How long Nicotine lasts in the blood?

i am going in for a clinical trial that says that i cant have smoked for 2 weeks. i have not smoked for around two months. yet over the weekend smoke a couple of cigar's. how long will it take for the nicotine in my blood to be gone? also, i found this website while trying to research an answer an would like to know if it holds any ground, http://www.fbr.org/publications/pamphlets/cotinine.html