Determination and Correlation of Electrolytes and Trace Elements from Vitreous Humour and Synovial Fluid by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for Estimation of Post-Mortem Interval (PMI): Experimental Study in an Animal Model

Abstract

The estimation of post-mortem interval (PMI) procedures seem to subjectivity in assessment and less
sensitivity and specificity. Biochemical determination of trace elements from closed-system samples,
such as vitreous humour (VH) and synovial fluid (SF) is an alternative laboratory investigation for PMI
estimation. The inductively coupled plasma-mass spectrometry (ICP-MS) provides more rapid, precise and
sensitive analysis of elements samples. However, determination of electrolytes and trace elements in VH
and SF by ICP-MS, and application for PMI has not been intensively investigated. In this study, VH and
SF from twenty adult domesticated pig carcasses were collected at 1, 3, 6, 12, 24, 36, and 48-hour after
death. Samples were analysed for total protein concentration, Ca, Cu, Fe, K and, Na using ICP-MS. The
results showed that the protein concentration in VH was significantly increased in time dependent manner,
but not for SF. The level of K and Fe in both VH and SF increased in time dependent manner, with a good
correlation between both sample sources. The calcium concentration of both VH and SF increased in time
dependent manner, but there was no correlation between both sample sources. Sodium was significantly
reduced at 36-48 h, with a correlation between both sample sources. However, the copper level in VH was
increased at 36-48 h but reduced in SF. In conclusion, this study showed for the first time that multiple trace
elements and electrolytes could be detected, using the ICP-MS, in both of VH and SF simultaneously and
additionally its correlation.