Vapouround magazine VAPOUROUND MAGAZINE OCTOBER ISSUE19 - Page 34

VAPE SCIENCE The Science Bit By Richard Cunningham, Ph.D The hot topic of the global industry this year has been salt-based nicotine, with more and more e-liquid brands launching ‘nic salts’ of their own in recent months. Look it up online and the generic websites give inaccurate reports of what salt-based nicotine really is, where it comes from and what it can potentially achieve. There are even brands out there with inaccuracies on their packaging. So, let’s go back to basics in this in-depth look at salt-based nicotine and see what all of the fuss is about. The chemistry As we’re all aware, nicotine is found naturally within the leaves of the tobacco plant, which is in the Solanaceae plant family. Also members of that family are the tomato, potato and pepper and these actually contain very small quantities of nicotine. In its naturally occurring form within the leaves of the tobacco plant, nicotine is found as a salt. To try to put it simply, these ‘salts’ are compounds that consist of a positively charged cation (+) of a base and a negatively charged anion (-) of an acid, which through electronic interactions, coordinate together to form a neutral salt complex. The molecule of nicotine is basic, which without delving into too much chemistry means that it can accept H + ions, also known as protons. Whereas, an acid is a H + donor which means it can donate protons. If nicotine was reacted with an acid such as hydrochloric acid (HCl), we would form nicotine hydrochloride which is a salt, this can be seen in the chemical equations shown. When a nicotine molecule accepts a proton from hydrochloric acid, it becomes overall positively charged (protonated) and forms a ‘salt’ with the negatively charged chloride anion from the acid to give a complex with a neutral net charge. N N 34 | VM19 CH 3 Nicotine In order to isolate nicotine from the tobacco leaf, one method is to react it with a strong base such as ammonia (NH 3 ). This converts the nicotine salt to its freebase by removing a proton. Using the example of nicotine hydrochloride again it can be explained in the below equation. NH 3 + Nicotine hydrochloride = NH 4 Cl (ammonium chloride) + nicotine ‘freebase’ This ‘freebased’ nicotine can then be extracted and isolated from the crude using solvent extraction and subsequently purified. It is purified nicotine freebase isolated from the tobacco plant that is used in the majority of e-liquids. Nicotine can also be made synthetically, however, this is significantly more expensive, although as production methods become more efficient, the cost of producing synthetic nicotine is decreasing. - C1 + N + 1 HC1 (one equivalent) N CH 3 C 10 H 15 N 2 C1 H