Biomedical Engineering Reference
In-Depth Information
Table 7.2.
Dissociation constant pK (25 °C), dpK/dT, and molecular mass
of buffers
Substance
pK
dpK/dT
M
r
Oxalate (oxalic acid) (pK
1
)
1.27
90.0
Maleate (maleic acid) (pK
1
)
2.00
0
116.1
Phosphate (phosphoric acid) (pK
1
)
2.15
0.0044
98.0
Glycine (pK
1
)
2.35
−0.002
75.1
Phthalate (phthalic acid) (pK
1
)
2.95
166.1
Glycylglycine (pK
1
)
3.12
132.1
Malate (malic acid) (pK
1
)
3.40
134.1
Formiate (formic acid)
3.75
0
46.0
Barbituric acid (pK
1
)
4.04
128.1
Succinate (succinic acid) (pK
1
)
4.21
−0.0018
118.1
Oxalate (oxalic acid) (pK
2
)
4.27
90.0
Acetate (acetic acid)
4.75
0.0002
60.0
Citrate (citric acid) (pK
2
)
4.76
−0.0016
192.1
Malate (malic acid) (pK
2
)
5.13
134.1
Pyridine
5.23
−0.014
79.1
Phthalate (phthalic acid) (pK
2
)
5.41
166.1
Piperazine (pK
2
)
5.55
−0.015
86.1
Succinate (succinic acid) (pK
2
)
5.64
0
118.1
Malonate (malonic acid) (pK
2
)
5.70
104.1
Histidine (pK
2
)
5.97
−0.017
155.2
Maleate (maleic acid) (pK
2
)
6.07
116.1
MES (2-morpholinoethanesulfonic acid)
6.10
−0.011
195.2
Cacodylate (cacodylic acid. dimethy-
larsinic acid)
6.27
138.0
Carbonate (carbonic acid) (pK
1
)
6.35
−0.0055
62.0
Citrate (citric acid) (pK
3
)
6.40
0
192.1
BIS-Tris (bis(2-hydroxyethyl) imino-
tris(hydroxymethyl)-methane)
6.46
−0.02
209.5
ADA (N-carbamoylmethyl-iminodiacetic
acid)
6.59
−0.011
190.2
PIPES (1.4-piperazine-bis-ethane sulfonic
acid)
6.76
−0.0085
302.4
ACES (N-(2-acetamido)-2-
aminoethanesulfonic acid)
6.78
−0.02
182.2
BIS-Tris Propane (1.3-bis[tris(hydroxy-
methyl)- methylamino]-propane)
(pK
1
)
6.80
−0.028
282.3
Imidazole
6.95
−0.02
68.1
MOPSO (3-(N-morpholino)-2-
hydroxypopanesulfonic acid)
6.95
−0.015
225.3
BES (2-[bis(2-hydroxyethyl)-amino]-
ethansulfonsäure)
7.09
−0.016
213.3
Phosphate (phosphoric acid) (pK
2
)
7.21
−0.0028
98.0
