13C6-3-Nitrophenylhydrazine hydrochloride (13C6-3-NPH) is primarily used as a derivatization agent in analytical chemistry, particularly in the analysis of carbonyl compounds such as aldehydes and ketones. It is employed to enhance the detection and quantification of these compounds in complex matrices like biological fluids, environmental samples, and food products. The labeled carbon (13C6) in the molecule allows for precise internal standardization in mass spectrometry, improving accuracy and reducing matrix effects. This chemical is especially valuable in metabolomics and environmental studies, where it helps identify and measure trace levels of carbonyl-containing metabolites or pollutants. Its application ensures reliable and sensitive analysis, making it a critical tool in research and quality control laboratories.