License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
A buffer solution has the function of resisting changes in pH even when adding powerful acids or bases. However, in the physiological environment the buffered system also provides cofactors for enzymatic reactions, critical salts and even essential nutrients for cells and tissues. Therefore, when trying to reproduce biological conditions in vitro, we must make the appropriate choice of the buffer. After all, it will provide the appropriate medium in which reactions will occur.
MATERIALS
ph Meter (sensitive)
Deionized Water
Sodium Carbonate
Sodium Bicarbonate
Safety warnings
Wear personal protective equipment: gloves, lab coat and mask.
Before start instructions
Organize your workspace.
Make sure all solutions and equipment are available.
Carbonate-Bicarbonate Buffer
1
Note
pH range: 9.2 to 10.6
(a) 0.1 M Sodium carbonate (anhydrous), 10.6 g L-1 (M.W.: 106.0 g mol-1)
(b) 0.1 M Sodium bicarbonate, 8.4 g L-1 (M.W.: 84.0 g mol-1)
Mix sodium carbonate and sodium bicarbonate solutions in the proportions indicated.
mL of Sodium carbonate
4.0
9.5
16.0
22.0
27.5
33.0
38.5
42.5
mL of Sodium bicarbonate
46.0
40.5
34.0
28.0
22.5
17.0
11.5
7.5
pH
9.2
9.4
9.6
9.8
10.0
10.2
10.4
10.6
2
Adjust the final volume to 200 mL with deionized water.
