Types of nicotine base liquid

Discoloration is generally from nic-oxides, formed from the natural oxidation of nicotine with O2. Yellow to brown is almost certainly from those. They are harmless, that we know of, but it requires only trace amounts to strongly color a liquid.

Pink-rose color is something that was discussed in one of the techie forums here quite a while ago. We don't know what it is from, but I am almost certain it is a colored complex (loosely associated compounds with each other) of nic-oxides with VG or some flavor. Not all color from chemicals is from a reaction. Compounds that would be colored by themselves, like oxides, can change their color a little when associated with another compound. It could well be a trace compound left in the original extracted nic, and this seems likely. Only a GC-MS would sort this out, IMHO. But again, it requires only minute quantities of such a complex to produce visible coloration. It could also be a complex formed with a flavor compound, but while I have seen the pink, I've not been able to narrow it down to a particular flavor note, or even a particular flavor from a vendor, like Capellas. I have seen the pink form over time with one or two of my unflavored liquids I make, but not in a long time.

I think it is possible that some flavorings catalyze oxidation. Loranns bavarian cream always gets very dark after a few weeks, but I don't think it is a different reaction taking place, just an enhancement of a reaction that will take place regardless in a juice opened for use.

In all these scenarios, the total nic content should not change a lot, unless we are talking about an opened juice that is many months old.

 

Vermont Vapor adds citric acid to lower the pH and resulting smell of the freebase by partially turning into the citrate salt. I like their liquids and have not had issues with their unflavored in DIYs in terms of attys...although I'm more of a carto man these days.

How it is with inhalation is an interesting question, although I suspect that once its in VG or PG it is a moot point, since you are inhaling droplets, not solid salt particles. That said, pyruvic aicd has been added to nicotine in a new nic inhaling device that may be poised to hit the market. the idea is that the salt particle, and this is something like a aerosolizing system, not a boiling liquid system like PVs, will penetrate to the lungs better than gaseous nic freebase. So more like an ash particle than a vapor cloud droplet, which we know is mostly oarally absorbed in the mouth, nose and throat not the lungs so much. So in that respect, acidifying to form nic salt is being considered, probably as a fine powder in a propellant, like an asthma inhaler.

Since freebase is a neutral amine which is rather volatile, and the salt is a much higher BP, because its an ionic solid, this seems to have a smell reduction effect. At least that's what I was told.

In terms of my titration method, or any titration for nic, it will complicate the results a lot, I think, since these salts I am describing have strong buffering capability, and thus it will, be the least, act as though part is already titrated, thus giving a low result compared to the actual nic content, or at worst will just not titrate well at all, or give a titration curve somewhere between that of nic and that of the citrate or pyruvate, both of which will be titrated with a strong acid like HCl.

 

I ran a series of tests a long while back to try to get to the bottom of the pink-rose color, but ended up throwing up my hands and resigning myself that I couldn't run it to ground. I quite agree that the root cause is likely trace compounds in the source nicotine. I did, however, more closely associate the pink-rose color with nic/PG mixes than nic/VG mixes.

 

The GC/MS testing we've had done so far indicates there's definite esterification associated with (at least in PG mixes and fruity flavours,) nic base discolouration. It doesn't affect assay accuracies, nor the subjective "hit" or flavour. VG solutions are far less prone to this, but PEG-400 will (a little more gradually than PG pinks) turn yellow/orange under similar exposure to light/heat/oxygen.

 

Well, I only vape VG juices, but they can have a little PG from the flavor. I've only had two juices go rose that I recall. One was an unflavored 24 mg VG, and the other was a vanilla I made, don't recall the strength. So maybe if I used PG more, I would see it more.

I have often thought that oxidation is slowed in VG just from viscosity and lower of thermal diffusion of the nic. If it doesn't find an O2 molecule it won't react. Color is a sensitive thing. If an oxide is yellow by itself, it can be another color if it even loosely binds with something else, like a pi-stacking thing. But this is speculation. It seemed it was something that was appearing over time, rather than rose all of a sudden upon making the DIY.

@Nick: interesting about the esterification. Fruit flavors are mostly esters themselves. I had thought for a long time that if there is water present, there can be a base-catalyzed hydrolysis to form an acid and an alcohol. Long chain alcohols will often have a wet-dog flunk to them, while acids that form would have a sour/vinegar/puke taste. This happened with a bunch of JC a couple years ago. Unopened bottles in the fridge went yuck after about six months.

What esterification do you think happened? Reaction with PG or VG? Flavors for me are still the great unknown in this field.

Roly, this is I think OT to your OP, but just tossing it out.

 

As it is really really late here, I just want to place a marker, so to speak, that I'm not in favor of acidifying e-liquids; the dangers, though mild, are hidden (not obvious in the vaping experience). Hope to get back to this topic when more lucent.

+++

Better add something. It goes back to the 'elephant in the room thread' - flavoring and additives such as sweeteners have been added in abandon yet are actually the prime focus of concern re vaping safety, imo.

It has received almost zero interest, but it is clear that 'vaping' is not really pure vaporisation but to some degree also a mistification of the liquid such that constituents w/o a suitable boiling point / vaporisable potential can still be emitted (to some extent) into the 'vapor' stream. But this is likey only partial and the rest of these constituents will heat decompose within the PV device near on the heater element.

So until there is good evidence that I;m wrong on this, I'm opposed to all such additives; examples being citric acid, malic acid, sucralose, stevia, and anything else that leaves a 'dry residue' from a simple slow vaporiation test (such as on a teaspoon).

One would also need to address the issue of these constituents arriving not just in the mouth and throat but also (at least to some extent) in the lungs.

~~~

I expect it will be ignored, as ever.

 

Most of our flavoured juices result in confusingly complex GC/MS traces, since we use a lot of natural extracts (and as you say, that includes natural esters,) but a few simple mixtures we've tested for example:

in our PEG400-based Platinum Ice (unflavoured, only ingredients = 94.6% PEG400 and 5.4% nicotine,) we're seeing peaks for tetraethylene glycol, triethylene gycol butyl ether and triethylene glycol monomethyl ether. The tetraethylene glycol might well be a trace from the PEG, but the others are evidently being created by the mix.

In a mixture of PG, VG (20%), menthol (7.5%), nicotine (1.1%), a small peak for pentaethylene glycol monomethyl esters shows up (about 10% the amplitude of the VG peak.) Menthol seems to greatly inhibit the tendency for pinking.

In a mixture of PG, VG (20%), PEG400 (10%), vanillin (5%), nicotine (0.8%), small peaks for vanillin propylene glycol hemiacetal (C11H16O5), pentaethylene glycol butyl ether(?), and pentaethylene glycol monomethyl ether(?) show up (each < 10% the amplitude of the VG peak.) Vanillin makes juices pink at the drop of a hat!

I'm not a professional chemist myself, but ours concur the results are consistent with esterification after mixing. We haven't yet (but plan to once we have the inhouse GC/MS up and running,) run repeated tests on samples as they age, and exposed to different factors (light, heat, oxygen,) to compare the results over time. We don't have a lot of time for pure research (production has to be our priority, of course,) but I think the results will be very interesting

 

Oh, man, now THAT would be really interesting! Take a spectrum at set time intervals, plop it all into a spreadsheet, and plot % vs time and get kinetics for each reaction: nic oxidation, esterifications, etc. Of course you may need a grad student to do it all, but that would be seriously cool and useful data...and likely publishable.

 

Even more interesting would be to see what is the mix post-heating/vaporisation. That's where potentially harmful stuff might show up.

Pass through a carto and condense the resultant vapor; compare with liquid-in.

Then again, one can see why those in the industry might not want to go there.

 

Such a study has been done, poorly I might add - as the device was activated in an un natural position.

 

Is that the Flavourart study? I think the subsequent tests showed the excessive puff count (120 puffs from a standard 510 cartridge) may have compromised it more. Repeated with 50 puffs on one flavour they got completely different results. See notes towards the bottom - Protocollo ClearStream - Flavourart. La sartoria degli aromi

 

There have been a few studies but they all had major weaknesses.

I am hoping, and half-expect that the toxins found (I'm sure there will be some) will be at insignificant levels; but I've not seen a convincing study so far to provide real evidence one way ot the other.

Flavorings and additives such as acids and sweeteners will be the main source of concern (if any).

People worry about trace extraction xhemicals and such but don't realise the big difference between solubility and vaporisation, digestion and inhalation.

The concerns are :

1) what toxins might be created by the heating

2) what hazards are presented by inhaling the constituents (whether vaporised cleanly, thermal decomposition products or non-vaporisable constituents misted into the vapor)

Until we know more, the advice must be inhale into the lungs as less as possible*. I would suggest also avoiding addd sweeteners (though ethyl malto is ok, afaik), colors, acids; and anything that looks dark. If a liquid causes cartos to lose performance/die early - that's a bad sign.

There probably are not any big dangers in vaping (but we can't say for sure), but even minor ones could be significant if repeated day after day.

* even as regards VG and PG this is wise i think.

 

Good point - always keep your vaprisation element moist.

 

Happy I found this sub-forum - while still a really newbie noob, I am enjoying these chemical discussions way more than I ever enjoyed chemistry in school . So much that I'm seriously considering digging up my old high school books or maybe trying to find some actual chemistry textbooks...

I recently bought 3 different nic-strengths of a flavoured Hangsen liquid (from Liberty Flights, I don't know if they mix from Hangsen concentrates or buy liquid ready mixed to strength from China).
The strengths were 0mg/ml, 14mg/ml and 24mg/ml.

The strongest was very pink, the 0mg was totally clear. The 14mg in between.

My first thought was that the pink was actually a safety precaution, added to make it easy to identify nic-strength (and crucially zero nic - you would NOT want to ship nic liquid to a customer ordering no-nics!) by sight.

Naturally I have no idea what the colourant might be, but seeing these three small bottles (same flavour) side by side my thoughts immediately went to the use of things to colour or smell-ify things like cooking gas, gasoline, various non-drinkable alcohols etc.
The pink is also *very* potent (I mixed some of the 24mg with colourless base and the colourless no-nic liquid).

If this is a deliberate thing, I actually wouldn't mind such an indicator in my base nic. Would be very practical to be able to distinguish the strength of my mixes just by looking at the colour of the liquid (I don't always want the same nic strength).


Can I ask a stupid question? Well, I will anyway...

When nicotine oxidizes and takes on that yellowish tinge, does that mean that the oxidized part of the nic is no longer available for the body to absorb? IE that the *effective* nicotine strength of the solution is diminished?

And a bit related (yes, I'm having trouble hitting the Post-button already): I am guessing that this yellowing is at least a little bit related to the yellowing of wallpapers etc in rooms where there has been a lot of smoking, and the "nicotine yellow" fingers (and sometimes moustasches) that some old heavy smokers seem to get?

Lots of that is probably from tar, not nicotine. But back when I used an airpurifier that required regular cleaning in my smoking room (now I use a small ozone machine instead - yes I know the dangers, yes I am careful! no, I don't run it all the time! - which is much better and works on virtually *any* smells), the gunk I would wash out of the electrostatic-filter could be roughly divided into three parts:
- miscellanous particles (dust and pollen),
- black particles (sometimes quite large, and also present if I hadn't been home and smoking, so seems to also have been from traffic outside (first floor, busy street, window often open)), and
- brown very smelly stuff - no particles large enough to be seen with the naked eye.

Now when I have handled a nic base-liquid (only 36mg/ml), I would say that the smell of the nasty brown "soup" was not only "particularly nasty old tobacco", but actually had a strong component of that "wet dog" or "fishy" odour of nicotine. (This is such an *interesting* smell/taste IMO. I have a really hard time picking it out of (cured, cigarette) tobacco but suspect it is there. Trying to sniff an ashtray for it mostly makes me confused - I should have some non-cigarette ashes to compare with to be able to say for sure*.)

Oh, that's another question: How does oxidation affect the smell of nicotine?
(I guess I could actually test that one fairly easily by putting a small amount of my base liquid on a saucer and into a cupboard with my ozone generator for a few hours.)

P.S. Dear Mods, I hope I am not too far off topic here. In my defense I would like to say that learning and understanding about the chemistry of nicotine and e-liquids, and easily visible and smellable indicators in general is VERY important for QC in the home.


(* I have a freakish sense of smell; a major contributing factor to my smoking so much for so long. The first week vaping and just cutting down to "only" 10 cigs a day was absolute torture smell-wise, and between this problem and the other nice stuff in tobacco (WTAs), I wonder if I will ever totally quit. I truly do not understand people who *want* a better sense of smell; it is true that it is a sense that habituates fast, but in a shopping mall or on the bus or the street that doesn't really help because new smells are coming at you all the time. So I may sound as weird as I actually am, but I do try to utilize this handicap and make something interesting of it - hence the wacky ideas of comparing smells of different ashes...)

 

Now this is extremely interesting, but makes my observation about the Hangsen liquid being clear at zero nic but very pink at 24mg/ml quite confusing. The flavour in question is a tobacco flavour (D'Doff), but it does have very clearly "taste-able" components of dried fruit, chocolate and vanilla.

Or do you mean with the above that vanillin in combination with nicotine makes juices pink? Hmm, I could actually test this: if I mix a few drops of colourless Hangsen flavour with a colourless (or close to it) nic base and it turns pink...

 

Tona, vanillin is only one culprit to said color changes and it is not restricted to doing so only when mixed with nic ;-) If a component of a flavoring changes color, it will generally do so without being mixed with other components, though I'm sure there are also combinations of components that can cause a more significant change in color than any of the individual chemicals by themselves. Of course, I have no examples for you on that last statement, just a possibility

 

Oh, and one thing I can suggest for why your three liquids are different colors is perhaps they aren't all the same age or one the pink one may not be sealed quite as well, allowing it more exposure to oxygen

 

Thx, Killjoy1.

I did go ahead and mixed a bit of the uncoloured no-nic juice with my own 84/16 PG/VG 13mg/ml nicced juice, and absolutely nothing happened (except eventually a very pleasant vape ). I let the mix (2-3 drops of the no-nic mixed with 1.5ml of my unflavoured base in a clear syringe, no extra air inside it) rest in a well lit place for about 2 hours, no change in colour from the very very faint yellowish tinge my base naturally has.

So no vanillin (if one wanted to use vanillin in DIY flavourings (which I might well want to, since I am one of the weirdoes that actually prefer vanillin-flavoured "vanilla sugar" to the genuine thing), what would be the best form to buy it in?) in that flavour.

I would still tend to believe that this pink is deliberate.