Species distribution of a dissociating substance with two pK
values (2.5 and 9) in dependence of pH. For property estimations with EPISuite, the non-ionic fraction is of importance which was set to be at least 95% (red line) within an environmental relevant pH range of 4 to 10 (green lines). This example substance would not be included for further screening steps since the non-ionic species drops far below 95% at pH 10. The respective graph is convex within the range of interest.