AF 430 carboxylic acid is a derivative of the yellow fluorescent dye AF 430. The excitation wavelength of AF 430 is 425 nm, and its emission wavelength is 542 nm. AF 430 carboxylic acid can form covalent bonds through a condensation reaction between its carboxylic acid group and molecules containing amino groups, facilitating dye labeling and specific conjugation with biomolecules.