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Helpful Hints For Capillary Electrophoresis
pKa Values of Common HPCE Buffers
The dissociation constant (pK) is the pH at which 50% of a compound is protonated. Some compounds will have more
than one pK. This can be the same or differ from the compound’s pI or isoelectric point.
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Buffer
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pK
|
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Acetate
|
4.75
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Boric (pK1)
|
9.14
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Boric (pK2)
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12.74
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Boric (pK3)
|
13.80
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CAPS
|
10.40
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Citrate (pK2)
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4.76
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Citric (pK2)
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5.95
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Citric (pK3)
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6.39
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Citric (pKa1)
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3.14
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Glycine (pK2)
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9.6
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Glycine (pK1)
|
2.3
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Maleic (pK1)
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1.9
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Maleic (pK2)
|
6.2
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Malic (pK1)
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3.40
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Malic (pK2)
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5.11
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MES
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6.15
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Phosphate (pK1)
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2.15
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Phosphate (pK2)
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7.21
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Phosphate (pK3)
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12.67
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Sodium Benzoate
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4.2
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Sulfurous (pK1)
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1.81
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Sulfurous (pK2)
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6.91
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Tetra Borate (pK1)
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4.00
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Tetra Borate (pK2)
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9.00
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Tris
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8.3
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