Xanthoproteic's Test - Colour Reaction of Proteins


Xanthoprotein is a yellow acid substance formed by the action of hot nitric acid on albuminous or protein matter and is changed to a deep orange-yellow colour by the addition of ammonia. The colour reaction is used to identify such proteins in the Xanthoproteic Test.


This video lesson demonstrates the laboratory procedure in Xanthoproteic Test. At the end of the lesson, students should be able to write a well-balanced reaction equation, distinguish between amino-acids with a phenyl ring, a phenol or an indole group from other amino acids and describe the test and positive result.

Author(s): George KoffuorView Details of Author
Year: 2012
Keywords: xanthoproteic test, amino acids, phenyl ring, phenol, indole group, amino acids, qualitative test
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Xanthoproteic Test is used to distinguish amino acids with a phenyl ring, a phenol or an indole group from other amino acids.

This reaction is due to the nitration of phenyl rings present in Tyrosine, Phenylaline and trytophan (amino acids) to give Xanthoprotein yellow substituted products. On addition of alkaline to these, a salt changes the colour from yellow to orange.



Write a well-balanced equation reaction for Xanthoprotiec test

Distinguish between amino-acids with a phenyl ring, a phenol or an indole group from other amino acids

Describe the test and positive result.


Lesson Content


Xanthoproteic's Test (video)
Xanthoproteic's Test






Dr. George Koffuor
Department of Pharmacology
College of Health Sciences - KNUST
Kumasi, Ghana

Student Volunteer

Manasseh Amenyedokui
Department of Communication Design
Kumasi, Ghana


OER Technical Support




Benjamin Prempeh
OER Media Specialist
KNUST, Kumasi - Ghana

John Kofi Dogbey
Media Specialist
KNUST,Kumasi - Ghana

Voice Over

ella kasanga

Ella Kasanga
Kumasi, Ghana




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