There appears to be relatively little data concerning forensic doses in the human organs, but it is valuable for the determination of death from drug poisoning in the forensic field. Therefore, we constructed a validated assay for nicotine and cotinine that is applicable for solid tissue samples extracted from eight human organs. Generally, analyses using only solid samples are recognized as more complicated than those using blood or urine samples as researchers require a useful extraction method for dealing with the protein and lipid content. It is also indispensable to choose assays in which full validation can be carried out without blank matrices. Therefore, we selected a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction method and surrogate analyte approach for our LC-MS/MS assay, and applied them to a case of acute nicotine poisoning. We accomplished all of our assay with good linearity (R² values>0.996), and the forensic doses of nicotine were calculated to be 1.91μg/mL in the liver, 1.87μg/mL in the iliopsoas muscle, 1.99μg/mL in the heart, 1.34μg/mL in the spleen, 3.05μg/mL in the lung, 2.26μg/mL in the kidney, 2.46μg/mL in the pancreas and 2.46μg/mL in the brain. To improve the quickness, effectiveness and ease-of-use of the extraction method, all steps in the sample preparation in our method were made as simple as possible. We believe that this method can be applied to various analyses in the forensic field irrespective of the target samples.