AAT Bioquest

Citrate-Phosphate Buffer (40 mM, pH 5.6) Preparation and Recipe

A traditional buffer originally introduced in 1921. Since the Citrate-Phosphate buffer (also known as the McIlvaine buffer) only has 2 ingredients, the recipe can be adjusted to a pH range of 3-8. It is used for multiple applications in cell biology, molecular biology, and hematology.

To prepare  L of Citrate-Phosphate Buffer (40 mM, pH 5.6):
Change the value in the textbox above to scale the recipe volume

Table 1. Required components
Sodium phosphate dibasic (anhydrous) (mw: 141.96 g/mol)2.82 g0.01986 M
Citric Acid (mw: 192.12 g/mol)4.2 g0.02186 M
  1. Prepare 800 mL of distilled water in a suitable container.
  2. Add 2.82 g of Sodium phosphate dibasic (anhydrous) to the solution.
  3. Add 4.2 g of Citric Acid to the solution.
  4. Add distilled water until the volume is 1 L.
  5. Sterilize by autoclaving. (The final solution contains 20 mM Na2HPO4.)

Physiological Buffer
pH Buffering
Sample Preparation
Cell/Culture/Growth Media
Gel Electrophoresis


This online tool may be cited as follows


"Quest Calculate™ Citrate-Phosphate Buffer (40 mM, pH 5.6) Preparation and Recipe." AAT Bioquest, Inc.23 Jul2024https://www.aatbio.com/resources/buffer-preparations-and-recipes/citrate-phosphate-buffer-40-mm-ph-5-6.


AAT Bioquest, Inc. (2024July 23). Quest Calculate™ Citrate-Phosphate Buffer (40 mM, pH 5.6) Preparation and Recipe. AAT Bioquest. https://www.aatbio.com/resources/buffer-preparations-and-recipes/citrate-phosphate-buffer-40-mm-ph-5-6.