If you are getting nicotine from smoking a cigarette, you know that nicotine works quickly, so it does not last long in the bloodstream. Most of the nicotine is gone in a couple of hours, which is why most people need to smoke throughout the day to keep the nicotine levels up. It would pretty much be out of your system in 24-48 hours. One thing to note is that their are some rare people who do metabolize nicotine slowly, so just be aware that it can occur.
The major breakdown product of nicotine is cotinine, which can be detected in urine. This byproduct lasts longer than nicotine, and can be found for up to one week after quiting smoking.