Phosphate Buffer (pH 5.8 to 7.4) Preparation and Recipe

A simple phosphate buffer is used ubiquitously in biological experiments, as it can be adapted to a variety of pH levels, including isotonic. This wide range is due to phosphoric acid having 3 dissociation constants, (known in chemistry as a triprotic acid) allowing for formulation of buffers near each of the pH levels of 2.15, 7.21, or 12.32. Phosphate buffer is highly water soluble and has a high buffering capacity, but will inhibit enzymatic activity and precipitates in ethanol. The buffer is one of the most popular currently used, and is commonly employed in molecular and cell biology, chemistry, and material science, among many others.

To prepare

L of Phosphate Buffer (pH 5.8 to 7.4):

Change the value in the textbox above to scale the recipe volume

Current molarity: 0.1	Adjust the molarity of the solution by using the slider below
Current pH: 7.4	Adjust the pH of the solution by using the slider below

Table 1. Required components

Component	Amount	Concentration
Sodium Phosphate Dibasic Heptahydrate (mw: 268.07 g / mol)	#	#
Sodium Phosphate Monobasic Monohydrate (mw: 137.99 g / mol)	#	#

Prepare 800 mL of distilled water in a suitable container.
Add # of Sodium Phosphate Dibasic Heptahydrate to the solution
Add # of Sodium Phosphate Monobasic Monohydrate to the solution
Adjust solution to final desired pH using HCl or NaOH
Add distilled water until the volume is 1 L.

References

This online resource may be cited as follows

MLA	"Quest Calculate™ Phosphate Buffer (pH 5.8 to 7.4) Preparation and Recipe." AAT Bioquest, Inc., 29 Oct. 2025, https://www.aatbio.com/resources/buffer-preparations-and-recipes/phosphate-buffer-ph-5-8-to-7-4.
APA	AAT Bioquest, Inc. (2025, October 29). Quest Calculate™ Phosphate Buffer (pH 5.8 to 7.4) Preparation and Recipe. AAT Bioquest. https://www.aatbio.com/resources/buffer-preparations-and-recipes/phosphate-buffer-ph-5-8-to-7-4.
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