Science Buddies: "Ask an Expert"

hi,
I am doing a variation on a crime scene chemistry project. I want to know if iron nitrate (ferric nitrate) will detect ground up aspirin if it is mixed with milk? What would the procedure be? If iron nitrate doesn't work, is there another method that would detect the presence of ground aspirin mixed with milk and also the aspirin residue left on the inside of the milk container.
Thanks,
Ali

Hello silvafam04,

The iron nitrate test for detecting aspirin in water is described at the following link:

https://www.sciencebuddies.org/science- ... #procedure

In this test, NaOH is added to the solution to break the aspirin into two components, acetic acid and salicylic acid. Next, iron nitrate is added to the solution. The iron combines with salicylic acid to form a purple complex.

Some components in milk might interfere with the reactions involved. But you can find out if the iron nitrate test works by testing milk without any aspirin in it, and again with aspirin in it. My suggestion is to follow the procedure described in the link above. If you do not get a blue/purple color in milk alone and you do get a blue/purple color with aspirin dissolved in milk then the test works.

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

A. Norman