Journal of Medical Toxicology and Clinical Forensic Medicine

The identification of chemicals to estimate the post-mortem interval of aquatic mammalian cadavers using Nuclear Magnetic Resonance and Liquid Chromatography

This study analysed water samples from controlled laboratory experiments murine models placed in ultra-pure water
and of porcine cadavers in large containers of water that were placed out in the open. Spectra and chromatograms of
targeted decomposition chemicals, specifically, free amino acids and biogenic amines were collected with a 400Mhz
JEOL Nuclear Magnetic Resonance (NMR) spectrometer using a 1H solvent suppression method and highperformance
liquid chromatography coupled to an ultraviolet detector (HPLC-UV). These techniques were used to
accurately estimate post-mortem interval (PMI) as current estimation methods may not be suitable due to the
uniqueness of each investigation. Data suggested that NMR will be useful in estimating the PMI of mammalian
cadavers discovered in an aquatic environment despite the expected low sensitivity disadvantages of the instrument
as the targeted chemicals from the samples were not extracted or concentrated considering the chemicals were
expected to be at trace levels. The chemical patterns from the NMR spectra are similar for the murine and porcine
models although at different time periods as expected most likely due to the cadaver masses, temperature conditions
and size of the containers. Although NMR can be used to quantify chemicals, poor peak resolution of the amino acids
and biogenic amines were present due to the 400MHz magnet therefore, liquid chromatography methods were
chosen to separate out and quantify the chemicals present. Three liquid chromatography methods are being
developed to separate the amino acids and biogenic amines, UHPLC-UV using a DEEMM derivatization, HPLC-FLD using
an OPA derivatization and LC-MS underivatized sample preparation, the amino acids and amines found were at
nanomole levels. Comparisons of these methods were decided by the ease and speed of sample derivatisation, limit of
detection and quantification, future portability for field use and availability of instruments to law enforcement

Author(s):

Simon Cooper

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