Youssef Farhat, Written 5/2/13, Last updated 8/1/13
The purpose of this protocol is to prepare a 20X DPBS stock solution which can then be diluted down to 1X when needed. DPBS, or Dulbecco’s Phosphate-Buffered Saline, is often used as a neutral, isotonic buffer for cell culture and in assays such as ELISAs. Be sure to sterilize DPBS if used for cell culture, or purchase a bottle of sterile DPBS from a company (such as: Gibco, #14190).
In this protocol, we will use solid NaCl (molecular weight: 58.44 g/mol), KCl (MW: 74.55 g/mol), KH2PO4 (MW: 136 g/mol), and Na2HPO4 (MW: 142 g/mol) to make 1 L of 20X DPBS stock solution.
- NaCl (VWR, #BDH0286)
- KCl (MW: 74.55 g/mol),
- KH2PO4 (MW: 136.09 g/mol)
- Na2HPO4 (MW: 141.96 g/mol)
- 12 M HCl Solution (Sigma-Aldrich, #H1758 – Note: Wear gloves, eye protection and exercise extreme caution when handling this strong acid solution. Aside from being dangerous, it also has a strong smell, so working under a fume hood is ideal.)
- NaOH pellets (J.T. Baker, #3722)
- Deionized water
- Normal lab equipment, such as pipettes, serological pipettes, graduated cylinders, beakers, a stir plate, a stir bar, a scale, pH meter
- Add the following to a 1 L beaker:
- 160 g of NaCl
- 4 g of KCl
- 4 g of KH2PO4
- 23 g of Na2HPO4
- Add 800 mL of deionized water to the beaker.
- Add a stir bar to the beaker and leave it on a stir plate until it completely dissolves (10 min)
- Check the pH with a pH meter to ensure that the solution’s pH is 7.4.
- Adjust the pH, if necessary, with HCl (exercise extreme caution!) or NaOH pellets.
- Raise the volume to 1 L with deionized water.
- Sterile-filter, if desired, and transfer to an appropriately labeled container.
Citing this Protocol