I am having some troubles with PBS solution I am currently using to work with erythrocytes. When comparing the erythrocytes suspensions in PBS (pH = 7.4; 137 mM NaCl, 2.7 mM KCl, 8 mM Na2HPO4, and 2 mM KH2PO4) and in water (complete hemolysis), the PBS shows 20% hemolysis when, ideally, it should be close to 0%.
Briefly, the degree of hemolysis is determined by measuring the absorbance of the suspensions at 550 nm.
How can I assess the osmotic stability of an erythrocytes suspension?
Thanks!