Blood stains, which are among the traces encountered most frequently at crime scenes, are important for potential extraction and amplification of DNA for suspect identification, as well for spatter pattern analysis to reveal a sequence of events. Estimating the age of blood stains with good accuracy and precision has been an elusive goal for forensic investigations. Estimates of blood stain age can contribute to verify witness' statements, limit the number of suspects and confirm alibis. Fourier transform infrared spectroscopy (FTIR) can be used in forensic detection of blood stains and age estimation because of signature absorbances in the mid-infrared region at 3300 cm-1 (Amide A), 2800 cm-1 to 3000 cm-1 (Amide B), ~1650 cm-1 (Amide I), ~1540 cm-1 (Amide II) ,and 1200 cm-1 to 1350 cm-1 (Amide III). We have observed position and intensity shifts for these peaks due to aging changes occurring as a result of the denaturation of blood proteins and water absorption/desorption with aging. Partial least square regression (PLS) and interval PLS were used in this work to combine these changes in a multivariate calibration for blood age that reveals correlations between the amide peak changes and blood age. Calibration experiments over several months at 30�C under a variety of humidity and substrate conditions enable prediction of blood stain age under different environmental conditions. This research will contribute to the understanding of mechanisms of blood aging and provide a nondestructive and simple approach for predicting blood age under a variety of environmental conditions.

Using Fourier transform infrared spectroscopy to estimate blood age under different environmental conditions

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.