0.1M Sodium Phosphate Buffer Preparation
Introduction
Sodium phosphate buffer is a commonly used buffer solution in various biochemical and molecular biology applications. It is essential to prepare a sodium phosphate buffer of accurate concentration and pH to ensure the reliability of experimental results. In this article, we will describe the preparation of 0.1M sodium phosphate buffer.
Materials
- Sodium phosphate monobasic (NaH2PO4)
- Sodium phosphate dibasic (Na2HPO4)
- Distilled water
- pH meter
Preparation
To prepare 0.1M sodium phosphate buffer, follow these steps:
Step 1: Calculate the required amounts of NaH2PO4 and Na2HPO4
The ratio of NaH2PO4 to Na2HPO4 is critical in determining the pH of the buffer solution. For a 0.1M sodium phosphate buffer, the required amounts of NaH2PO4 and Na2HPO4 can be calculated using the following formula:
NaH2PO4 (g) = (0.1 M x molecular weight of NaH2PO4) / 2 Na2HPO4 (g) = (0.1 M x molecular weight of Na2HPO4) / 2
Where the molecular weights of NaH2PO4 and Na2HPO4 are 119.98 g/mol and 141.96 g/mol, respectively.
Step 2: Weigh the calculated amounts of NaH2PO4 and Na2HPO4
Accurately weigh the calculated amounts of NaH2PO4 and Na2HPO4 using a balance.
Step 3: Dissolve NaH2PO4 and Na2HPO4 in distilled water
Dissolve the weighed NaH2PO4 and Na2HPO4 in approximately 90% of the final volume of distilled water.
Step 4: Adjust the pH
Use a pH meter to adjust the pH of the buffer solution to the desired value (e.g., pH 7.0). Add NaOH or HCl dropwise to adjust the pH.
Step 5: Add distilled water to the final volume
Add distilled water to the buffer solution to the final volume (e.g., 1 liter).
Tips and Precautions
- Use high-purity reagents: To ensure the quality of the buffer solution, use high-purity NaH2PO4 and Na2HPO4.
- Avoid contamination: Use sterile equipment and work in a clean environment to minimize contamination risks.
- Store the buffer solution properly: Store the prepared buffer solution in a clean, sterile container at 4°C or -20°C.
Conclusion
The preparation of 0.1M sodium phosphate buffer is a straightforward process that requires attention to detail and accurate calculations. By following these steps, you can prepare a high-quality buffer solution essential for various biochemical and molecular biology applications.
