100 mm Sodium Phosphate Buffer Preparation
Introduction
Sodium phosphate buffer is a commonly used buffer solution in molecular biology, biochemistry, and biotechnology laboratories. It is used to maintain a stable pH and ionic strength in various experiments, such as protein purification, enzyme assays, and molecular biology reactions. In this article, we will discuss the preparation of 100 mm sodium phosphate buffer.
Materials
- Sodium phosphate monobasic (NaH2PO4)
- Sodium phosphate dibasic (Na2HPO4)
- Distilled water
- pH meter
Protocol
Step 1: Prepare Stock Solutions
Prepare two stock solutions:
- Stock solution A (NaH2PO4): Weigh 12.0 g of sodium phosphate monobasic and dissolve it in 100 mL of distilled water.
- Stock solution B (Na2HPO4): Weigh 17.8 g of sodium phosphate dibasic and dissolve it in 100 mL of distilled water.
Step 2: Mix Stock Solutions
To prepare 100 mm sodium phosphate buffer, mix the stock solutions in a specific ratio. You can use the following formula:
pH 7.0: Mix 39 mL of stock solution A with 61 mL of stock solution B. pH 7.4: Mix 35 mL of stock solution A with 65 mL of stock solution B.
Adjust the volume of the mixture to 100 mL with distilled water.
Step 3: Check pH
Use a pH meter to check the pH of the buffer solution. Adjust the pH by adding small amounts of either stock solution A or stock solution B.
Step 4: Filter Sterilize
Filter the buffer solution through a 0.2 μm filter to remove any impurities. Autoclave the solution for 15-20 minutes to sterilize it.
Tips and Variations
- Use high-quality reagents: Use high-purity sodium phosphate salts to ensure the stability and accuracy of the buffer solution.
- Adjust pH: Adjust the pH of the buffer solution according to your specific needs.
- Concentration: You can prepare buffer solutions of different concentrations, such as 10 mm, 50 mm, or 200 mm, by adjusting the amount of stock solutions.
- Other buffer systems: You can also prepare other buffer systems, such as Tris-HCl or HEPES, using a similar protocol.
Conclusion
In this article, we have discussed the preparation of 100 mm sodium phosphate buffer solution. This buffer solution is commonly used in various laboratory applications and can be easily prepared by mixing stock solutions of sodium phosphate monobasic and dibasic. By following this protocol, you can ensure the accuracy and stability of your buffer solution.
