How to Make Buffer With a pH Meter

Select buffer solution salts with the correct pH boundary for the reaction. Individual proteins and reactions have specific pH requirements. The requirements are explicitly stated in the reaction protocol, presented in documentation accompanying the protein/sample or recorded in such reference volumes as the Handbook of Chemistry and Physics. An optimal buffer solution's pH should fall as close as possible to the reaction's pH unit and should never exceed plus or minus 1 pH value. Buffer solution salts are available as a package or can be mixed from raw components following widely available recipes.

Pour the buffer solution into a 1-liter beaker. Add 1 liter of distilled water. Put a stirring bar into the beaker and place the beaker upon a stirring plate. Activate the stirring plate at a low to medium setting. Stir until no buffer solution crystals remain visible.

Place 100 mL beaker under the pH meter's testing needle. Clean the needle by spraying it with distilled water. The beaker will catch the run off. Calibrate the pH meter using the calibration solutions. Clean the needle again. Dispose of the runoff contents captured in the 100 milliliter beaker.

Bring the pH meter to the stirring plate and 1-liter beaker. Introduce the testing needle into the buffer solution. Push the pH meter's calculation button to determine the solution's pH. If this value is too high or low, the solution requires the following additional steps.

Place a fresh micropipette tip on the micropipetter. Activate the stirring plate at low speed. If the pH is too high, use the micropipetter to add one drop at a time of hydrochloric acid to the solution. Allow the stirring plate to mix the solution and measure the pH. Repeat the process until the solution pH is the necessary value. If the pH is too low, repeat this step using sodium hydroxide instead of hydrochloric acid.