Validation and preliminary application of a GC-MS method for the determination of putrescine and cadaverine in the human brain: a promising technique for PMI estimation.

Among the several techniques proposed for the estimation of the Post Mortem Interval (PMI), the analysis of odorous amines has been applied in the past, with conflicting results. The aims of this study are: (i) to develop and validate a GC-MS method for the determination of putrescine (PUT) and cadaverine (CAD) in the human brain (validation study) and (ii) to study the relation of PUT and CAD concentration in the human brain and the PMI (decomposition study). Validation study. Analysis has been performed through GC-MS after a liquid-liquid extraction and a single step-derivatization for the identification and quantification of odorous amines in brain cortex samples. The standard protocol used in forensic toxicology, slightly modified for endogenous compounds according to recent guidelines, was used for validation. Decomposition study. Three uninjured human brains were sampled during the autopsy of three fatal traumatic cases. Along a 120-hour period of decomposition under experimental conditions, each brain was sampled along predetermined time intervals. Validation study. Both PUT and CAD validation parameters were within the acceptable values defined by the Scientific Working Group for Forensic Toxicology (SWGTOX), with better selectivity, linearity, accuracy and precision values for PUT. Decomposition study. A significant relationship between PUT and CAD levels and PMI has been demonstrated through statistical analysis with a correlation coefficient of 0.98 for PUT and 0.93 for CAD (p < 0.0001). Although further experimental studies on a wider number of samples are necessary, the results of this study suggest a possible role of polyamine levels in brain cortex for the estimation of PMI.