An Investigation of Amino Acids in Decomposition Soil.

Decomposition chemistry is the study of the chemical processes that occur during soft tissue decomposition.  The chemistry and rate of these processes is important in the field of forensic science because of their potential to be used for the estimation of a postmortem interval (PMI). During decomposition, proteins in the body will degrade to shorter-chain compounds including amino acids, amines, and ammonium and are released into the soil surrounding a body (referred to as decomposition soil). The aim of this study was to optimize a method for the detection and quantification of amino acids in decomposition soil and to determine whether the concentrations of amino acids increase significantly during the decomposition period. Amino acids were extracted from soil using ammonium acetate, derivatised with phenylisothiocyanate, and analyzed using HPLC-UV/Vis spectroscopy.  Fourteen amino acids were identified in the decomposition soil and six of these amino acids were found to have concentrations significantly higher than the control samples. A two-peak concentration cycle was identified for all amino acids. A correlation between the amino acid cycles and decomposition period is being investigated and with further study, has the potential to provide a novel method for estimating the postmortem interval of decomposed bodies in a soil environment.