Mass Spectrometry

Biography

Biography: Guang-Hui Zhu

Abstract

Time of death (TOD) is usually estimated based on corpse phenomenon in the early postmortem stage, and on the development of necrophagous flies in the late postmortem stage. However, after the adult emergence, the latter is not useful any more. Our previous studies found that composition of puparial hydrocarbon had significantly regular time-dependent changes during the weathering in the field in Chrysomya megacephala and C. rufifacies,   indicating that puparial hydrocarbons have a great potential for determining the TOD in the late decomposition stage of corpses. Here SIM mode of GC-MS was used to quailitify the time-dependent changes of puparial hydrocarbons  in the field  in Boettcherisca peregrina in the Autumn, 2013. We found that nearly all of the hydrocarbons decreased in the abundance during the 90-d weathering. Most of the peaks shared similar weathering profile. Their abundance decreased significantly during the first 10 days, changed hardly during the next 10 days or so, and decreased  rapidly in the next 20 to 30 days, then changed very few. Even so, during the last 10 days, some significant changes still can be detected. Generally, most of the hydrocarbons weathered linearly during the first 40 days, and the weathering rate was found to correlate with hydrocarbon classes and ECL. Additionally, the specific weathering profile of the hydrocarbons is considered to correlate with the corresponding relative low temperature weather process during the weathering. Together with those in other two species flies, these results show that puparial hydrocarbons have a great value for determining the TOD.