What is free nicotine - and why it decides your dose
The chemistry in one line
Nicotine has a pKa near 8.0. At pH 8.0 roughly half of it is free; at pH 7.0 only about 9%; at pH 9.0 around 91%. Measured pouches span roughly pH 6.9 to 10.1, which is a free fraction from about 8% to 99%.
FREE NICOTINE AT pH - 6 MG POUCH
Henderson–Hasselbalch with nicotine pKa 8.01. Slider values are illustrative; product pH values elsewhere on this site are labeled measured or estimated.
What that looks like in real products
Three US pouches all labeled 6 mg were measured with nearly identical total nicotine but very different free amounts:
- ZYN Cool Mint mini 6 mg - pH 8.44, about 3.71 mg free
- on! 6 mg - pH 9.58, about 5.07 mg free
- Rogue 6 mg - pH 7.96, about 2.37 mg free
That is a spread of more than 2× behind one identical number on the can. See the full mechanism in nicotine pouch pH, or run your own product through the Pouch Decoder.
Free nicotine is not the same as absorbed nicotine
Free nicotine is what is available to cross the gum. How much you actually absorb also depends on how long the pouch stays in, saliva, and pouch format - which is why the same free amount can still produce different curves. That timing question is covered in how a pouch hits.
MEASURED pH AND FREE-NICOTINE VALUES · STANFILL ET AL., NICOTINE & TOBACCO RESEARCH (2021). SLIDER USES HENDERSON–HASSELBALCH WITH pKa 8.01 AND IS ILLUSTRATIVE.
Frequently asked
- What is free nicotine and why does it matter?
- Free (unprotonated) nicotine is the form that crosses the gum quickly. How much of a pouch is free depends on pH: measured pouches range from about pH 6.9 to 10.1, a free fraction anywhere from roughly 8% to 99%. Two pouches at the same milligram can deliver very different amounts.
- How much free nicotine is in a 6 mg ZYN?
- In one lab study a ZYN pouch labeled 6 mg measured about 5.43 mg total nicotine, of which roughly 3.71 mg was free, at pH 8.44.
- Is free nicotine listed on the can?
- No. Cans list total nicotine content, or a concentration in mg/g. Free nicotine has to be measured in a lab or estimated from the product's pH.