nitric acid Archives - THE SCIENCE NOTES

The diagram shows three sequential test tubes illustrating the qualitative analysis of proteins containing aromatic amino acids. Step 1 shows a test tube labeled "NITRATION" where concentrated nitric acid ($HNO_3$) is added to a protein sample, beginning to form a light yellow color representing nitrated aromatic amino acids. Step 2 shows the test tube being gently heated over a small burner flame, producing a distinct yellow substance labeled "Xanthoproteic Acid" to ensure reaction completion. Step 3 shows sodium hydroxide ($NaOH$) alkali being added via a dropper, resulting in a dark yellow-orange positive result due to the intensification into an orange salt.

June 3, 2026 Biochemistry Protocols and Techniques

Xanthoproteic Test: Qualitative Protein Analysis Using Nitric Acid

Learn how the xanthoproteic test uses nitric acid to detect aromatic amino acids in proteins, including principle, procedure, results, uses, and limitations. Read more