How about the possibility that oxidised nicotine - it does happen slowly after a bottle has been opened, and in the cart, and presumably at heat time too - might still be at least somewhat active. Any thoughts on that?
Any interest in determining nicotine--by DVAP
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Kinabaloo, oxidized nicotine, always some possibility there!
exogenesis, that graph is interesting.
Due to the pH range shown, the nicotine has to be in a system with stronger acids and stronger bases to permit the overall pH range shown. It is only natural that at lower pH, the freebase would decrease (salt formation).
I'm in a bit of a haze right now as I've not really thought much about it. It's probably important to remember that a solution of nicotine/water or nicotine/PG is not basic in the inorganic sense of an excess of free hydroxyl ions. With organic bases that own their basic behavior to basic nitrogen, you're looking at a nitrogen atom in an aromatic ring that has a lone electron pair acting outside the aromatic system in a non-delocalized fashion (so by virtue of the electron pair, not by dissociation into free hydroxyl ion). I'd expect nicotine sulfate (for example) as a salt in solution to have a pH somewhat less than 7 (as we're looking at a salt of a strong acid/weak base) So in the absense of any significant acidic species, I'm having difficulty seeing nicotine as anything but a free base.
That sound you're hearing, it's rust crackling off my brain and I could have overlooked something really simple.
exogenesis, that graph is interesting.
Due to the pH range shown, the nicotine has to be in a system with stronger acids and stronger bases to permit the overall pH range shown. It is only natural that at lower pH, the freebase would decrease (salt formation).
I'm in a bit of a haze right now as I've not really thought much about it. It's probably important to remember that a solution of nicotine/water or nicotine/PG is not basic in the inorganic sense of an excess of free hydroxyl ions. With organic bases that own their basic behavior to basic nitrogen, you're looking at a nitrogen atom in an aromatic ring that has a lone electron pair acting outside the aromatic system in a non-delocalized fashion (so by virtue of the electron pair, not by dissociation into free hydroxyl ion). I'd expect nicotine sulfate (for example) as a salt in solution to have a pH somewhat less than 7 (as we're looking at a salt of a strong acid/weak base) So in the absense of any significant acidic species, I'm having difficulty seeing nicotine as anything but a free base.
That sound you're hearing, it's rust crackling off my brain and I could have overlooked something really simple.
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The bound or protonated nicotine molecule can be described as a salt even in solution? What happens when heated? This salt is stable enough to stay intact, not vaporise and just ash on the heater coil? Or ...?
As for the oxide - it depends whether the site of oxidation is the active group. I'm just trying to determine if a juice with substantial oxidation of the nicotine is still active / worth vaping.
The question comes down to... does the oxidation product still key to the nicotinic acetylcholine receptor in the brain? Since similar tobacco alkaloids such as nornicotine have some activity, I'd guess that there ought to be some activity.
Don't ask me how receptor keying in the brain works.. I really don't know! I never did take biochemistry, so it's a discipline that I struggle with.
I think I made an oops with mister's post a couple days back. While pyruvic acid is not optically active, and the pyruvate dehydrogenase enzyme handles it just fine, it's not the pyruvate dehydrogenase enzyme that acts upon propylene glycol but one (or more?) alcohol dehydrogenase enzymes, and these enzymes likely do have a better time with one of the PG enantiomers (I think they work better with the L than the D).
I suppose the route to optically pure L-propylene glycol would be via hydration of optically pure L-propylene oxide. Wanna guess what that would do the price? Hint, don't guess, "make it lower".
I suppose the route to optically pure L-propylene glycol would be via hydration of optically pure L-propylene oxide. Wanna guess what that would do the price? Hint, don't guess, "make it lower".
I think I recognise some of the concepts from Uni chemistry lectures
But to paraphrase, are you saying that possibly at >pH7 it's all effectively
free-base (or equivalent), due to the weakness of the organic 'base' ?
I did research (ok, google) this a bit but found almost nothing. Doesn't seem to be a natural source for PG as there is for VG.
Yes, the L form is usually the natural / body useful one (?) The two forms can have different effects. Used to know all this from vitamin / nutrition study years ago.
Technocrat posted (click here for that post) that the cheapest source he'd found for L PG was $40US/ml. Yikes. Not gonna be vaping that stuff!
The article I linked to in that thread (click here for the article) says at the end of a paragraph which describes how racemic PG is metabolized:
"As a result of the stereospecific preference of mammalian alcohol dehydrogenase and aldehyde dehydrogenase for L-propylene glycol, this stereoisomer is cleared most rapidly, and it has been suggested that neurologic dysfunction occurring in propylene glycol toxicity is caused by the accumulation of D-propylene glycol and D-lactate."
Then there's the similar 1,3-propanediol (PG is 1,2-propanediol). By virtue of lack of an asymmetrical carbon, 1,3-propanediol is optically inactive.
[A side note: d and l are abbreviations for the direction that plane polarized light is rotated when viewed through a solution of an optically pure enaniomer, dextro-rotatary (right/clockwise) versus levo-rotatary (left/counterclockwise). There are conventions in naming, +, -, d, l, D, L, as well as R and S enantiomers. Honestly, I need a scorecard to keep them all straight, so I seldom bother to try].
Did some reading, and it turns out that the enzyme 1,3-propanediol dehydrogenase acts upon 1,3-propanediol in the presence of nicotinamide adenine dinucleotide (NAD+) which is abundant in cells to produce reduced NADH (reduced NAD+), 3-hydroxypropanal, and a hydrogen ion. Lactobacillus reuteri (L reuteri) which is present in our digestive systems will act on glycerol to produce 3-hydroxypropanal as well, and the molecule appears to be considered benign.
1,3-propanediol boils a bit higher than PG, 210°C vs 188°C, but not that much higher as to make vaping it a problem.
1,3-propanediol is likely a better vaping base than 1,2-propanediol (propylene glycol) due to it's single step metabolism to a benign product (3-hydroxypropanal). While 1,2-propanediol also metabolizes to a benign product (pyruvic acid), evidence has been suggested that one of the stereoisomers may be harder to metabolize to pyruvic acid. My conclusion is that I will continue to vape 1,2-propanediol (PG) until someone a lot smarter than myself convinces me that I haven't missed something important!
Here's the summary for propylene glycol (1,2-propanediol)
As produced industrially, propylene glycol is a racemic mixture of the d and l enantiomers.
It's been suggested that alcohol dehydrogenase enzymes are better at metabolizing the L enantiomer to benign pyruvic acid.
We are left, potentially, with a problem with difficult to metabolize R-propylene glycol in our systems.
Propylene glycol (1,2-propanediol) boils at 188°C, 22 degrees lower than 1,3-propanediol.
Here's the summary for 1,3-propanediol
1,3-propanediol is optically inactive, and the enzyme that acts upon it does not have to deal with an enantiomer pair.
1,3-propanediol metabolizes in a single step to 3-hydroxypropanal, which (from everything I can find) the body is well equipped to handle.
1,3-propanediol boils at 210°C, 22 degrees higher than propylene glycol (1,2-propanediol).
[A side note: d and l are abbreviations for the direction that plane polarized light is rotated when viewed through a solution of an optically pure enaniomer, dextro-rotatary (right/clockwise) versus levo-rotatary (left/counterclockwise). There are conventions in naming, +, -, d, l, D, L, as well as R and S enantiomers. Honestly, I need a scorecard to keep them all straight, so I seldom bother to try].
Did some reading, and it turns out that the enzyme 1,3-propanediol dehydrogenase acts upon 1,3-propanediol in the presence of nicotinamide adenine dinucleotide (NAD+) which is abundant in cells to produce reduced NADH (reduced NAD+), 3-hydroxypropanal, and a hydrogen ion. Lactobacillus reuteri (L reuteri) which is present in our digestive systems will act on glycerol to produce 3-hydroxypropanal as well, and the molecule appears to be considered benign.
1,3-propanediol boils a bit higher than PG, 210°C vs 188°C, but not that much higher as to make vaping it a problem.
1,3-propanediol is likely a better vaping base than 1,2-propanediol (propylene glycol) due to it's single step metabolism to a benign product (3-hydroxypropanal). While 1,2-propanediol also metabolizes to a benign product (pyruvic acid), evidence has been suggested that one of the stereoisomers may be harder to metabolize to pyruvic acid. My conclusion is that I will continue to vape 1,2-propanediol (PG) until someone a lot smarter than myself convinces me that I haven't missed something important!
Here's the summary for propylene glycol (1,2-propanediol)
As produced industrially, propylene glycol is a racemic mixture of the d and l enantiomers.
It's been suggested that alcohol dehydrogenase enzymes are better at metabolizing the L enantiomer to benign pyruvic acid.
We are left, potentially, with a problem with difficult to metabolize R-propylene glycol in our systems.
Propylene glycol (1,2-propanediol) boils at 188°C, 22 degrees lower than 1,3-propanediol.
Here's the summary for 1,3-propanediol
1,3-propanediol is optically inactive, and the enzyme that acts upon it does not have to deal with an enantiomer pair.
1,3-propanediol metabolizes in a single step to 3-hydroxypropanal, which (from everything I can find) the body is well equipped to handle.
1,3-propanediol boils at 210°C, 22 degrees higher than propylene glycol (1,2-propanediol).
Indeed.
In fact both of you.
I did a little research into possible alternatives to PG some time ago (May) :
These are intriguing because they are said to produce a more dense and longer-lasting fog (in discussion of fog machines); this could enable less to be used to attain the same level of effect (and should also dissolve nicotine well):
* DiPropylene Glycol (DPG) BP 230C Dipropylene glycol - Wikipedia, the free encyclopedia
Might not share allergy issue with PG. Another possibility likely to produce fog is TriPropylene Glycol (TPG) BP265C Tripropylene Glycol Regular Grade (TPG) though DPG looks the better of the two
and
* TriEthylene Glycol (TEG) BP 285C Triethylene glycol - Wikipedia, the free encyclopedia (Although DiEthylene Glycol is safer than Ethylene Glycol it is not a safe choice. The Tri looks promising though.)
What's wrong with using PEG-400 ?
Has certain benefits....
freezes at fridge temp - fresher longer ?,
seems to have a different binding for Nicotine than PG or Glycerine
- i.e. doesn't go pink (which indicates what?)
Has certain benefits....
freezes at fridge temp - fresher longer ?,
seems to have a different binding for Nicotine than PG or Glycerine
- i.e. doesn't go pink (which indicates what?)
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I'm saying that my acid/base chemistry could stand some brushing up with a big-bosomed tutor.
In a system of water/nicotine, or PG/nicotine (PG has a really high pKa and we all know about water), what aside from the protonation fairy is going to act on the electron pair hanging off the nitrogen atom in the ring?
It is the affinity of the nitrogen's electron pair for a proton that makes nicotine act as a base in the first place.
Again, unless that sorely needed tutor shows up to help me with my long disused recollections of acid/base chemistry, I can't see how nicotine can be anything but free base in a solution that doesn't possess any otherwise unbalanced proton population.
I suspect a slight decomp issue.
But if it's more efficient at releasing nic into the bloodstream ... notice that at all ?
As for any of these possibilities, it all must come down to metabolism. Both major pathways, and also potential minor pathways.
I wish I could quote metabolic stuff off the top of my head, but I've got to look it up.
A lot of the discussion from which this concern arises is nicotine in tobacco leaf, not a fairly pure solution; so you could well be right.
With ciggys, nic salts can arrive in the lung carried on ash. Whereas with vaping, it should all be freebase. Which still leaves the question of the inefficiency; seems that the solvent could be the prblem and perhaps exo has a point re PEG.
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Possibly, I did feel (subjective) that I get a better/quicker 'hit' with very high
strength PEG juice than same strength but PG or VG,
might have been my expectations/imagination though.
But has a less 'smoky' vapour than PG.
Don't know how PEG metabolism goes at all,
probably far less info available for that than for PG.
I want a big bossom'd tutor as well, got any spare?
The interesting thng about PEG is that is is metabolically pretty much inert. And chemically, as Exo alluded.
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