[Super Newb]

Hi all!

I am looking at an assay to detect for the p-aminophenol impurities present in paracetamol. It involves the addition of sodium nitroprusside (in alkaline solution) to form a blue color solution. I would like to know what could be the blue derivative. More information on the assay can be found here: http://books.google.com.sg/books?id=s_sBKJNf184C&pg=PA1076&lpg=PA1076&dq=p-aminophenol+nitroprusside&source=bl&ots=zUONjyusTX&sig=3hQJCJGyh2FEVnV_p7cgEk28pVk&hl=en&sa=X&ei=jbSGUILCHpHMrQfv7oGwBw&ved=0CCYQ6AEwAQ#v=onepage&q=p-aminophenol%20nitroprusside&f=false

Any help will be greatly appreciated :DD

[Arkcon]

Sodium nitroprusside gives a blue color for some secondary amines:  http://en.wikipedia.org/wiki/Sodium_nitroprusside#Use_in_forensic_science  If you use its IUPAC name:  sodium pentacyanonitrosylferrate(II), you'll see it has a cyanoferrate group, that can change color from red to blue when certain complexes form. http://en.wikipedia.org/wiki/Simon%27s_reagent

[Super Newb]

However,the mixture does not contain acetyldehye to facilitate the formation of enamine intermediate

[xxsamxx]

HI!! I am also thinking about this question. Am wondering if you have figured it out??? Please do reply asap!!! thank you!!!

I would think a transition metal compound has formed?