HEPES Buffer Recipe

1 M HEPES-KOH pH 7.5

To prepare a 1 M HEPES stock solution with potassium hydroxide, mix the following reagents:

• 700 ml ultrapure water
• 238.30 g HEPES
• potassium hydroxide pellets to adjust pH to 7.5

Bring the final volume to 1 liter with ultrapure water. Sterilize by filtration.

1 M HEPES-NaOH pH 7.5

To prepare a 1 M HEPES stock solution with sodium hydroxide, mix the following reagents:

• 700 ml ultrapure water
• 238.30 g HEPES
• ~5.5 g sodium hydroxide pellets to adjust pH to 7.5

Bring the final volume to 1 liter with ultrapure water. Sterilize by filtration.

Note: HEPES — synonyms: 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid; N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid). Empirical formula (Hill notation): C₈H₁₈N₂O₄S. Molecular weight: 238.30. Sigma catalog no. H3375.

Good luck with your experiments!