Nicotine is toxic, and it is extractable into water.
That's it. That's all you need to know. The specifics aren't necessary. You're a script writer. With good cinematography, acting, film work and scene direction, you can generate verisimilitude -- a subtle falseness that makes people want to believe even more. This happens in all movies and plays - people shut off their brains for a little while and just accept everything. They may rapidly snap out of it, eventually snap out of it, or in rare cases, never snap out of it depending on how hard they think about it. Some people never fall in, we call those people critics.
Extra science facts will not help you. If you put too many in it will be boring. A little research to support your plan, and fact fudged here and there is fine for a script.
Often a person will ask on these boards to find out the best, easiest, fastest, weirdest, most unique or least traceable way to kill, injure, daze, or mind control someone ... for literary purposes only. And there's no printed rule on this page against that. But really, do you think there should be comment after comment, fine tuning a criminal act ... even theoretically?