Volume 296, June 2009
Volume 65, June 2009
Pages F1521–F1529. Nguyen MK, Kao L, and Kurtz I. Calculation of the equilibrium pH in a multiple-buffered aqueous solution based on partitioning of proton buffering: a new predictive formula. Am J Physiol Renal Physiol 296: F1521–F1529. On p. F1524–F1527, there are typographical errors in the reported data in Experiment 2 in Tables 1 and 2. The corrected data in Experiment 2 in Tables 1 and 2, which appear in bold, are shown below. Of note, the reported pH values in Table 1 are correct as originally stated; this can be easily verified by entering the values listed here into our mathematical model and solving for pH. In Table 1, it should be noted that total volume for the solution for the initial data set in Experiment 4 was 20.04 ml because more HCl was initially needed to titrate the pH of the solution to the calibration range of our pH measurements. Thereafter, the total volume changed in increments of 0.02 ml. Similarly, the total volume of the solution for the initial data set in Experiments 5 and 6 was 20.04 ml.
Table 1.
Predicted pH vs. measured pH
| Experiment 2 | [H+]i, mol/l | [OH−]I, mol/l | Kw′ | [HA]i, mol/l | [A−]i, mol/l | Ka′ | [HB]i, mol/l | [B−]i, mol/l | Kb′ | Predicted pHe | Measured pHe |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Buffers: OH−, PIPES, and MES | |||||||||||
| 1.0139E-03 | 1.2011E-07 | 1.1070E-14 | 3.4384E-03 | 6.5516E-03 | 1.7544E-07 | 1.0503E-03 | 8.9397E-03 | 7.8367E-07 | 6.91 | 6.89 | |
| 1.0129E-03 | 7.7547E-08 | 1.1052E-14 | 4.4748E-03 | 5.5052E-03 | 1.7517E-07 | 1.5365E-03 | 8.4436E-03 | 7.8244E-07 | 6.73 | 6.73 | |
| 1.0120E-03 | 5.3650E-08 | 1.1038E-14 | 5.3859E-03 | 4.5842E-03 | 1.7495E-07 | 2.0763E-03 | 7.8938E-03 | 7.8145E-07 | 6.58 | 6.59 | |
| 1.0110E-03 | 3.8866E-08 | 1.1023E-14 | 6.1612E-03 | 3.7990E-03 | 1.7470E-07 | 2.6531E-03 | 7.3071E-03 | 7.8036E-07 | 6.45 | 6.45 | |
| 1.0101E-03 | 2.8156E-08 | 1.1007E-14 | 6.8780E-03 | 3.0723E-03 | 1.7446E-07 | 3.3220E-03 | 6.6283E-03 | 7.7927E-07 | 6.31 | 6.31 | |
| 1.0093E-03 | 2.0397E-08 | 1.0990E-14 | 7.5101E-03 | 2.4302E-03 | 1.7419E-07 | 4.0649E-03 | 5.8755E-03 | 7.7806E-07 | 6.16 | 6.16 | |
| 1.0085E-03 | 1.4440E-08 | 1.0977E-14 | 8.0796E-03 | 1.8509E-03 | 1.7398E-07 | 4.9081E-03 | 5.0224E-03 | 7.7714E-07 | 6.01 | 6.01 | |
| 1.0077E-03 | 1.0223E-08 | 1.0967E-14 | 8.5362E-03 | 1.3844E-03 | 1.7382E-07 | 5.7530E-03 | 4.1677E-03 | 7.7644E-07 | 5.84 | 5.85 | |
| 1.0072E-03 | 7.0724E-09 | 1.0958E-14 | 8.9110E-03 | 9.9983E-04 | 1.7368E-07 | 6.6020E-03 | 3.3088E-03 | 7.7579E-07 | 5.66 | 5.66 | |
| 1.0070E-03 | 4.5664E-09 | 1.0949E-14 | 9.2322E-03 | 6.6881E-04 | 1.7353E-07 | 7.4804E-03 | 2.4206E-03 | 7.7514E-07 | 5.41 | 5.40 | |
| 1.0078E-03 | 2.5094E-09 | 1.0948E-14 | 9.5125E-03 | 3.7870E-04 | 1.7351E-07 | 8.3978E-03 | 1.4934E-03 | 7.7505E-07 | 5.00 | 5.02 |
Table 2.
Partitioning of H+ among buffer pairs
| Experiment 2 | [H+]i, mol/l | H+ buffered by OH−, mol/l | H+ buffered by PIPES, mol/l | H+ buffered by MES, mol/l | [H+]e mol/l |
|---|---|---|---|---|---|
| Buffers: OH−, PIPES, and MES | |||||
| 1.0139E-03 | 3.0854E-08 | 6.9904E-04 | 3.1469E-04 | 1.2403E-07 | |
| 1.0129E-03 | 1.7647E-08 | 6.4484E-04 | 3.6789E-04 | 1.8451E-07 | |
| 1.0120E-03 | 1.1443E-08 | 5.8798E-04 | 4.2372E-04 | 2.6153E-07 | |
| 1.0110E-03 | 8.0677E-09 | 5.3193E-04 | 4.7874E-04 | 3.5791E-07 | |
| 1.0101E-03 | 5.8513E-09 | 4.7350E-04 | 5.3613E-04 | 4.9351E-07 | |
| 1.0093E-03 | 4.3700E-09 | 4.1671E-04 | 5.9186E-04 | 6.8574E-07 | |
| 1.0085E-03 | 3.3087E-09 | 3.6171E-04 | 6.4576E-04 | 9.8617E-07 | |
| 1.0077E-03 | 2.6019E-09 | 3.1530E-04 | 6.9101E-04 | 1.4391E-06 | |
| 1.0072E-03 | 2.1015E-09 | 2.7603E-04 | 7.2895E-04 | 2.2045E-06 | |
| 1.0070E-03 | 1.7225E-09 | 2.4180E-04 | 7.6131E-04 | 3.8501E-06 | |
| 1.0078E-03 | 1.4223E-09 | 2.1116E-04 | 7.8652E-04 | 1.0071E-05 |