Decomposition of VG to acrolein

[jangler]

Thanks Kinabaloo, so one of the warning signs would be the burning taste? I have experienced that, especially with primer liquid found in new atty and every now and then during when the atty starts to feel hot, but that could just be the batting. (not that this is any safer)…

I don’t cut more that 50% VG, more like 10% just for increased vapor. So I guess I’m mixing well within safe parameters? I wonder if there are other forum members who could share their experience with their mods using VP, whether they experience burnt taste more, less or nothing out of the ordinary. I’m assuming the mods do run hotter?

Thank you for guidance and everybody’s contribution. This forum is priceless.

[kinabaloo]

Well, I'd say an analog tastes much worse than the 'bad smell' If not a menthol anyway.

Whatever the cause, the bad smell is not a good sign; but it doesn't keep me awake at night.

The mods primarily aim to address longer battery life. Then style. Then sometimes more vapor.

I know there are acrylamides formed whem i toast a piece of bread, but I still eat it. Maybe I should eat something else instead, but I am going to die anyway one day and I can't prevent it no matter what, so I don't want to spend the time I have worrying too much, especially as stress is a certainly bad for health.

Everything has its pros and cons - even spinach (or anything else one could mention, even exercise); it's all about moderation and variety ...

[Sun Vaporer]

Intellicig had their liquid tested with a specific test for acrolein and none was found. Vaporiser temp was found to be up to 130C but test was done up to 300C. Report
Alan.

Letzin--I saw this as well and it confirms for me that there is no issue with acrolein---Sun

[exogenesis]

While not unduly concerned about acrolein during 'normal' vaping of VG,
the 'burnt taste' due to a dry hot coil is something to think about.

My problem with these reports is they are attempting to detect a very
small amount of acrolein in a vast amount of potentialy obscuring bulk
liquid/vapour (VG).

i.e. the far easier test for a small amount of just acrolein
(in say just air or water) would probably give definitive quantitative results.

I think that leads to the slight ambiguity of phrasing like:

...test for the presence of posible acrolein structures which at
the time of writing we are pleased to report have not been identified

Which does not exactly state that there were no acrolein peaks seen
in GC/MS & other test-methods,
just that possibly they could not 'detect' acrolein in the melee of signal
from the bulk liquid (i.e. signal noise may swamp the small target peak).

If that could be clarified by any of the testers, it would be somewhat useful.


There is a colorimetric acrolein-specific 'wet test' I've seen,
but not sure how sensitive it is,
I possibly might get the reagents & investigate a bit further.

[surbitonPete]

I don't have the greatest sense of smell anyway but for some reason I am convinced it's probably something to do with acronolyn when I get that really horrible chip fat 'taste' and that usually only happens with a gunky coil that I have vaped a bit too dry. It never happens with a fairly new coil. I doubt if their tests recreated those conditions.

[ChainSmkr]

A quick search yielded decomposition temperature for PG as >350C far higher than its boiling point of 188C so although the decomposition products are hazardous, it is extremely unlikely to occur at all in an atomizer.

In contrast, VG begins to decompose before reaching its boiling point.

Oh yeah! I think I do remember that from another thread. Thanks kinabaloo.

[Sun Vaporer]

While not unduly concerned about acrolein during 'normal' vaping of VG,
the 'burnt taste' due to a dry hot coil is something to think about.

My problem with these reports is they are attempting to detect a very
small amount of acrolein in a vast amount of potentialy obscuring bulk
liquid/vapour (VG).

i.e. the far easier test for a small amount of just acrolein
(in say just air or water) would probably give definitive quantitative results.

I think that leads to the slight ambiguity of phrasing like:


Which does not exactly state that there were no acrolein peaks seen
in GC/MS & other test-methods,
just that possibly they could not 'detect' acrolein in the melee of signal
from the bulk liquid (i.e. signal noise may swamp the small target peak).

If that could be clarified by any of the testers, it would be somewhat useful.


There is a colorimetric acrolein-specific 'wet test' I've seen,
but not sure how sensitive it is,
I possibly might get the reagents & investigate a bit further.

I get that same taste with PG--so where is the corellation to Acrolein? Or are you trying to say that PG will create acolein as well. I simply do not see it. Again the report just out showed no trace of acrolein while using VG so I would like to see a report to the contray before I would give this contention merit IMO-------Sun

[exogenesis]

No, I'm not in the 'assuming there is acrolein' camp,
& PG won't decompose to acrolein as far as I know.

Good point though about the burnt taste with PG, but are you talking about:
pure PG (as in your testing),
or a commercial PG-only e-liquid,
or a 'normal' commercial PG e-liquid (that's got quite a lot of VG in it) ?


Actually I'd assume that you'd expect some 'burnt' taste with practically any organic
liquid passed over a very hot coil, really the taste is not the important factor.
But it obviously has connotations here :
- perceived risk & all that (whether erroneous or not),
especially with all this communities 'attention' on acrolein,
even though other components (in less 'pure' e-liquids) might be
just as worthy.


It's very good that these tests are being done, so there's no
'take the word of the manufacturer' distrust going on,
kudos to them for having the tests done.
But with that comes the whole reason for the testing
- to attempt to clearly show absence/presence/amounts of the components being tested for.
Otherwise what's the point?


This testing was done aiming at the major ingredient components (glycerine/nicotine/flavour),
but there's no specific test to confirm/deny acrolein presence in there.


In the report it would have been good to see a GC/MS
calibration-standard for acrolein, so you could point to a place on the
'Smoked Cartridge' ' test's GC (& MS) traces & be able to say 'definately no acrolein peak'.

Unfortunately that 'Smoked Cartridge' GC trace was possibly somewhat
too noisy & complex for that anyway?
But it shows there was certainly a substantial signal for components between
the clear argon and glycerol/glycerol-like peaks.

This signal could be obscuring, or possibly even be acrolein
or other acrolein-like decomposition products.
And the MS traces for this sample are not given, either MS was not done on
this sample, or they were not presented due to being too confused/difficult to interpret.

Realisticaly testing aimed at specifically measuring acrolein would be needed before you
can dismiss (or confirm) this contention. It's still a possibility.
Personally I'd prefer the facts rather than supposition either way.

But would the manufacturer release that info, if it was confirmed?

Tough choice - pay for an expensive test to potentially show a problem
with your product.

Then again if that testing showed zero, or below acceptable levels,
then everyone's happy.

[kinabaloo]

Acetaldehyde is another potential toxic product of either VG or PG; unlikely but possible. This one actually has a nice(ish) smell (something like apple). Although harmful (possibly carcinogenic even) it also can be found in trace amounts in food when it begins to go bad, and is a metabolite of alcohol in the body (the chemical responsible for the hangover, apart from general dehydration).

My concern is not only about acrolein. And I'm not in a 'camp' or have any agenda; just scientific curiosity.

This interesting paper concerns additives of PG and VG to tobacco. Although tobacco is combusted in a cigarette rather than heated, much of the PG or VG would undergo evaporation as the heat approached it, before being combusted. It found no acrolein with PG, but both did lead to nasties such as acetaldehyde and formaldehyde (though possibly by combustion and be irrelevant in vaping; not sure): http://tobaccodocuments.org/product_...6985-7022.html

It gives a figure of 1% conversion of VG to acrolein in the cigarette; a pretty high value. I would expect the figure to be (perhaps far) lower in the vaping scenario.

If pure PG plus water leaves a deposit, as apparently it does, this is quite a puzzle. Seems UPC grade VG and PG would contain nothing other than water measurable in quanties over ppm so that explanation looks unlikely. Understanding PG in this regard might shed an alternative light on the deposit formation of VG, but at present the mechanism is really obscure if the acrolein route is not the primary route.

All I can suggest for PG (decomposition/reaction) leaving a deposit is that this is catalysed by solder-leeched tin, or by the chromium or nickel of the coil, making something that would not normally be expected occur.

~~~

ps: Comparison of grades of glycerine http://c1-preview.prosites.com/37030...on%20Chart.pdf

[exogenesis]

Re-read that acrolein from glycerol in tobacco smoke,
(& even though it's from Phillip Morris) it's quite enlightening.

Having second thoughts about
'glycerol just being like any burning organic liquid on a hot coil',
specifically probably similar to PG or other carriers...

cos just now observing pure PG vaping on a fresh exposed coil (550mA)
& it seem's to be producing no burnt gunk whatsoever.

We'll see what it's like after 20 to 30 ml.

Did SunVaporer post his VG vs PG results?