3rd meeting of young researchers at UP 1 - IJUP - Universidade do ...

New approaches for estimating the post-mortem interval: Direct skin
surface analysis using FTIR spectroscopy
A. Queirós 1 , A. Santos 2 , A. Sousa 3 , J. Lopes 1 and A. Almeida 1
1 REQUIMTE, Department of Chemistry-Physics, Faculty of Pharmacy,
University of Porto, Portugal.
2 Service of Legal Medicine, Faculty of Medicine, University of Porto, Portugal. Forensic Sciences
Centre, National Institute of Legal Medicine, Portugal.
3 Superior Institute of Engineering, Polytechnic Institute of Porto, Portugal.
The estimation of time since death, the so called “postmortem interval” (PMI), is a main issue
in forensic sciences and one of the most challenging problems for pathologists. Most methods
currently employed have considerable inaccuracy [1].
FTIR (Fourier Transform Infrared) spectroscopy is a powerful tool for identifying types of
chemical bonds in a molecule by producing an IR spectrum that is like a molecular
“fingerprint”. In its variant “attenuated total reflectance” (ATR), FTIR spectroscopy is widely
used to study human skin. Drug absorption studies are a typical application. These studies are
generally done with in-compartment ATR accessories, and the sample must be brought in
contact with the ATR crystal within the spectrometer sample compartment. More recently,
however, in-situ skin analysis by ATR has been extended outside the box using mid-infrared
fiber optics [2]. In the last years, FTIR spectroscopy has also been applied to clinical studies
(e.g., the diagnosis of tissue pathologies). Results obtained consistently proved that the spectral
information is sufficient to distinguish between various tissue structures and also to study
disease processes at a molecular level. Very recently also, studies reporting the application of
FTIR spectroscopy to study the postmortem decomposition processes in rat lung and brain
tissues were published, and results suggested correlation with PMI [3,4].
In the scope of our Project* we are studying the utilization of FTIR spectroscopy to directly
test the human skin for possible chemical changes occurring after dead that may correlate with
PMI. Studies performed to date aimed to test the data acquisition procedure / conditions, and
particularly the best body areas for skin analysis. Postmortem studies in animal models
(chicken) showed promising results. Postmortem studies in humans are currently being
performed.
Acknowledgements: To University of Porto and Santander Totta for financial support.
*NA::EPMI2 - New Approaches for Estimating the Postmortem Interval - II: Direct skin surface
analysis using FTIR spectroscopy (Pre-Graduate Scientific Research – Pluridisciplinary Projects, 2009
Competition).
References:
[1] Henssge C, Madea B. Estimation of the time since death. Forensic Science International 2007;
165(2-3):182-4.
[2] Using mid-infrared fiber optics for in-situ studies of human skin. Molecular Spectroscopy, March
2007, p. 20.
[3] Huang P, et al. Study on estimation of postmortem interval using FTIR in rat lung. Guang Pu Xue
Yu Guang Pu Fen Xi. 2007; 27(10):1962-5.
[4] Ke Y, et al. The correlation between postmortem interval and Fourier transform infrared spectra in
rat’s brain.Guang Pu Xue Yu Guang Pu Fen Xi. 2008; 28(11):2545-9).
3 rd meeting of young researchers at UP 447