PB (0.1 M phosphate buffer pH 7.2)

MATERIALS

METHOD

• 1. Prepare sodium phosphate dibasic stock (0.5 M) by dissolving 35.5 g of sodium phosphate dibasic in a final volume of 500 mL of H₂O.

  Some crystallization will occur when the solution is stored at 4ºC. Warm on a hot plate and stir until the crystals dissolve.

• 2. Prepare sodium phosphate monobasic stock (0.5 M) by dissolving 30 g of anhydrous sodium phosphate monobasic in a final volume of 500 mL of H₂O.

• 3. Prepare 0.1 M sodium phosphate dibasic: Put 80 mL of sodium phosphate dibasic stock (0.5 M) from Step 1 in a beaker and add H₂O to give a final volume of 400 mL.

• 4. Prepare 0.1 M sodium phosphate monobasic: Put 30 mL of sodium phosphate monobasic stock (0.5 M) from Step 2 in a beaker and add H₂O to give a final volume of 150 mL.

• 5. Bring the 0.1 M sodium phosphate dibasic solution from Step 3 to pH 7.2 by adding as much as needed of the 0.1 M sodium phosphate monobasic solution from Step 4.

  The resulting solution is 0.1 M phosphate buffer pH 7.2.