Nicotine and cotinine levels in blood and urine from forensic autopsy cases

We measured nicotine and cotinine levels in blood and urine from 31 forensic autopsy cases. Initially, we developed a sensitive and reproducible gas chromatographic method with a minimum limit of detection of 2.1 ng/ml for both nicotine and cotinine. Calibration curves for nicotine and cotinine were linear in the ranges of 2.1-1030 ng/ml (r2=0.994-0.999) and 2.1-1380 ng/ml (r2=0.998-0.999) respectively. Our population included 13 smokers and eight of these smokers committed suicide. They showed high levels of nicotine and cotinine at 65.1-205 ng/ml (mean: 115 ng/ml) and 31.3-938 ng/ml (mean: 405 ng/ml) in blood, respectively, and 234-7290 ng/ml (mean: 1940 ng/ml) and 143-4620 ng/ml (mean: 1170 ng/ml) in urine, respectively. None of these individuals consumed nicotine preparations or tobacco leaves. In five smokers who did not commit suicide, nicotine and cotinine levels were 4.4-62.1 ng/ml (mean: 33.2 ng/ml) and 49.9-217 ng/ml (mean: 140 ng/ml) in blood, respectively, and 158-314 ng/ml (mean: 246 ng/ml) and 68.9-300 ng/ml (mean: 179 ng/ml) in urine, respectively. Our results suggest that there may be a marked increase in consumption of cigarettes in smokers with suicidal thoughts.