Dabsyl-L-alanine is a stable, colored derivative of L-alanine used primarily as an internal standard in high-performance liquid chromatography (HPLC) for the analysis of amino acids and peptides. In biochemical and analytical chemistry, it facilitates accurate quantification and identification by co-eluting with samples derivatized using dabsyl chloride, which labels primary amines to produce derivatives detectable by UV-Vis absorbance at around 436 nm. This application is crucial in research on protein composition, metabolic pathways, and clinical diagnostics, enhancing the precision of chromatographic methods without involvement in fluorescence labeling or direct use as a protective group in peptide synthesis.