Figure 2 shows the zeta potential versus pH plots for a series of lipid emulsion samples of different formulation. These measurements were performed on a Zetasizer 3000 HSA in conjunction with the MPT-1. The plots show how the stability of each emulsion formulation is affected by changes in pH.
The shaded area in the diagram (between +30mV and -30mV) shows the region in which the sample should be least stable.