I thought it would be nice to have this information here for our group.
Guide To E-Liquid, Liquid Strengths MG, & Usage
Usually contains nicotine in a base of Propylene Glycol (PG). Sometime the base is Vegetable Glycerine (VG) or PolyEthylene Glycol (PEG, with a molecular weight of 200+). There may also be flavors and aromas.
Propylene Glycol (PG) Vegetable Glycerin ( VG) Polyethylene Glycol (PEG)
- All three are water soluble viscous liquids used in e-cig liquids to deliver nicotine and/or flavors.
- They Produce the vapor and provides a similar sensation to inhaling tobacco smoke.
- They are humectants (attract moisture) and may dry your throat and cause it to feel sore. Drinking more fluids will help.
- Some people experience allergy-type symptoms to one or all three.
If so, stop using and/or switch to one of the other two and see if the symptoms go away. If severe, it is recommended that you see your doctor.
Propylene Glycol (PG)
Propylene glycol - is:
- Most commonly used, more throat hit, more flavor.
- Slightly sweet and colorless.
- USP approved propylene glycol is used in cosmetics, toiletries, food colorings, cake mixes, salad dressings, soft drinks and more.
- It is also used in the smoke / fog machines found in theatres and nightclubs.
Vegetable Glycerin ( VG)
Vegetable Glycerin also known as Glycerol - is
- Slightly thicker and sweeter.
- Produces more vapor.
- USP approved glycerin is used in 1500+ applications as an additive to food and drink.
- Glycerin can be found in the baking or craft areas in grocery, hobby and department stores. It can also can be found in pharmacies.
Also known as: Glycerin, Glycerine, or Glycerol.
Pharmaceutical grade glycerin is named Glycerin, USP.
Without this exact nomenclature it is not pharmaceutical grade (any variation indicates that it is not regulated, and therefore uncontrolled). In the UK it is termed Glycerine, BP.
In the United States it is recommended that you only use USP approved propylene glycol and glycerin.
If you live outside of the U.S., use only pharmaceutical approved Glycerin and/or PG.
Polyethylene Glycol (PEG)
A non-toxic compound that is used in pharmaceutical compositions and food additives.
PEG 400 - Wikipedia, the free encyclopedia
PG and glycerin have also been studied for inhalation safety due to their common use on stages around the world for fake smoke/fog machines.
EPA PG reregistration approval document:
The study that showed PG safe as a base for inhaled cyclosporine by lung transplant patients:
Mary Ann Liebert, Inc. - Journal of Aerosol Medicine - 20(4):417
E-Juice Handling Care.
E-juice contains nicotine, whch is in fact quite poisonous in anything other than tiny amounts, so take care not to get it on your skin. If that does happen, rinse off straight away.
The mg stated on analogs is what is typically absorbed.
The mg stated on juice is what is in the liquid. Only about 1/3 of that is absorbed, possibly a fair bit lower (some tests have said as low as 10%; but the maximum is probably 40%). Let's say 30%*.
A box of 20 cigs gives aboout 20mg nicotine (20 x 1mg).
2ml of 36mg liquid will give about 2 x 36 x 0.33 = about the same : 20mg absorbed.
So 1 box of cigs is roughly equivalent to 2ml of 36mg juice or 3ml of 24mg juice.
510-t tanks can hold about 0.8ml (at most); so 2ml is about 4-5 carts.
(Note that some other carts are bigger).
So if you have just vaped 2ml of 36mg liquid and calculated that as equivalent to 60 cigaretes - don't panic, it is not; it is about 20, perhaps less, in real terms.
* Only about 45% of the nicotine in e-liquid gets into the vapor. Allow for some further losses, exhalation and non-absorption and 30% is a reasonable estimate.
Let Us Elaborate Further On Nicotine:
Some studies stated that vaping provides only about 10% of the nicotine compared to smoking - is this figure wrong?
Probably, yes. While I am quite sure that many people get less nicotine than they think they do, it is surly not 10% - e-cigarettes just wouldn't work at that level.
I think a majority actually do step down their nicotine intake when switch to vaping. Some 60 a day former hardcore smokers are now quite happy with, say, 18mg liquid (actually quite low in real terms).
And this might be a better level - not because it is lower per se, but because with smoking the activity is probably excessive for various reasons, such as needing to finish a whole cigarette, only having a short break outside before getting back to the office promptly, and a host of other similar factors (generally summed up as needing to fit in as much as possible because not allowed to partake as and when desire).
What's the likely explanation for the erroneous 10% figure?
Only about 40-45% of the nicotine in e-liquid makes it out of the atomiser and into the vapor. I cut that vaporised nicotine by 25% as an approximate figure for that unabsorbed/exhaled to give 30% absorbed. Still 3x the 10%. So something is being missed in those (not many) 10%-ish studies.
One possibility is that it misses the slower rate of absorption by measuring effect of one 10 minute session of vaping at a fixed point; missing the cumulative value. That's always been my prime explanation. Alternatively, but less likely, some of the nicotine is missed in the analysis somehow - it is there but not being measured; the form may be different; and while it sounds silly to say that perhaps the nicotine recombines with glycols in the blood, perhaps 'something' like this is occurring. But the absorption rate is likely the answer.
How can e-cigs be being successful if the nicotine is much lower than what people were used to?
Somehow that 30% figure still allows e-cigs to be successful for most people (though not all - some can only stick it by increasing the nic substantially, to match what they have been used to). For that majority, what I think happens is: initially, and because of the novelty, the shortfall is compensated by increased volumes - vaping much more than used to smoke (more puffs); so the total nicotine per day (rather than per puff) is raised to near the accustomed value. This pattern of use subsides gradually, slowly enough for the body to adjust (perhaps with a need for a stronger vape in the morning).
So not only have most vapers cut the tar and soot, they have likely also cut their nicotine somewhat too.
How addictive is nicotine?
Related to this is the issue of just how addictive nicotine really is. Perhaps by itself it is not as addictive as generally believed - as evidenced by quite a few people being able to cut their nicotine use to zero in just days or weeks. The really addictive thing could be the combination of nic plus MAOIs (for which biochemistry of this double-whammy makes good sense), with perhaps other factors involved too.
What about the missing buzz I used to feel when smoking an analog?
The 'buzz' that many people feel is missing with e-cigs could be the absence of the nicotine/MAOI 'double whammy', in particular. Even when the nicotine is raised, it doesn't give that special feeling - and this is not about freebase or some other nature of the nic, but the absence of the MAOIs. Alternatively, a slower absorption rate could (at least partly) account for it.
Is the nicotine from vaping really more slowly absorbed?
It is not clear yet, but it is quite likely that this is the case. In the past it had been thought that analog nicotine was faster to the bloodstream (and brain) because it was partly a 'special' freebase (un-combined) form of nicotine; in fact, e-liquid has more nicotine in this freebase form (nearly all). The real reason would most likely be the carrier - with smoking, the nicotine (normally a liquid at room temperature) is carried on tiny particles of ash. With vaping the carrier is a liquid (small droplets of PG or VG in which the nicotine is dissolved (the visible fog of re-condensed vapor).
Not only are the liquid droplets larger than the ash (smoke) particles*, but it is harder for the nicotine to 'escape' the liquid that the ash (the nicotine is sitting on the outside of the ash, so to speak). A further factor comes into play - the smaller size of the particles in analog smoke mean that (much) more of the nicotine reaches the lungs, where passage to the bloodstream is far easier (the barrier is much less here because the haemoglobin of red blood cells in the blood needs to be able to latch onto oxygen from the air; with digestion, absorption of sugars, say, needs to be slower as blood sugar levels need to be tightly controlled, so absorption in the mouth is much slower).
* Smoke particle size : 0.1 to 1 micron; PG mist droplet size : 1 to 5 micron
Drops per ml.
There are approximately 20-25 drops in 1ml.
There are around 5 puffs in one drop, so about 10 puffs per 2 drops. Two drops is the amount most commonly added when dripping, see below.
Average E-Liquid Usage.
A typical user vapes around 3ml / day.
- a 10ml bottle lasts about 3 days.
- a 20ml bottle lasts about 1 week.
- a 30ml bottle lasts about 10 days.
A 16mg juice means 16mg / ml.
- 1 analog cigarette = approx. 1mg nicotine absorbed.
- 1ml of 16mg nicotine juice = 16mg nicotine (about 16 analogs equivalent, potentially).
In practice, some juice is not converted to vapor and some is exhaled or otherwise not absorbed. Average smokers, when changing to vaping, on average find that 24mg satisfies their cravings and allows the successful switch from smoking to vaping.
Many later reduce their juice strength in the following weeks and months.
The enemies of E-Liquid are light and air. So always store away from daylight, preferably in dark containers.Keep it cool too.
Juice that is going bad (oxidised) will get darker. Not a health hazard, afaik, but will give less nic hit and poorer taste. It should be good for a year or two.
Plastic is ok for the smallest bottles (current use).
All the E-Liquid manufacturers recommend refridgeration for long-term storage.
Chemically, there is no reason to think that any changes could occur and the colder temperature would slow both oxidation and microbial activity.
This applies to freezing also. Even super-complex molecules such as DNA can survive thousands of years in freezing temperatures.
There is, however, a precaution. This precaution applies no matter whether storage is in the fridge or not. And it is this:
Spoilage can occur through oxidation and microbial activity. To protect against oxidation, store without air inside the container and make sure the seal is air-tight. Glass and ceramic containers are to be preferred for long-term storage as plastic is very slightly air-permeable.
Microbial spoilage is by far the most likely reason for juice spoilage occuring in a sealed container. As far as we know, juice (with a major component being PG at least) is inherently anti-microbial; this might well not be the case with VG based juices. However, there is a potential scenario that could allow microbial growth - in any air space above the liquid, where water, evaporated from the juice or in the air, can condense on the inner container surface and provide a breeding ground; water preferentially evaporates as it has a lower boiling point than PG or VG.
So when storing long term it is wise to exclude all air. More to eliminate the possibility of microbial activity in condensation than oxidation from the air.