Phosphate buffered Saline ( PBS) is a buffer solution commonly used in biological research. It is a salty solution containing sodium chloride, sodium phosphate, and (in some formulations) potassium chloride and potassium phosphate. The buffer helps to maintain a constant pH. This SOP gives one of the most common formulations used in preparing PBS (1x PBS).
PBS can be used as a diluent in methods to dry biomolecules, as water molecules within it will be structured around the substance (protein, for example) to be ‘dried’ and immobilized to a solid surface. It is applied in washing cells after protein expression procedures due to its osmolarity and pH to avoid cell disruption to preserve and subsequently freeze the cells for downstream molecular biology applications.