Phosphate-buffered saline (PBS) is a buffer solution used in biological research. It is a water-based salt solution containing sodium phosphate, sodium chloride and, in some formulations, it contains potassium chloride and potassium phosphate. The osmolality and ion concentrations of the solutions match those of the human body (isotonic) and are non-toxic to most cells.

Phosphate buffered saline has been used for the production of platinum nanoparticles (NP-Pt) hydrocolloid, for the washing of blood sample and SEM stubs prior to SEM, for preparing the solution of fluorescent lectin wheat germ agglutinin (WGA), for the dilution of capture antibody during ELISA (enzyme linked immunosorbent assay), and for suspension of cell pellets during centrifugatin.

One tablet dissolved in 200 mL of deionized water yields 0.01 M phosphate buffer, 0.0027 M potassium chloride and 0.137 M sodium chloride, pH 7.4, at 25 °C.