In e-cigarette liquids, instead of using tobacco leaves, people use liquid nicotine solution, a product usually obtained from tobacco leaves.
Nicotine, 3-[1-methylpyrrolidin-2-yl]pyridine, contains what chemists call chiral carbon. This molecule usually has two non-superimposable structures, called enantiomers. They have the same chemical formula, but the positions of their atoms may be different, making the two molecules non-superimposable, such as left and right hands; mirror images or enantiomers of each other. In chemistry, these two enantiomers are S- and R-nicotine.
Since S-nicotine rotates plane polarized light to the left (levorotatory) and R-nicotine to the right (dextrorotatory), S- and R-nicotine can be distinguished optically. A recent basic concept in stereochemistry, a mixture in which the two enantiomers coexist in a 1:1 ratio is called racemic (the deviation of plane polarized light is zero). In the case of nicotine, the racemic mixture is called RS-nicotine.
In fresh tobacco, the alkaloid array is typically composed of 93% S-nicotine1, 3.9% S-anatabine2, 2.4% S-nornicotine3, and 0.5% S-anabamine4.
Extraction of alkaloids is achieved by organic solvents and distillation of crushed crops. Nicotine and alkaloids are soluble in solvents such as alcohol, chloroform, ether, petroleum ether, kerosene, and water. The use of microwave heating and solvent mixing can increase the nicotine extraction rate, shorten the extraction time, and ensure that the product purity reaches 99.9% pharmaceutical grade.
Another method is to use salt treatment and convert the liquid into sulfate. This method requires bleaching agents to remove impurities. The sulfate is then reduced to a usable form with reagents. The bleached liquid seems clearer and is mistakenly believed to be purer.