Effects of Heat on Nicotine Degradation

Published by mikepetro in the blog mikepetro's blog. Views: 6465

I want to determine the best bath temperature for speed steeping ejuice via a hot water bath. I want to know the effects of heat on Nicotine concentration, i.e. am I sacrificing potency, and if so how much.

Here is the Test Protocol I am using.

  • Make a large batch of 50/50 PG/VG with ~4% nic, no flavoring or other dilutants.
  • Fill four 1oz Boston Rounds with this mixture.
  • Mark one bottle as the "Control Sample" and set it aside.
  • Mark each of the other 3 bottles with 125F, 150F, and 175F.
  • Put each bottle in a hot water bath (crock pot) for 8 hours at the specified temp.
  • When all batches are complete pull three 5ml samples from each of the four bottles and titrate them, using the average of the 3 titrations as the test result. If any given test result is more than 10% different than the other two, throw it out and redo it as it was probably inaccurate.

To test the nicotine levels I use the following protocol.

  • Rinse Erlenmeyer flask, and syringes, with distilled water
  • Using a syringe measure exactly 5ml of sample into the flask
  • Add ~20ml distilled water (precision not required because water has a neutral ph)
  • Add 3 drops of bromothymol blue pH indicator per ml of sample (more if nic levels are expected to be high) and swirl to mix. In this case 15 drops.
  • Using a 10ml Class A Burette, dispense a slow stream of 0.1N reagent grade hydrochloric acid into flask (swirling flask continuously) until color starts to change to green.
  • Slow stream of 0.1 N HCL down to a drop and continue adding until color changes to yellow, swirling flask after each drop.
  • Note how much HCL was consumed
  • Multiply HCL consumed by 16.223
  • Divide result above by the sample size, in this case 5
Accuracy is affected by sample size, reagent concentration, visual cues of color, visual judgement of syringe level, and technique. I use a larger sample size, and a weaker reagent, for higher accuracy. I estimate my accuracy at +/- 2% or better, hence the reason for testing 3 samples and averaging them, further reducing the margin of error.

Test results are in:

Control Sample: 36.01 mg/l
125F Sample: 35.69 mg/l
150F Sample:
33.09 mg/l
175F Sample:
32.12 mg/l

So it was clear, heat degrades the nicotine. The effect wasnt too bad at 125F, but at 150F there was an 8% loss, and at 175F there was a 10% loss.

This isnt the whole story though, take a look at the conversation I had with a chemist. The layman's version is that the heat can turn nicotine alkaloids into different alkaloids, ones that would still test positive as nicotine in a titration test but might not have the same stimulant effect on the human body.

The samples:

The Crock Pot heating up, controlled by a Sous-vide controller (accurate to 1/10 of a degree):

The Titration apparatus:

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