What color is produced in the Evelyn-Malloy color reaction?

• A. red-purple
• B. blue
• C. green
• D. yellow

Answer: (A)

The Evelyn-Malloy reaction detects bilirubin by forming an azo dye. In this test, bilirubin reacts with a diazonium ion generated from sulfanilic acid under acidic conditions to produce azobilirubin. This dye has a red-purple hue, so the observed color is red-purple. The intensity of that color correlates with the amount of bilirubin in the sample. Other colors would come from different dye systems or reactions, not this specific azobilirubin formation.