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Phosphate buffer
Phosphate buffer is often used for column chlomatography. But it is not an ideal buffer for biological assays because phosphate can act as either a substrate or a regulation factor of enzymes. Besides, the buffering ability decreases significantly at low pH. Use Good's buffers for biological assays.
Sørensen's 0.1M buffer
The preparation of phosphate buffer by Sørensen's method.
- Sørensen, S.P.L.: Biochem Z. 21, 131 (1909) and Biochem. Z. 22, 352 (1909)
- Gomori, G.: Methods Enzymol. Vol. 1, 138 (1955)
Mix the following volumes of A and B, and add equal volume of H2O to result [phosphate] = 0.1M.
| Stock solution A | 0.2 M NaH2PO4 |
|---|---|
| Stock solution B | 0.2 M Na2HPO4 |
| pH | 5.8 | 6.0 | 6.2 | 6.5 | 6.6 | 6.7 | 6.8 | 6.9 | 7.0 | 7.1 | 7.2 | 7.3 | 7.4 | 7.5 | 7.8 | 8.0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A (ml) | 92.0 | 87.7 | 81.5 | 68.5 | 62.5 | 56.5 | 51.0 | 45.0 | 39.0 | 33.0 | 28.0 | 23.0 | 19.0 | 16.0 | 8.5 | 5.3 |
| B (ml) | 8.0 | 12.3 | 18.5 | 31.5 | 37.5 | 43.5 | 49.0 | 55.0 | 61.0 | 67.0 | 72.0 | 77.0 | 81.0 | 84.0 | 91.5 | 94.7 |
Last modified: 2013/06/09 19:09
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