Any interest in determining nicotine--by DVAP

[DVap]

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).

[DVap]

Good work, mister.

[kinabaloo]

Originally Posted by DVap

Good work, mister.

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.)

[exogenesis]

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?)

[DVap]

Originally Posted by exogenesis

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'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.

[kinabaloo]

Originally Posted by exogenesis

What's wrong with using PEG-400 ?
Has certain benefits....
freezes a fridge temp - fresher longer ?,
seems to have a differnet binding for Nicotine than PG or Glycerine
- i.e. doesn't go pink (which indicates what?)

I suspect a slight decomp issue.

But if it's more efficient at releasing nic into the bloodstream ... notice that at all ?

[DVap]

Originally Posted by exogenesis

What's wrong with using PEG-400 ?
Has certain benefits....
freezes a fridge temp - fresher longer ?,
seems to have a differnet binding for Nicotine than PG or Glycerine
- i.e. doesn't go pink (which indicates what?)

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.

[kinabaloo]

Originally Posted by DVap

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.

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.

[exogenesis]

Originally Posted by kinabaloo

I suspect a slight decomp issue.

But if it's more efficient at releasing nic into the bloodstream ... notice that at all ?

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?

[kinabaloo]

Originally Posted by DVap

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.

The interesting thng about PEG is that is is metabolically pretty much inert. And chemically, as Exo alluded.