biuret reagent

[lab-woman]

Hi Everyone,

I just made a fresh batch of buiret reagent using 1.5g cop sulfate, 6g potassium iodide, 500ml dist water and 300ml of 10% NaOH.

It was blueish in colour and worked well (our egg whites went purple). But now Im about to put into dropper bottles etc and its already gone brown.

Did I do something wrong??

Can I recover it ?

Thanks

[sunray18]

??? Well this is a new lone for me.. to do biuret test we just use drops of 0.25M copper sulfate and then 1M NAOH .. is the test different to the reagent?

[lab-woman]

Thanks sunray. This way worked perfect. I did get my above recipe out of the "Working in Science" book. But i will stick to your way. Much easier.