Any interest in determining nicotine--by DVAP

[kinabaloo]

It's quite a stretch. Last time I checked 1 millimole of monoprotic acid neutralizes 1 millimole of monohydroxy base. I don't think they changed the rules on that when I wasn't looking.

I always have the option of analyzing any of this on a high resolution mass spectrometer with the kind of trace sensitivity that boggles the mind. Trouble is that we charge clients sometimes as much as $1300 for an hour long analysis. If I'm found using these things as my personal toys, I'll have a bit of explaining to do. Plus, I still don't have standard reference materials for nicotine, and though suppliers of pure nicotine/nicotine standards would send the stuff to me at the laboratory without question, I would again, have some explaining to do since none of what we do involves nicotine.

Overall, I don't know if I'll actually do half the testing I dream up here, though trying to account for all the nicotine in an auto-vaped cart really sounds interesting about now. Very often, an experiment looks good on paper, but just doesn't work too well in practice, so validation is important, otherwise, the data (and therefore the conclusion) is very likely crap.

The recent FDA found some variation in strength from that labelled but not too far off as i remember.

I can understand about the difficulties.

In case some nicotine is indeed lost through the open-air heating, already begun thinking how this could be avoided or minimised, but I don't so far see any simple way to avoid this - other than by switching to ultrasonic transducer to create a mist (or a hybrid approach in which the misted juice is mixed with steam to achieve some warmth).

My alternative theory for the missing nicotine (not reaching the blood stream) is that the base holds onto it and it is preferentially evaporated and exhaled subsequently (a bit wooly I know); VG in particular is extremely slow to evaporate and is said to have an affinity for nicotine.

 

[DVap]

My alternative theory for the missing nicotine (not reaching the blood stream) is that the base holds onto it and it is preferentially evaporated and exhaled subsequently (a bit wooly I know); VG in particular is extremely slow to evaporate and is said to have an affinity for nicotine.

I don't think your theory is all that wooly. Matrix is everything. Smoke likely carries nicotine without having much of an affinity for the nicotine. PG and VG, on the other hand, as you mention, do have an affinity for nicotine, so your airway is likely in competition with the vapor for the nicotine.

 

[kinabaloo]

I don't think your theory is all that wooly. Matrix is everything. Smoke likely carries nicotine without having much of an affinity for the nicotine. PG and VG, on the other hand, as you mention, do have an affinity for nicotine, so your airway is likely in competition with the vapor for the nicotine.

Good to get a tumbs up on this.

I remember reading how in the first world war, VG was applied to the tips of the ration cigs to make them more palatable. Later, a reduced nic cigarette was trialled using the same idea. Then there's the fact (?), maybe you said it, that VG makes a good nic extraction solvent. Not sure how much this applies to PG though.

Now for a somewhat abrupt change of tack (and I certainly don't want to derail the original thread, but this will be of extremely little interest to most people): I have thought that an interesting alternative to nicotine might be theanine, the psycho-active ingredient in tea, that has both stimulant and relaxing effects. As an amino acid I would guess it will not vaporise, but that ther might be a volatile compound that has the same active group(s). Last time I researched this, next to nothing known about theanine even, surprising as it's been a popular beverage for well over a century. Again, ultrasonic misting might be the only effective way to go. Any thoughts?

 

[DVap]

I'd just drink a good cup of tea.

 

[kinabaloo]

I'd just drink a good cup of tea.

Ok, some more reasoning: if forced to choose between 0nic vaping and nic patches, I think the vaping still wins. I know that the antioxidant benefits of tea are seriously mitigated by adding milk (and adding more than a tiny amount kills the taste too). So I imagine that a vape with some calming theanine in it could go down well.

Although i love coffe, I dont think I want a caffeine vape. The alternative to some psych-active effect wuld for me be strong taste - capsicum, cloves, something like that.

ps: surprised no juice companies have inquired about your dosage testing techniques

 

[BlondieLocs]

Just wondering, has anybody decided to gather the material to do this themselves? Either the full or compact procedure?

Hahahahahahahaha. Whoosh!! (That would be the wind whistling above my blonde head...)

 

[DVap]

Naw, that's just the sound of the topic drifting around a bit.

 

[DVap]

The other day, I checked out Chris Yeltin's website myfreedomsmoke.com

He's got e-liquids for sale at volumes large and small, and the price seemed pretty good, so I bought 60 mL of 48 mg unflavored. It ran me $36.95 plus $5.95 for USPS Priority shipping, so I paid $42.90 for 60 mL of the 48 mg e-liquid.

I don't know the guy, never talked to him, just bought from him this once.

You might be wondering how the 48 mg unflavored liquid from myfreedomsmoke.com tested.

Replicate 1: 45.5 mg
Replicate 2: 46.1 mg
Average (replicate 1 & 2): 45.8 mg
Average % of labeled concentration determined: 95.4%

This is an excellent result. I'll be buying from Chris again.

(If I'm off 5% either way, it could range from 43.5 - 48.1 mg).

This stuff is legit.

 

[Kate51]

Thanks very much, is fascinating! I will add this to my kitchen lab for future reference. It's ok, I need to paint the ceiling anyway!
Just kidding. But this is quite obviously something we all are striving to make sure what we see is what we get. Thanks for your hard work DVap.

 

[DVap]

Thanks Kate.

Geez.. did you really smoke 3 packs a day before e-cigs?

 

[DVap]

Anyone ever wonder why ethylene glycol is considered toxic while propylene glycol is not?

It's all about what happens when the body oxidizes the two molecules.

Ethylene glycol is metabolized (oxidized) to oxalic acid (the simplest dicarboxylic acid). Oxalic acid has an affinity for metal cations, which messes up blood chemisty, and ultimately tends to form insoluble precipitates which gather in the kidneys. In short, the body doesn't know what to do with it, so it does what it can with it, none of which are good.

Propylene glycol, on the other hand, is metabolized (oxidized) to pyruvic acid. The body knows what to do with this stuff. The pyruvate dehydrogenase enzyme goes to work on it, and pretty soon the citric acid cycle takes over, and it's metabolized for energy.

Relax, there will not be a test.

 

[exogenesis]

Very nice work DVap, good to see some informative & practical chemistry analysis here.

But one thing comes to mind, if this is a simple base titration with acid,
then it's measuring only the free-base nicotine proportion of that present.
Wouldn't some of it already be in the salt form, for whatever reason ?
(e.g. from reactions with additives, or even from direct formulation pH-modification).

This is an older post showing the (theoretical / possible) ratio of nicotine free-base/salt with pH
(supposedly this is for smoke, no specific liquid 'matrix', so it's a bit generic).

pH and nicotine

If e-juice intially at pH 8.3 did 'only' contain 60% freebase, then wouldn't the titration
method read 40% low ?

Not knocking you efforts, which are great,
just curious to know


PS, if refrigeration for long term stability was important,
I'd use PEG-400, since it solidifies at ordinary fridge temps (4 ish deg.C),
I'm using a juice with this & it's definately stopped the progressive
'pinking' and 'browning' seen with PG & VG,
although the latter also change much slower when cooled.

 

[kinabaloo]

The other day, I checked out Chris Yeltin's website myfreedomsmoke.com

He's got e-liquids for sale at volumes large and small, and the price seemed pretty good, so I bought 60 mL of 48 mg unflavored. It ran me $36.95 plus $5.95 for USPS Priority shipping, so I paid $42.90 for 60 mL of the 48 mg e-liquid.

I don't know the guy, never talked to him, just bought from him this once.

You might be wondering how the 48 mg unflavored liquid from myfreedomsmoke.com tested.

Replicate 1: 45.5 mg
Replicate 2: 46.1 mg
Average (replicate 1 & 2): 45.8 mg
Average % of labeled concentration determined: 95.4%

This is an excellent result. I'll be buying from Chris again.

(If I'm off 5% either way, it could range from 43.5 - 48.1 mg).

This stuff is legit.

This is important because it shows (in all likelihood though not sufficiently robustly statistically speaking) that your measuring is accurate - and accurate in this range.

The 4% could be explained by oxidation?

Any thoughts on whether oxidised nicotyine could still be psycho-active / become so when heated, or is it permanently lost, usefully speaking, when this occurs in an e-juice?

I'd love to join in with this practically but am seriously short of time (and my science background leans more to physics than chemistry, though i understand titration, no problem).

Even with just the one person out here who might test anything at anytime, it can only be doing us all a big favor (and the companies themselves too, in fact).

 

[Mister]

DVap, thank you so much for your work and your sharing of knowledge about this subject!

If you have the time and an interest in it, there's another subject which I'd love to hear your thoughts about.

It seems that the body metabolizes one stereoisomer of propylene glycol far better than the other. It also seems that all commonly available propylene glycol is racemic, presumably including all that we vape. Do you know of any way to isolate the stereoisomer our bodies are better equipped to deal with? That might make significantly better eliquid. Perhaps an eliquid without negative affects for any user.

There's a thread on this subject if it interests you: http://www.e-cigarette-forum.com/fo...4-enantopure-propylene-glycol.html#post534326

BTW, I'm a layman, please forgive my (probable) misuse of terminology in some of my posts about this.

 

[kinabaloo]

Anyone ever wonder why ethylene glycol is considered toxic while propylene glycol is not?

It's all about what happens when the body oxidizes the two molecules.

Ethylene glycol is metabolized (oxidized) to oxalic acid (the simplest dicarboxylic acid). Oxalic acid has an affinity for metal cations, which messes up blood chemisty, and ultimately tends to form insoluble precipitates which gather in the kidneys. In short, the body doesn't know what to do with it, so it does what it can with it, none of which are good.

Propylene glycol, on the other hand, is metabolized (oxidized) to pyruvic acid. The body knows what to do with this stuff. The pyruvate dehydrogenase enzyme goes to work on it, and pretty soon the citric acid cycle takes over, and it's metabolized for energy.

Relax, there will not be a test.

I could pass this one

Excellent simple yet thorough explanation.

 

[kinabaloo]

Very nice work DVap, good to see some informative & practical chemistry analysis here.

But one thing comes to mind, if this is a simple base titration with acid,
then it's measuring only the free-base nicotine proportion of that present.
Wouldn't some of it already be in the salt form, for whatever reason ?
(e.g. from reactions with additives, or even from direct formulation pH-modification).

This is an older post showing the (theoretical / possible) ratio of nicotine free-base/salt with pH
(supposedly this is for smoke, no specific liquid 'matrix', so it's a bit generic).

If e-juice intially at pH 8.3 did 'only' contain 60% freebase, then wouldn't the titration
method read 40% low ?

Not knocking you efforts, which are great,
just curious to know


PS, if refrigeration for long term stability was important,
I'd use PEG-400, since it solidifies at ordinary fridge temps (4 ish deg.C),
I'm using a juice with this & it's definately stopped the progressive
'pinking' and 'browning' seen with PG & VG,
although the latter also change much slower when cooled.

Exo - i did wonder that too but it would seem from the results that come out right that this possibility doesn't affect the practical results. Be interested to hear from DVap on this - and on freebase generally.

Good to see some confirmation re refrigerating for long-term storage too.

edit: Went back to review the pH-freebase% data; and the change is more dramatic than i had remembered.

http://www.exogenesis.co.uk/FreebaseNicotineWithpH.jpg

 

[kinabaloo]

DVap, thank you so much for your work and your sharing of knowledge about this subject!

If you have the time and an interest in it, there's another subject which I'd love to hear your thoughts about.

It seems that the body metabolizes one stereoisomer of propylene glycol far better than the other. It also seems that all commonly available propylene glycol is racemic, presumably including all that we vape. Do you know of any way to isolate the stereoisomer our bodies are better equipped to deal with? That might make significantly better eliquid. Perhaps an eliquid without negative affects for any user.

There's a thread on this subject if it interests you: http://www.e-cigarette-forum.com/fo...4-enantopure-propylene-glycol.html#post534326

BTW, I'm a layman, please forgive my (probable) misuse of terminology in some of my posts about this.

Very interesting, even if of no practical signifance (no viable source of natural PG and no way to separate the isomers). The body's better handling of one isomer suggests natural selection for the one found in natural foods (yet some random and not always good, yet not disastrous, things get coded into dna too sometimes; like our inability to make ascorbic acid). Juice PG is derived from the petrochemical 'natural gas' so would have both isomers, afaik.

Hope to get some time to look into this later, starting with your link.

 

[DVap]

I think I covered the state of the nictotine freebase vs salt in a previous post. The comment I made was that the presence of other bases would bias the nicotine result high while the presence of acidic components would present a low bias. I selected bromothymol blue as the indicator because it goes yellow at pH 6, and once all base is consumed, the drop past pH 6 with 0.1N acid is rapid. While it's possible to have other tobacco alkaloids determine as nicotine, I can't see why anybody would be acidifying the e-liquid they sell.

I would not assume oxidation as the reason for a 95+% result on the liquid I analyzed yesterday, it can more likely be put down to a) experimental error, or b) that's the real concentration in the liquid.

As for the stereochemistry of propylene glycol, it's the asymmetrical carbon that gives rise to enantiomerism. You'd need an optically pure starting material to synthesize an optically pure single enantiomer of PG.

Metabolically, on it's path from PG to pyruvic acid, I see nothing that would stand in the way of oxidation of either component of the racemic mix to pyruvic acid. Here's the rub, pyruvic acid is not chiral. So I wonder if the body ultimately cares?

 

[kinabaloo]

I think I covered the state of the nictotine freebase vs salt in a previous post. The comment I made was that the presence of other bases would bias the nicotine result high while the presence of acidic components would present a low bias. I selected bromothymol blue as the indicator because it goes yellow at pH 6, and once all base is consumed, the drop past pH 6 with 0.1N acid is rapid. While it's possible to have other tobacco alkaloids determine as nicotine, I can't see why anybody would be acidifying the e-liquid they sell.

I would not assume oxidation as the reason for a 95+% result on the liquid I analyzed yesterday, it can more likely be put down to a) experimental error, or b) that's the real concentration in the liquid.

As for the stereochemistry of propylene glycol, it's the asymmetrical carbon that gives rise to enantiomerism. You'd need an optically pure starting material to synthesize an optically pure single enantiomer of PG.

Metabolically, on it's path from PG to pyruvic acid, I see nothing that would stand in the way of oxidation of either component of the racemic mix to pyruvic acid. Here's the rub, pyruvic acid is not chiral. So I wonder if the body ultimately cares?

I believe that some recipes do add citric acid (not sure why as it would not vaporise; preservative perhaps); not enough to alter the pH too much though one would imagine. Would be nice to know the pH of the anomolous juice though.

RE oxidised nic - should be very little in anopened juice; i guess that your point. Once oxidised could it still be active/activated?

 

[DVap]

I believe that some recipes do add citric acid (not sure why as it would not vaporise; preservative perhaps); not enough to alter the pH too much though one would imagine. Would be nice to know the pH of the anomolous juice though.

RE oxidised nic - should be very little in anopened juice; i guess that your point. Once oxidised could it still be active/activated?

I'm not convinced that a solution equi-molar in citric acid and nicotine (both weak) would neutralize in the same manner a strong acid will neutralize nicotine.

If there were citric acid, the question would be how much? My next question would be why?

Citric acid decomposes at 175°C into water and aconitic acid (the body can handle it) which itself decomposes around 200°C with acrid smoke. The temperature at the business end of an atomizer (especially one on the dry side) would likely easily reach 175°C (347°F). In short, citric acid, at a glance, isn't something I'd want in my e-liquid.

Back to the possibility that formulation can mask nicotine in a titration. I've already conceded that as a possible stumbling block. I can envision a simple cleanup using extraction of e-liquid from basic solution, evaporation of the solvent, and addition of water to a known volume to eliminate any possibility of bias from acidic species in the e-liquid matrix. The recovery should be essentially 100%, and result in a higher titration if (and it's a big if) a biasing acidic species was present in the first place.