Freebase is the purest form of nicotine, and is the most commonly used form of nicotine in e-liquid. Freebase nicotine is created by adding ammonia to pure nicotine. This must be done because nicotine by itself would not be very potent in the body at all; nicotine is made up of negatively charged particles which essentially means that, when it enters the body, the particles cannot move across organic membranes very well. 

So, we must ‘freebase’ the nicotine in order to make it more effective in the body and increase the bioavailability. (Bioavailability refers to the amount at which a substance is absorbed by the body). The vast majority of e-liquids on the market contain freebase nicotine.

The alternative form of nicotine used in e-liquids is nic salts. These are found naturally in the tobacco leaf, meaning you will have already experienced them if you have smoked a traditional cigarette! Nic salts can cause a softer, smoother throat hit even at high doses.