Used primarily as a reagent to detect and characterize aldehydes and ketones in organic analysis. It reacts with carbonyl groups to form yellow, orange, or red precipitates known as 2,4-dinitrophenylhydrazones, which are easily observable and have sharp melting points, aiding in identification. Commonly applied in qualitative testing in laboratories and in teaching environments to demonstrate carbonyl reactivity. Also utilized in some analytical methods for quantifying carbonyl compounds in mixtures, including environmental and biological samples.