pKa Values of Common Capillary Electrophoresis Buffers
The dissociation constant (pK) is the pH at which 50% of a compound is protonated. Some compounds will have more than one pK. This can be the same or differ from the compound’s pI or isoelectric point.
| Buffer | pK |
|---|---|
| Acetate | 4.75 |
| Boric (pK1) | 9.14 |
| Boric (pK2) | 12.74 |
| Boric (pK3) | 13.80 |
| CAPS | 10.40 |
| Citrate (pK2) | 4.76 |
| Citric (pK2) | 5.95 |
| Citric (pK3) | 6.39 |
| Citric (pKa1) | 3.14 |
| Glycine (pK2) | 9.6 |
| Glycine (pK1) | 2.3 |
| Maleic (pK1) | 1.9 |
| Maleic (pK2) | 6.2 |
| Malic (pK1) | 3.40 |
| Malic (pK2 | 5.11 |
| MES | 6.15 |
| Phosphate (pK1) | 2.15 |
| Phosphate (pK2) | 7.21 |
| Phosphate (pK3) | 12.67 |
| Sodium Benzoate | 4.2 |
| Sulfurous (pK1) | 1.81 |
| Sulfurous (pK2) | 6.91 |
| Tetra Borate (pK1) | 4.00 |
| Tetra Borate (pK2) | 9.00 |
| Tris | 8.3 |