What is the proper pH for the buffered solution used to perform serum protein electrophoresis?

What is the proper pH for the buffered solution used to perform serum protein electrophoresis?

• A. 5.6
• B. 7.6
• C. 8.6
• D. 9.6

Answer: (C)

In serum protein electrophoresis, you want the major proteins to carry a net negative charge so they migrate toward the positive electrode and separate based on subtle differences in their charge and size. An alkaline buffer around pH 8.6 achieves this: most serum proteins have pI values well below 8.6, so they are negatively charged at this pH and form well-resolved bands (albumin moving fastest, with the other fractions following in distinct zones). If the pH were much lower, many proteins would carry less negative charge (or even positive charges), reducing resolution. If it were much higher, the pattern could become unstable or distorted. Therefore, the proper buffered pH for SPEP is about 8.6.

In serum protein electrophoresis, you want the major proteins to carry a net negative charge so they migrate toward the positive electrode and separate based on subtle differences in their charge and size. An alkaline buffer around pH 8.6 achieves this: most serum proteins have pI values well below 8.6, so they are negatively charged at this pH and form well-resolved bands (albumin moving fastest, with the other fractions following in distinct zones). If the pH were much lower, many proteins would carry less negative charge (or even positive charges), reducing resolution. If it were much higher, the pattern could become unstable or distorted. Therefore, the proper buffered pH for SPEP is about 8.6.