Phosphate buffer solution containing trypsin, used to maintain a stable pH (approximately 6.8) in biological and chemical experiments. The inclusion of trypsin (conforming to 2020 CP, 8004 general rules) makes it ideal for cell dissociation and trypsinization in cell culture, as well as protein purification and enzyme reactions where pH control is critical. Commonly applied in diluting substances for immunoassays, washing steps in ELISA and Western blotting, and pharmaceutical formulations to ensure drug stability. Also employed in diagnostic kits, sample preparation for HPLC and other analytical techniques. Suitable for ophthalmic and injectable preparations due to its biocompatibility, and particularly useful in medical research for handling biological samples like blood or tissues.