Post Mortem Interval (PMI) Indicators
Citrate is present in the human body with about 90% of it found in living bone at a constant, well defined concentration (1.5 to 2.0% wt%). After death it disappears from the bone at a well defined rate. That progression does not appear to be strongly dependant on storage conditions except that citrate is not lost at temperatures below 0oC.
Variations in citrate content of bone is not age or sex dependant especially in cortical bone, however, immature, poorly mineralised bone might contain less citrate, as may osteoporotic bone.
Pig bone contains the same concentration of citrate as human bone (averaging 1.96 ± 0.06 wt%) and is therefore suitable for experimental purposes.
A study showed that buried pig bone did not show a significant drop in citrate in the first 30 days (1.974 to 1.945 wt%) but by 180 days the level had dropped to 1.470 wt%. It was suggested that calculations concerning the decrease of concentration over time could be accurate to about 1,000 days PMI.
Reference source: Schwarcz et al 2010
© Hadyn R Green 2012
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