m-Tolualdehyde 2,4-dinitrophenylhydrazone is a specific hydrazone derivative used primarily as an analytical standard in chromatography for the identification and quantification of m-tolualdehyde (3-methylbenzaldehyde) in complex samples, such as environmental, food, or industrial matrices. It is typically employed in HPLC-UV methods after derivatization of carbonyl compounds with 2,4-dinitrophenylhydrazine (DNPH). This standard enables accurate calibration, peak identification, and measurement of aldehyde concentrations due to its characteristic UV absorbance. Its high purity and stability make it essential in quality control, regulatory compliance testing, and research on volatile organic compounds.