HLB for oil in water emulsions

• A. 3.8 to 8
• B. 1 to 3
• C. 12 to 20
• D. 8 to 16

Answer: (D)

HLB indicates how hydrophilic or lipophilic a surfactant is, and it helps predict which type of emulsion a surfactant will stabilize. Higher HLB means more hydrophilic, which is better for stabilizing oil droplets in water (oil-in-water emulsions). In practice, a surfactant system chosen for oil-in-water emulsions usually lies in a mid-to-high HLB range, commonly about 8 to 16. This window ensures the surfactant is sufficiently hydrophilic to stabilize the interface in an aqueous continuous phase. So the best answer is the range that covers this practical O/W window. Ranges much lower favor water-in-oil systems or require lipophilic surfactants, while very high values are less typical for standard O/W emulsions.