Analyzing decomposition levels in cadaveric tissue using GC/MS

Human decomposition is associated with qualitative changes to the body, which causes some ambiguity when determining the time since death, or postmortem index (PMI). There has been a recent push in the field of forensic science to quantify decomposition with reliable scientific or analytical methods. During decomposition, bacteria perform putrefactive processes to break down the macromolecules of the body, including amino acids. Two of these amino acids, lysine and ornithine, get decarboxylated to produce diamines known as cadaverine (CAD) and putrescine (PUT). Another biogenic amine produced in a variety of reactions during decomposition is methylamine (MEA). Recent research has indicated that these amines could be quantified in liver and brain tissue to correlate their concentration to the PMI (up to one month).1,2 In the current study, these methods were applied to preserved cadaveric liver and muscle with a longer PMI (about nine months since preservation). Six weekly sets of liver and muscle tissue were collected and homogenized to extract the three amines (CAD, PUT, and MEA). Reacting the primary amines with pentafluorobenzaldehyde (PFB) formed a high molecular weight imine derivative that was detected using gas chromatography/mass spectrometry (GC/MS).3 While the initial hypothesis was that CAD, PUT, and MEA would increase along with the PMI, none of the compounds were detected in any of the liver or muscle samples. Very little research exists to show a long-term trend of CAD and PUT, which means the production of amines may plateau after early decomposition. This possibility may have caused the concentration to be under the limit of detection for the current GC/MS method. Therefore, future research will investigate the same trend in unpreserved porcine liver to see if CAD, PUT, and MEA can be detected and quantified during earlier stages of decomposition. References: 1. Balta, J. Y.; Blom, G.; Davidson, A.; Perrault, K.; Cryan, J. F.; O’Mahony, S. M.; Cassella, J. P. Developing a Quantitative Method to Assess the Decomposition of Embalmed Human Cadavers. Forensic Chem. 2020, 18 (100235). DOI: 10.1016/j.forc.2020.100235 2. Pelletti, G.; Garagnani, M.; Barone, R.; Boscolo-Berto, R.; Rossi, F.; Morotti, A.; Rof, R.; Fais, P.; Pelotti, S. 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. Forensic Sci. Int. 2019, 297, 221−227. DOI: 10.1016/j.forsciint.2019.01.025 3. Ngim, K. K.; Ebeler, S. E.; Lew, M. E.; Crosby, D. G.; Wong, J. W. Optimized Procedures for Analyzing Primary Alkylamines in Wines. J. Agric. Food Chem. 2000, 48 (8), 3311−3316. DOI: 10.1021/jf9912607