4'-Hydroxyazobenzene-2-carboxylic acid is primarily used as a matrix in MALDI-TOF mass spectrometry (MS) for the analysis of various biomolecules. Its unique properties make it suitable for enhancing the ionization efficiency of analytes, particularly peptides, proteins, and other macromolecules. The compound aids in the desorption and ionization process, allowing for accurate mass determination and structural analysis. It is especially effective in reducing background noise and improving signal resolution, making it a valuable tool in proteomics, metabolomics, and other analytical applications. Its compatibility with a wide range of samples and its ability to produce clear, reproducible spectra contribute to its utility in high-throughput and precision-based studies.