Types of nicotine base liquid
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    Default Types of nicotine base liquid

    A question for the chemists, please.

    What comments could you make about the following three 100% VG unflavored 36mg liquids:

    1. A clear liquid, faint 'wet dog' smell.

    2. An almost clear liquid with the faintest pale yellow tinge, strong 'wet dog' smell.

    3. A pinky-red liquid, faint smell as above.

    I'm just interested in why three liquids can look and smell so different when in theory they are the same thing. Seem to remember that the no-smell liquid has maybe had citric acid added to remove the smell. What are the implications of that? And the red color is remaining reaction compounds from the extraction process. Again, what implications does this have?

    Sorry, but I haven't tested them for nic strength. They seem about right.

    Thanks.
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    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.
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    Thanks Kurt.

    What implications are there to the addition of an acid in order to reduce the aroma - from the point of view of effect on the liquid or effect on the atomiser element (if known). As regards inhalation I won't ask you to comment as that sort of thing is probably speculative.
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    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.
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    Quote Originally Posted by Kurt View Post
    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
    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.
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    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.
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    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.
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    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.
    Last edited by kinabaloo; 11-27-2011 at 02:56 AM.
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    Quote Originally Posted by Kurt View Post
    @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.
    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
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    Quote Originally Posted by Nick O'Teen View Post
    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.
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