>Nicotine was originally isolated from the tobacco plant in 1828 by chemists Wilhelm Heinrich Posselt and Karl Ludwig Reimann from Germany, who believed it was a poison.[210][211] Its chemical empirical formula was described by Melsens in 1843,[212] its structure was discovered by Adolf Pinner and Richard Wolffenstein in 1893

30 seconds on Wikipedia would have given you context of when the separation of nicotine occurred. Kind of hard to guess how tobacco plants make nicotine when you don't know what it is.