0.1 M Phosphate Buffer Solution Preparation
Introduction
Phosphate buffer solutions are commonly used in biochemical and molecular biology experiments to maintain a stable pH and provide a buffering capacity to the reaction mixture. In this article, we will discuss the preparation of a 0.1 M phosphate buffer solution, which is a widely used concentration in many laboratory applications.
Materials
- Sodium phosphate monobasic (NaH2PO4)
- Sodium phosphate dibasic (Na2HPO4)
- Distilled water
Preparation
To prepare a 0.1 M phosphate buffer solution, you will need to calculate the amount of sodium phosphate monobasic and sodium phosphate dibasic required to achieve the desired concentration.
Step 1: Calculate the amount of sodium phosphate monobasic (NaH2PO4)
The molecular weight of NaH2PO4 is 119.98 g/mol. To prepare a 0.1 M solution, you will need:
- 0.1 mol/L x 119.98 g/mol = 11.998 g of NaH2PO4 per liter of solution
Step 2: Calculate the amount of sodium phosphate dibasic (Na2HPO4)
The molecular weight of Na2HPO4 is 141.96 g/mol. To prepare a 0.1 M solution, you will need:
- 0.1 mol/L x 141.96 g/mol = 14.196 g of Na2HPO4 per liter of solution
Step 3: Weigh and dissolve the reagents
Weigh out the calculated amounts of NaH2PO4 and Na2HPO4 using a balance. Dissolve the reagents in approximately 800 mL of distilled water in a beaker.
Step 4: Adjust the pH
Use a pH meter to adjust the pH of the solution to the desired value. The pH of a phosphate buffer solution can be adjusted by adding either NaH2PO4 (to lower the pH) or Na2HPO4 (to raise the pH).
Step 5: Filter and store the solution
Filter the solution through a 0.2 μm filter membrane to remove any impurities. Store the solution in a clean, sterile container at room temperature.
Tips and Variations
- To prepare a more concentrated or diluted phosphate buffer solution, simply adjust the amounts of NaH2PO4 and Na2HPO4 accordingly.
- You can also add other reagents, such as sodium chloride (NaCl), to the phosphate buffer solution to create a more complex buffer system.
- Phosphate buffer solutions can be stored for several months at room temperature, but it is recommended to prepare fresh solutions regularly to ensure optimal performance.
By following these steps, you can easily prepare a 0.1 M phosphate buffer solution for your laboratory experiments.
