acetic acic and vaping the result. It vaped fine.

 

[Old Chemist]

Hmmm... nicotine acetate? Not so sure that it's a very good idea.

@Kurt: I agree with you. The question of nicotine base vs cation is really something worth thinking of. As for the measurements - I'd definitely dilute the liquid with distilled water (at least 1:1) - then we would get better results, I guess. Both PG and VG would have a levelling effect. BTW - do you know what is the pK_b or pK_a value for nic solution in water, PG and VG?

 

[Kurt]

If you are vaping Vermont Vapor's juices, you are vaping significant amounts of nicotinium citrate. Adam adds citric acid to lower the pH when he makes his primary base, in order to reduce the stink. VV 35 mg unflavored was my primary DIY liquid for months, and I still have a bunch in the freezer. Nicotine in tobacco is primarily salt form. There is a company now developing a nicotinium pyruvate aerosol inhaler, since salt particles penetrate to the lungs better than PG vapor of a liquid boiling. Acetate should not be any more of a problem then vinegar.

Nic has two pKb's (two nitrogens), one is about 6 (amine) the other about 11 (pyridine). The pKb=6 is the important one for most solutions.

Nic's MW is 162 g/mol. 100 mg/mL comes out to 0.6 M. Thus, and perhaps you can check my math, if the nicotine is only in free-base form, the pH should be for this solution about 10.9. If the nicotine is completely converted to the protonated form, the pH will be about 4.1...this pH, however, assumes the counter ion is a spectator, like Cl-. If it is citrate or acetate, then this is an amphoteric salt, and the solution will be buffered to somewhere around pH 7, depending on the anion. Its less likely that the pH will be lowered with a strong acid like HCl than citric acid or some other weak bio-related acid. For an amphoteric salt, NicH+ A-, the pH will be 0.5(pKa(NicH+) + pKa(HA)).

Unfortunately if it is citric acid being used, it has three pKa's, at about 3, 5, and 6. So to calculate this accurately is very complicated. Lets ballpark it to 5. pKa of NicH+ is about 8. So pH of the solution of the salt will be about 0.5(8 + 5), or 6.5.

So qualitatively, we are looking at a pH range of about 11 to around 6, for the range of all free-base to all salt. I see now that simple Henderson-Hasselbalch, depending on the counter ion of the salt, will be misleading for determining salt to free-base, but I think we will still get a good idea.

 

[Kurt]

I can recall a long time ago neutralizing nicotine to 100% singly protonated with acetic acic and vaping the result. It vaped fine.

DVap, do you recall a lessening of nasal burn, taste and smell? And any difference in perceived potency?

 

[Old Chemist]

If you are vaping Vermont Vapor's juices, you are vaping significant amounts of nicotinium citrate. Adam adds citric acid to lower the pH when he makes his primary base, in order to reduce the stink.

This sounds reasonable. Salt should be almost odorless. Additionally it doesn't evaporate quickly.

Nicotine in tobacco is primarily salt form.

Are you sure? They add ammonia, so...

Nic has two pKb's (two nitrogens), one is about 6 (amine) the other about 11 (pyridine). The pKb=6 is the important one for most solutions.

Right - only the pyrimidine N plays important role here.

Nic's MW is 162 g/mol. 100 mg/mL comes out to 0.6 M. Thus, and perhaps you can check my math, if the nicotine is only in free-base form, the pH should be for this solution about 10.9.

Assuming water solution, right?

If it is citrate or acetate, then this is an amphoteric salt, and the solution will be buffered to somewhere around pH 7, depending on the anion. Its less likely that the pH will be lowered with a strong acid like HCl than citric acid or some other weak bio-related acid.

Absolutely right.

So qualitatively, we are looking at a pH range of about 11 to around 6, for the range of all free-base to all salt. I see now that simple Henderson-Hasselbalch, depending on the counter ion of the salt, will be misleading for determining salt to free-base, but I think we will still get a good idea.

Right. So now it would be interesting getting some experimental data of pH, up to one decimal place.

 

[Kurt]

Yes, they do add ammonia, so more free-base form. I guess I was simply talking about the natural form of nicotine in tobacco, not the enhancement that BT does to the tobacco.

And yes, pKa and pKb are rigorously aqueous properties, so I am assuming water solution. But the pKa of VG or PG is probably very close to that of water, since ethanol is, so I am thinking that the pKa and pKb values in VG or PG should be pretty close to the same as in water...I guess it comes down to the assumption that the auto-ionization constants of PG and VG are close to 1E-14.

But this gets back to my original thought, which is there is probably too much uncertainty here to quantitatively determine free-base or salt content, but between MFS (predicted all free-base) and Box Elder (predicted salt) there should be enough difference in pH to make qualitative assessment.

I threw this out because about a year ago or so there was considerable effort to plot titration curves of the nic in various liquids, and people were actually setting up burets and pH meters and plotting these curves to determine nic content. So those are the people I was hoping would come out of the woodwork as they would have the meters or pH papers and maybe a sample of these unflavored liquids. Its interesting that there was evidently no measurement of initial pH, just the stacked pHs you do to make sure you are starting at low pH and ending up at high pH. Titration mostly for verifying nic content, but no discussion that I recall about initial nic form, which I think is potentially as important.

And I expect this might actually help vendors like Chris at MFS, who seems to be periodically having to placate a customer who thinks his unflavored has too much smell, and thus is "bad", by replacing it. I think MFS is simply free-base, which has its pros and cons, and BE is more neutralized salt, which also has its pros and cons.

And yes, the salt would certainly have a higher BP in pure form than the free-base. But I do not know if this applies to a VG or PG solution, which is boiling off at a higher temp and in bigger molecular clumps, and thus grabbing salt particles in the process. I have never had salt buildup from my VV or BE DIYs in, say, an atty or carto. At least not that I can tell. Similar to the classic classroom steam distillation of high-boiling eugenol.

 

[DVap]

DVap, do you recall a lessening of nasal burn, taste and smell? And any difference in perceived potency?

I recall very little other than the impression that the difference in experience was minimal.

 

[tceight]

Hmmm... nicotine acetate? Not so sure that it's a very good idea.

care to share your reasoning why this would not be a good idea?
I've vaped a lot of nicotine acetate, as well as other salts... citrate, malate, tartrate, chloride, etc.. and have experienced no negative acute effects. If you are aware of any potential chronic effects, please enlighten me!

 

[Old Chemist]

No acute effects. How did you check this? Any lab results?

 

[tceight]

I meant no immediate obvious general negative reactions, as in the medical definition of acute symptoms. No subacute either that I noticed.
as for chemically acute toxicity, I wouldn't know, and would have had no reason to suspect such with acetate. Hence, I asked.

I'm still unenlightened, and can't find anything in the medical journals.
is this opinion based on something specific you know, or your general impression/opinion based on experience?

 

[Kurt]

Well, huh. I used pH paper, sometimes called alk-acid paper, which has color from deep red for pH 1 to deep blue for pH 12. Just a dab from each of these 100 mg VG liquids on a strip of the paper, and both come out to blue with a hint of green, which is in the pH 9 - 10 range. So it seems both are at least mostly free-base. There is no water in either, just VG, so it could skew things a bit, but 100 mg of pure free-base dissolved into 1 mL of aqueous solution should have a pH of about 10.8. So it seems they are BOTH all or almost all free-base.

So I retract my previous predictions that the BE will be lower pH. Something else is reducing and changing the smell and taste in it. Perhaps the MFS is lower grade nic, and it is the impurities that doing this. But generally lower grade nic will give a strong yellow, or deeper, color. And this is certainly NOT the case with MFS. If you didn't know you would think it is just VG to look at it. Same with BE.

So why such a difference? Not just with the taste and smell, but also the sensation of the vapor in the nose. I do want to restate, however, that it is smell of the 100 mg. Both of these in a DIY essentially vanish, other than the nose burn, which is clearly more with MFS than BE at the same nic level, same % water to this, same flavor and %. I consider both to be excellent nic, and if I needed more I would not hesitate to buy either. But MFS is a "pepper nic" and BE is not.

I am not at all the first to note the differences between these two. And sometimes I'm a pepper. I actually missed it when I was just vaping my BE DIYs...I wanted that nose hit, since I primarily inhale only shallowly and slowly let the vapor come out of the nose, like with a pipe. So I made the same DIY with the MFS 100 mg, and boom there it is.

What in the world gives here? I am most puzzled by this.