Influence of relative humidity and temperature on human whole blood drying

Abstract

The drying of human whole blood pools has been studied experimentally to improve the understanding of drops and pools of human whole blood. Here blood is assimilated to a complex fluid made of several bio-colloids. The blood pools were created inside a glove box under controlled conditions. We performed experiments at temperatures of 21 °C, 29 °C, and 37 °C, and relative humidity ranging from 20 % to 70 %. The air inside the glove box was still, and the evaporation process was mainly purely diffusive. A human blood diffusion coefficient of (1.08 ± 0.02) × 10 −9 m 2 /s was obtained. This value is in agreement with literature values for polymers and colloidal films. Moreover, we elaborated an updated model using Page's model to describe the drying kinetics of human blood pools. The effect of the surface area of pools was considered using a diffusive characteristics time. These findings are of interest for biomedical and forensic applications.

Elemental and molecular characterization of degrading blood pools

“…10 Whole blood is a colloidal suspension composed of solid cellular components (∼45% by volume) suspended in liquid (∼55% by volume). 10,11 The liquid component is plasma which contains 92% water with several dissolved components including mineral salts and ions (e.g. NaCl), soluble gases (e.g.…”

“…Of the cellular components, RBCs are the most abundant, with hematocrit varying between 38-50% in healthy individuals. 11,12 As dried bloodstains are typically comprised of ∼97% hemoglobin, the primary component of red blood RBCs, 8 it is often the primary biomarker chosen to study and estimate TSD. Hb consists of four subunits with each containing one polypeptide chain and a heme group.…”

“…In works that have analyzed blood pools, characterization and TSD modelling has focused on the physical morphology and drying dynamics of the blood. 10,11,[14][15][16] Observing and quantifying the blood pool's mass, volume, colour, moisture ratio, area, and surface morphology, the drying dynamics of bloodstains has been divided into five distinct stages. 11 When the whole blood is deposited on a surface, all cellular components are evenly distributed through the pool.…”

“…10,11,[14][15][16] Observing and quantifying the blood pool's mass, volume, colour, moisture ratio, area, and surface morphology, the drying dynamics of bloodstains has been divided into five distinct stages. 11 When the whole blood is deposited on a surface, all cellular components are evenly distributed through the pool. Within minutes the RBCs sediment and evaporation take place, and a gel transition visibly occurs before complete desiccation.…”