Figure 3. Effects of temperature and humidity on λmax_Soret measurements.

To assess the effects of humidity, bloodstains were stored at 22°C (A) at various relative humidity (50% - blue diamonds, 75%-red squares, 80%-yellow asterisks, 85%-purple circles, 90%-green diamonds). For bloodstains stored at constant temperature the Soret band blue shift decreases as the humidity level increases. To assess the effects of temperature, bloodstains were stored at a constant relative humidity of 50% (C) at different temperatures (−20°C-blue diamonds, 4°C–red squares, 22°C–yellow asterisks, 30°C-purple circles, 37°C-green triangles). At constant humidity the Soret band blue shift increases with increasing temperature. For each condition, the λmax_Soret is plotted as a function of stain age (15 minutes –1 week, in hours). All data points are an average of bloodstains from two individual donors (average of triplicate measurements) and the standard error for each measurement is displayed. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article).