Alcohol is lost from the blood to the tissues in propoion to the water content of the tissue with which it comes in contact, till equilibrium is reached between blood and tissue. Relative concentration of alcohol at equilibrium in different samples is given below: Sample Relative concentration Whole blood 1.00 Plasma 1.12 - 1.2 Brain 0.85 Spinal fluid 1.1 - 1.27 Urine 1.3 Liver 0.85 Ref: Textbook of Forensic Medicine and Toxicology by Narayan Reddy, Edition 21, Page - 491