Washed red blood cells (RBCs), supplemented or non-supplemented with sodium azide, were exposed to different concentrations of hydrogen peroxide as well as ascorbic acid. Our experiments may thus imply that the non-fluorescent hemoglobin background can be modified by reactive oxygen species (ROS) and this can lead to a spurious ZPP/heme ratio.
We discuss this phenomenon with respect to ZPP quantification in clinical practice.