Which of the following are examples of nonionic surfactants?

• A. Bacterial Agents
• B. Sorbitan Esters, Polyoxyethylene Derivatives
• C. Sodium Lauryl Sulfate
• D. Egg Yolk

Answer: (B)

Nonionic surfactants are surface-active molecules that do not carry a charge in solution. They achieve their emulsifying and solubilizing action through hydrophobic tails and hydrophilic head groups that are not ionized, such as polyoxyethylene chains.

Sorbitan esters and their polyoxyethylene derivatives fit this pattern. Sorbitan esters (like Span) have a hydrophobic fatty acid tail attached to a sorbitol-derived head, and when combined with polyoxyethylene chains (as in Tween), they form nonionic surfactants with hydrophilic heads that do not ionize. This combination makes them versatile emulsifiers and solubilizers in pharmaceutical formulations.

The other options don’t fit this category. Bacterial agents are not surfactants. Sodium lauryl sulfate is an example of an ionic surfactant (anionic) because its sulfate group dissociates in solution to carry a negative charge. Egg yolk contains phospholipids that can act as natural emulsifiers in foods or biological contexts, but it is not classified as a nonionic surfactant used in pharmaceutical formulation.