Buffer & Solution Recipe Generator
Step-by-step recipes and pH adjustment for PBS, Tris-HCl, HEPES, SDS-PAGE, TAE and agarose gels.
How it works
Recipes are generated from target molarity, final volume and desired pH, returning the mass of each solid component and the acid or base needed for adjustment. Buffering capacity is strongest within roughly one pH unit of the buffer’s pKa, and the tool flags requests that fall outside that useful range.
Frequently asked questions
How do I make a Tris buffer at a specific pH?
Dissolve Tris base to your target molarity in slightly less than the final volume of water, then titrate to the target pH with hydrochloric acid before making up to volume. Tris has a pKa near 8.1, so it buffers usefully from about pH 7.1 to 9.1. Its pH shifts markedly with temperature — roughly −0.03 pH units per °C — so always adjust it at the temperature at which it will be used.
Why does my buffer pH drift after autoclaving?
Autoclaving drives off dissolved carbon dioxide and can hydrolyse some buffer components, both of which shift pH. Temperature-sensitive buffers such as Tris are affected most. Where possible, autoclave the water and add filter-sterilised buffer afterwards, or check and re-adjust pH once the solution has returned to working temperature.