Forensic electrochemistry: time since deposition (TSD) estimation of degrading bloodstains using differential pulse voltammetry

Abstract

Methods for bloodstain time since deposition (TSD) estimation are still in development. Hemoglobin (Hb) oxidative changes remain one of the primary means of bloodstain aging. This research explores the use of differential pulse voltammetry as a technique to analyze degrading bloodstains. The optimized conditions were determined to be 1μL of whole blood analyzed in a pH 7.0 phosphate buffer. This protocol was used to measure changes in electrochemical response in a two-week time series experiment using 9 biological replicates across 5 environmental conditions. Linear mixed models suggested that the peak height and area ratios for the Hb redox reactions were significantly correlated with time (p < 0.033). Absolute dating and principal component analysis demonstrate significant changes (p < 0.043) at the 96-hour time point and present opportunities for forensic TSD predictions. Overall, the changes in Hb redox peaks over time offers insight into oxidative changes and cellular degradation in bloodstains.