Which substance is used as a filtering agent in elixirs to absorb excess oil?

• A. Bentonite
• B. Kaolin
• C. Activated charcoal
• D. Talc

Answer: (D)

In elixirs, a filtering (adsorbing) agent is added to remove and bind unwanted oily components, helping to clarify the solution without removing the desired ingredients. The substance chosen should effectively absorb oil but remain inert and not interfere with flavors or active drugs.

Talc is well suited for this role because its plate-like mineral structure provides strong oil-absorption capacity while being chemically inert in typical elixir solvents. It helps remove excess oil from the liquid, resulting in a clearer preparation without altering the active components.

Bentonite and kaolin are clays used mainly as suspending or adsorbing agents for particulates and for viscosity control, which can affect texture and flow rather than specifically targeting oil. Activated charcoal is a powerful adsorbent that can remove impurities, but it is non-selective and can strip desirable flavors or active ingredients, making it less ideal for selectively absorbing oil in an elixir.