IJUP08 - Universidade do Porto

New approaches for estimating the postmortem interval based on
vitreous humor trace element levels
H. Andrade 1 , A. Almeida 1 , S. Frazão 2 , T. Magalhães 2 and A. Santos 2
1 REQUIMTE, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, Portugal.
2 Serviço de Medicina Legal, Faculdade de Medicina, Universidade do Porto, Portugal. Serviço de
Patologia Forense, Instituto Nacional de Medicina Legal, I.P. – Delegação do Norte.
The estimation of the postmortem interval (PMI), i.e., the time since death, is a main issue
in the field of forensic science and legal medicine [1]. Most of the currently employed
methods use body temperature-based algorithms, which are subject to considerable
inaccuracy [2].
In the last 60 years, numerous methods for estimating PMI based on concentrations
changes in body fluids have also been proposed. The postmortem increase of potassium in
vitreous humor (VH) has been the most studied, and several formulae have been proposed
for estimating PMI based on it [3]. However, the correlation between K concentration in
VH and PMI depends on several factors (e.g., cause of death, previous electrolyte
imbalance, etc.), which influences the accuracy of PMI estimation.
Recently, studies with animal models (rabbits) have shown that changes of several trace
element levels in VH could correlated with PMI within different intervals after dead and
could represent a reliable alternative strategy for estimating PMI [4-5].
The work we have been done is intended to address this topic: to look for more accurate
methods for the determination of PMI based on VH trace element levels. Using an
analytical methodology based on Inductively Coupled Plasma-Mass Spectrometry (ICP-
MS) technique, samples of VH collected from human bodies at different times since death
(3-30 h) were analyzed. From the tested elements (Ag, Al, As, Sb, Cr, Ba, Be, Co, Cu, Cs,
Cd, Mo, Mn, Ni, Li, Fe, Sr, Pb, Rb, Tl, V, Zn, Si, I and Ti), some showed promising for the
intended purpose, specially Rb, which showed a consistent non-linear increase in all the
cases studied (n=8).
References:
[1] Henssge, C. and Madea, B. (2007), Estimation of the time since death, Forensic Science
International, 165(2-3), 182-184.
[2] McDowall, K.L., Lenihan, D.V., Busuttil, A., Glasby, M.A. (1998), The use of absolute refractory
period in the estimation of early postmortem interval, Forensic Science International, 91(3), 163-170.
[3] Madea, B. (2005), Is there recent progress in the estimation of the postmortem interval by means of
thanatochemistry?, Forensic Science International, 151(2-3), 139-149.
[4] Xu, X.M., Gong, Z.Q. and Sun, Y.G. (2002), Study on the relationship between PMI and the
concentration of magnesium and iron in the vitreous humor of rabbit after death, Fa Yi Xue Za Zhi,
18(2), 65-66.
[5] Gong, Z.Q., Xu, X.M., Zeng, X.B., Sun, Y.G. and Wang, D.W. (2001), Study on the relationship
between PMI and the concentration of zincum and nickel in the vitreous humor of rabbit after death, Fa
Yi Xue Za Zhi, 17(3):129-131.
[6] Gong, Z.Q., Zeng, X.B. and Sun, Y.G. (2002), Study on the relationship between PMI and the
concentration of 21 elements in vitreous humor of rabbit after death, Fa Yi Xue Za Zhi, 18(2):67-69.
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