Used primarily as a reagent in organic chemistry for the identification and characterization of carbonyl compounds, such as aldehydes and ketones. When mixed with a sample containing these compounds, it forms brightly colored precipitates known as 2,4-dinitrophenylhydrazones, which are useful for qualitative analysis. The solution is also employed in spectrophotometric methods to quantify carbonyl content in various substances. Additionally, it serves as a derivatizing agent in chromatography to enhance the detection of carbonyl compounds. Its applications extend to environmental testing, where it helps in detecting pollutants like formaldehyde in air and water samples.