A guide for the preparation and use of buffers in biological systems

Commonly Used Buffer Media in Biological Research
Krebs-Henseleit bicarbonate buffer, pH 7.4
119 mM NaCl
4.7 mM KCl
2.5 mM CaCl 2
1.2 mM MgSO 4
1.2 mM KH 2
PO 4
25 mM NaHCO 3
pH 7.4 (at 37°C) when equilibrated with 95% O 2
and 5% CO 2
. Adjust the pH
before use.
Hank’s Biocarbonate Buffer, pH 7.4
137 mM NaCl
5.4 mM KCl
0.25 mM Na 2
HPO 4
0.44 mM KH 2
PO 4
1.3 mM CaCl 2
1.0 mM MgSO 4
4.2 mM NaHCO 3
pH 7.4 (at 37°C) when equilibrated with 95% O 2
and 5% CO 2
. Adjust the pH
before use.
Phosphate Buffered Saline (PBS), pH 7.4
150 mM NaCl
10 mM Potassium Phosphate buffer
(1 liter PBS can be prepared by dissolving 8.7 g NaCl, 1.82 g
K 2
HPO 4
.3H 2
O, and 0.23 g KH 2
PO 4
in 1 liter of distilled water.
Adjust the pH before use).
A variation of PBS can also be prepared as follows:
137 mM NaCl
2.7 mM KCl
10 mM Na 2
HPO 4
1.76 mM KH 2
PO 4
22