How to prepare Phosphate Buffered Saline (PBS)
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What is Phosphate Buffered Saline?
Phosphate buffered saline , more commonly known as PBS, is one of the most commonly used buffers in different biological research applications for maintaining the pH of a solution.
This solution consists of sodium chloride, sodium phosphate, and depending on the intended application, it can also include potassium chloride and potassium phosphate. The ion concentrations and osmolarity found in PBS more often than not match with the human body, making this solution isotonic.
PBS buffer applications
This non-toxic and isotonic buffer has a wide array of uses, including sample diluient, a rinse for cell-containing vessels. When used with additives like EDTA, PBS is well suited for disengaging clumped cells.
Preparation
For 1 litre of 10x PBS:
- Begin with 800ml of distilled water in a Duran bottle.
- Measure out and add 80.1g of NaCl.
- Add 14.4g of Na2HPO4.
- Add 2g of KCl.
- Add 2.7g of KH2PO4
- Bring the pH to 7.4 or 7.2 (depending on the application) using HCl.
- Add distilled water until the total volume reaches 1 litre.
- Sterilise in an autoclave on a liquid cycle.
- Store at room temperature.
For 1 litre of 1x PBS:
- Begin with 800ml of distilled water in a Duran bottle.
- Measure out and add 8g of NaCl.
- Add 1.44g of Na2HPO4.
- Add 0.2g of KCl.
- Add 0.24g of KH2PO4
- Bring the pH to 7.4 or 7.2 (depending on the application) using HCl.
- Add distilled water until the total volume reaches 1 litre.
- Sterilise in an autoclave on a liquid cycle.
- Store at room temperature.
Additional tips for preapring PBS buffer:
- Always try to prepare the buffer at the approximate temperature at which you will use it, as temperature fluctuations can result in a dissociation shift.
- Make sure the pH meters are correctly maintained.
- Work under aseptic conditions to eliminate the risk of contamination. Sterilise the buffer after preparation to prevent microbial buildup, which is common in phosphate-containing and neutral pH buffers like 1x PBS.
- By preparing 10x instead of 1x PBS solution, you can dilute 100ml of the 10X solution to 900ml of distilled water to obtain 1l of 1x PBS buffer.