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Phosphate buffered saline (abbreviated PBS) is a buffer solution commonly used in biological research. It is a water-based salt solution containing sodium phosphate, sodium chloride and, in some formulations, potassium chloride and potassium phosphate. The osmolarity and ion concentrations of the solutions match those of the human body (isotonic).
PBS has many uses because it is isotonic and non-toxic to cells. These uses include substance dilution and cell container rinsing. PBS with EDTA is also used to disengage attached and clumped cells. Divalent metals such as zinc, however, cannot be added as this will result in precipitation. For these types of applications, Good's buffers are recommended.
There are many different ways to prepare PBS. Some formulations do not contain potassium, while others contain calcium or magnesium.
|Salt||Concentration (mmol/L)||Concentration (g/L)|
Start with 800 mL of distilled water to dissolve all salts. Adjust the pH to 7.4 with HCl. Add distilled water to a total volume of 1 liter. The resultant 1x PBS should have a final concentration of 10 mM PO43-, 137 mM NaCl, and 2.7 mM KCl.
|reagent||MW||mass (g) 10X||[M] 10X||mass (g) 5X||[M] 5X||mass (g) 1X||[M] 1X|
|pH = 7.4|
The simplest way to prepare a PBS solution is to use PBS buffer tablets or pouches. They are formulated to give a ready-to-use PBS solution upon dissolution in a specified quantity of distilled water. They are available in the standard volumes: 100, 200, 500 and 1000 mL, and 10, 25, 50 and 100 L.
If used in cell culturing, the solution can be dispensed into aliquots and sterilized by autoclaving (20 min, 121°C, liquid cycle). Sterilization may not be necessary depending on its use. PBS can be stored at room temperature, but may warrant refrigeration to prevent bacterial growth if the solution is not sterile and is kept for long periods of time. However, concentrated stock solutions may precipitate when cooled and should be kept at room temperature until precipitate has completely dissolved before use.