Can nicotine be tested in your blood after 24 hours of not smoking?

Nicotine: To determine whether someone uses tobacco or has been exposed to secondhand smoke. One cans measure the level of nicotine as "cotinine" in blood, urine, saliva, or sometimes hair.

Yes: “When someone stops using tobacco and nicotine products, it can take more than two weeks for the blood level of cotinine to drop to the level that a non-tobacco user would have and several weeks more for the urine level to decrease to a very low concentration.” REF: http://labtestsonline.org/understanding/analytes/nicotine/tab/test/