how does xanthoproteic test differ from the heller ring test?

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how does xanthoproteic test differ from the heller ring test?

2007-07-10 08:11:15 · 2 answers · asked by cHaKa dOLL 1 in Science & Mathematics ➔ Chemistry

2 answers

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2007-07-10 18:21:42 · answer #1 · answered by Doraemon 1 · 0⤊ 0⤋

In the xanthoproteic test, one mixes the sample first with con. HNO3, then with NH4OH. The first reaction is a color change to yellow, followed by further change to orange. This test depends on presence of tyrosine, which has a HO-C6H4- side chain. The phenol proup gets nitrated to nitrophenol (yellow), and the NH4OH reacts with HO- to give (-)O-C6H4-, which is orange.

The Heller ring test also uses nitric acid, but gives a white precipitated ring of denatured protein where the sample, usually urine, is carefully layered over the acid.

2007-07-10 15:34:18 · answer #2 · answered by steve_geo1 7 · 0⤊ 0⤋