Effect of selected oils and co-surfactants on zeta potential.

Oil	Surfactant	Co-surfactant	Formulation code	Zeta potential
Clove oil	Tween 80	PEG-400	ClNE1	−11.67 ± 1.021
		PEG	ClNE2	−12.93 ± 1.053
		Carbitol	ClNE3	−13.21 ± 1.038
		Labrasol	ClNE4	−13.99 ± 1.213
Coconut oil	Tween 80	PEG-400	CoNE1	−13.51 ± 1.029
		PEG	CoNE2	−13.81 ± 1.091
		Carbitol	CoNE3	−14.01 ± 1.380
Olive oil	Tween 80	PEG-400	OlNE1	−12.01 ± 1.031
		PEG	OlNE2	−13.09 ± 1.078
		Carbitol	OlNE3	−15.21 ± 1.071