Which reagent is used in the Zimmerman test for 17-ketosteroids?

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

Answer: (C)

The Zimmermann test detects 17-ketosteroids by a specific color reaction with a dinitrobenzaldehyde derivative under alkaline conditions. The 17-ketosteroid possesses an enolizable ketone at C-17, which reacts with 3,5-dinitrobenzaldehyde to form a colored condensation product, typically a red color. This chromogenic reaction makes it a rapid qualitative test for ketosteroids in urine.

Among the options, the reagent that fits this chemistry is the dinitrobenzaldehyde derivative. It is this reagent that produces the characteristic color change used to indicate the presence of 17-ketosteroids. The other substances do not give that same Zimmermann color reaction: hydroxyquinone does not form the diagnostic red adduct in this test, DNPH is used for general carbonyl detection via hydrazone formation (not the Zimmermann mechanism), and formaldehyde is not involved in this specific ketosteroid screen.