Liquid bandage separating on agar plate?

[deleted-817768]

Hello, I'm working on a science fair project where I test the antimicrobial properties of liquid bandages. After placing 100 microliters of the liquid bandage on the agar plate it began to separate and dry strangely. Is this the liquid bandage eating away at the agar? Or could the agar be causing the liquid bandage to separate and coagulate? The main ingredients of the bandage are as follows: Benzethonium Chloride 0.2%, Amyl acetate, camphor, ethyl acetate, ethyl alcohol, n-butyl acetate, nitrocellulose.
I've attached a picture of the result. Any response is greatly appreciated.

Thank you

[norman40]

Hi froglad,

Ethyl cellulose is the liquid bandage component that forms a film on application. It is soluble in ethyl alcohol but not in water. The ethyl cellulose film forms when the alcohol evaporates after application on a surface (skin or other).

The agal gel is not soluble in ethyl alcohol so it seems unlikely that a small volume of liquid bandage solution would dissolve the agar.

It's possible that the separation you've seen is related to the formation of ethyl cellulose film on the agar surface. Or, if the agar is moist, the water may cause the ethyl cellulose to precipitate from the liquid bandage solution.

Would it be possible to test the ethyl cellulose film in your experiment? You might apply a layer of liquid bandage to a smooth surface (aluminum foil) and allow the alcohol to evaporate. The film could then be peeled away from the surface and placed in your agar plate for testing.

I hope this helps. Please post again if you have more questions.

A. Norman