The f-potential of the particles in the samples was determined
using particle electrophoresis (Zetasizer Nano ZS series, Malvern
Instruments, Worcestershire, UK). Emulsions were diluted to a
droplet concentration of approximately 0.001 wt% using buffer
solutions of the appropriate pH and NaCl concentration to avoid
multiple scattering effects. All measurements were made on at
least two freshly prepared samples.