AAT Bioquest

Potassium Phosphate Buffer (1 M, pH 6.5) Preparation and Recipe

Potassium phosphate buffers, sometimes called Gomori buffers, consist of a mixture of monobasic dihydrogen phosphate and dibasic monohydrogen phosphate. These buffers have excellent buffering capacity and are highly soluble in water. However, potassium phosphate buffer reacts with some metal ions including calcium and magnesium, and inhibits enzymatic reactions. Additionally, all phosphates precipitate in ethanol, which can be deleterious to some nucleic acid preparations that typically use ethanol solutions. Potassium phosphate buffer is used in research fields ranging from molecular biology to botany, due to its adaptability and affordability.

To prepare  L of Potassium Phosphate Buffer (1 M, pH 6.5):
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Table 1. Required components
Potassium Phosphate Monobasic (mw: 136.09 g/mol)95 g0.698 M
Potassium phosphate dibasic (mw: 174.18 g/mol)52.5 g0.3014 M
  1. Prepare 800 mL of distilled water in a suitable container.
  2. Add 95 g of Potassium Phosphate Monobasic to the solution.
  3. Add 52.5 g of Potassium phosphate dibasic to the solution.
  4. Adjust the pH to 6.5.
  5. Add distilled water until the volume is 1 L.
  6. Filter sterilize and store at room temperature.

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


This online tool may be cited as follows


"Quest Calculate™ Potassium Phosphate Buffer (1 M, pH 6.5) Preparation and Recipe." AAT Bioquest, Inc.21 May2024https://www.aatbio.com/resources/buffer-preparations-and-recipes/potassium-phosphate-buffer-1-m-ph-6-5.


AAT Bioquest, Inc. (2024May 21). Quest Calculate™ Potassium Phosphate Buffer (1 M, pH 6.5) Preparation and Recipe. AAT Bioquest. https://www.aatbio.com/resources/buffer-preparations-and-recipes/potassium-phosphate-buffer-1-m-ph-6-5.