I had a problem with a test for a sample. The sample consists of glucose, vitamin C and proteins.
But when I use Biuret test to test for the presence of proteins. After adding Cu(II)SO4 into the sample.
It turns cloudy and the colour turns yellow. Are there any errors in my experiment? Why the sample doesn't
turn blue finally? I had already followed the instructions. After adding NaOH, then add some drops of Cu(II)SO4.
I had done all of this, but why can't I get the correct result?