CSI Spectroscopy – New technology for solving crimes
Researchers from the Academic Medical Center in Amsterdam have established a novel method to determine the age of bloodstains; which can be crucial in reconstructing crime events. Today, no reliable methods are available to assess the age of a blood stain on crime scenes. Bremmer et al. established a method to determine the age of a bloodstain by measuring a bloodstain’s reflectance spectrum. The results are published in PLoS One.
Hemoglobin
Upon blood exiting the body, hemoglobin, the main chromophore in blood, transits from oxy-hemoglobin into met-hemoglobin and hemichrome. Bremmer et al. developed a method to quantitatively determine blood volume fractions by non-contact reflectance spectroscopy in the VIS/NIR spectral wavelength range. The setup is portable and contains an Ocean Optics light source, probe and USB Spectrometer.
Biphasic oxidation
The transition of oxy-hemoglobin to met-hemoglobin appears to be biphasic. The biphasic nature of the transition is attributed to the different ageing rates for the alpha and beta chain of the hemoglobin molecule. At room temperature, the oxidation is fast during the first six hours and decreases thereafter. The biphasic oxidation rate follows from first order reaction kinetics and was also observed in aqueous hemoglobin solutions. Finally, the oxidation rates as a function of temperature and humidity are explored. The oxidation rate is temperature dependent, but humidity independent.
Forensic Practice
Crime Scene Investigators, local and from abroad, are very enthusiastic about the new possibilities for solving crimes. Bremmer received the prestigious Emerging Forensic Science Award from the American Academy of Forensic Sciences. Future research, in cooperation with the Netherlands Forensic Institute, will be focused on realizing the new technique into forensic practice.
Additional information:
http://www.plosone.org
Rolf Bremmer measuring the reflectance spectrum of bloodstains.
