In the Kober test for urinary estrogen, which reagent yields a pink color with sulfuric acid?

• A. Hydroxyquinone
• B. Hydroxycorticosteroid
• C. DNPH
• D. Dinitrobenzene

Answer: (A)

In this test, the key idea is that a specific reagent reacts with urinary estrogen under strongly acidic conditions to produce a pink color. The reagent used in the Kober test is hydroxyquinone. When estrogen is present, it reacts with hydroxyquinone in sulfuric acid to form a pink chromophore, giving a visible pink result. The other reagents don’t produce this pink color in the same acidic estrogen reaction: DNPH targets carbonyl compounds and gives a different color, dinitrobenzene isn’t the reagent for this estrogen test, and hydroxycorticosteroid would not yield the pink chromophore in this setup. So, hydroxyquinone is the reagent that yields the pink color in the Kober test.