Aside from the obvious answer of “quit smoking immediately” and maintaining adequate hydration, there is not much more you can do. Nicotine has a halflife of 60-120 minutes when inhaled and it is metabolized in the liver. There are tests the directly test for nicotine in which case it would be undetectable if you quit within 14 days. However, there are other tests that screen for the metabolites of nicotine – many of which we do not have an accurate answer for how long they remain in the body. Therefore, the best advice for your health is to quit and remain nicotine free as soon as possible.