A new marker for estimation of bloodstain age by high performance liquid chromatography

Abstract

The applicability of a new marker for estimation of bloodstain age by reverse-phase high performance liquid chromatography (HPLC) is described. Using a μBondasphere C18 column with a two step linear gradient of 10.5–46.25% acetonitrile in 0.1% trifluoroacetic acid, an intriguing peak (unidentified) at a retention time of about 5 min was observed on chromatograms from human adult bloodstains and designated as ‘X’. The area of this peak, which could be detected in extracts of bloodstains, but not in their fresh whole blood, increased with time. The ratios of the X area to heme area in bloodstains stored at room temperature and 4°C for up to 52 weeks old linearly correlated with stain age by plotting on a double logarithmic scale. In bloodstains exposed to fluorescent light at room temperature, the regression equation calculated from the ratios ( R x) and the ages of stains in weeks (W) is ln(1000 · R x) = 1.1084 + 0.3937 · ln(7 · W), and the coefficient of correlation ( r) is 0.9776 ( n = 144, P < 0.001). When stains were stored at 37°C, the ratio transformed into logarithms correlated linearly with stain age. The regression equation describing the relationship in bloodstains exposed to fluorescent light at 37°C is ln(1000 · R x) = 2.4477 + 0.0866 · W ( r = 0.9826, n = 144, P < 0.001). The results of the present study suggest that the HPLC method may be applicable to the estimation of bloodstain age.