Influence of fixation on recovery, pressure across filter and sample purity.

<p>Bars show recovery of three culture cell lines spiked into 1 mL of whole blood as a function of fixation and pore size (5 µm and 8 µm). Samples were not fixed, fixed for 4 hours in CellSave (CS) or 10 minutes in 0.4% formaldehyde (PFA). Whiskers represent 1 standard deviation. Average sample purity is defined as the % cell line of total cells and is shown below the bar plot. Peak pressure (P) is shown below the bar plot as well. Recovery and purity are both highest for no fixation. The pressure needed to pass 1 mL of blood through the filter is much larger with fixed samples, with the pressure required to pass PFA fixed blood through the 5 µm in excess of 300 mbar that could be determined on our setup.