Zwitterionic Buffer

 Buffer

 Structure and Name

 MW

 pKa at 20 °C (D/°C)

 useful pH range
 ACES

 

 N-(2-acetamido)-2-aminoethanesufonic acid

 182.2

 6.88 (-0.020)

 6.4 - 7.4
 ADA

 

 N-(2-acetamido)iminodiacetic acid

 190.2

 6.62 (-0.011)

 6.4 - 7.4
 BES

 

 N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid

 213.3

 7.17 (-0.016)

 6.6 - 7.6
 Bicine

 

 N,N-bis(2-hydroxyethyl)glycine

 163.2

 8.35 (-0.018)

 7.8 - 8.8
 CAPS

 

 3-(cyclohexylamino)-1-propanesulfonic acid

 221.3

 10.4 (0.032)

 9.7 - 11.1
 CHES

 

 2-(cyclohexylamino)-1-ethanesulfonic acid

 207.1

 9.55 (-0.011)

 9.0 - 10.1
 HEPES

 

 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid

 238.3

 7.55 (-0.014)

 7.0 - 8.0
 HEPPS (EPPS)

 

 4-(2-hydroxyethyl)piperazine-1-propanesulfonic acid

 252.3

 8.0 (-0.011)

 7.6 - 8.6
 MES

 

 2-morpholinoethanesulfonic acid monohydrate

 213.3

 6.15 (-0.011)

 5.8 - 6.5
 MOPS

 

 3-morpholinopropanesulfonic acid

 209.3

 7.2 (-0.011

 6.5 - 7.9
 PIPES

 

 piperazine-1,4-bis(2-ethanesulfonic acid)

 302.4

 6.82 (-0.009)

 6.4 - 7.2
 TAPS

 

 N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid

 243.3

 8.4 (0.018)

 7.7-9.1
 TES

 

 N-[tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid

 229.3

 7.5 (-0.020)

 7.0 - 8.0
 Tricine

 

 N-[tris(hydroxymethyl)methyl]-glycine

 179.2

 8.15 (-0.021)

 7.6 - 8.8
 Tris

 

 tris(hydroxymethyl)aminomethane

 121.1

 (157.6)

 8.08 (-0.028)

 7.0 - 9.0
         
         

     

 Non-Zwitterionic Buffer
 

 Compound

 Formula

 MW

 Solubility

 pKa at 20 °C
     

 g/100 mL of H2O at 20 °C

 1

 2

 3
 Boric Acid 

 H3BO3

 61.8

 6.4

 9.14

 12.74

 13.8

 Citric Acid, anhydrous

 tri sodium salt

 C6H8O7

 Na3C6H5O7 (H2O)2

 192.4

 294.1

 146.0

 72.0

 3.14

 3.09

 4.77

 4.75

 6.39 (18 °C)

 5.41 (18° C)
 Imidazole

 C4H4N2

 68.1

 very soluble

 6.95 (25 °C)
    
 Potassium Phosphate, monobasic 

 KH2PO4

 136.1

 136.1

 2.12

7.21
  12.67 (25°C)
 Potassium Phosphate, dibasic

 K2HPO4

 174.2

 174.2

 2.12

 7.21
  12.67 (25 °C)
 Potassium Hydrogen Phthalate

 C8H5KO4

 204.2

 204.2

 2.89

 5.51 (25 °C)
  

 Sodium Acetate, anhydrous

 trihydrate

 CH3CO2Na

CH3CO2Na (H2O)3

82.0

136.1

119.0 (0 °C) 

76.2 (0 °C)

4.75 (25 °C)
    
 Sodium Cacodylate

(CH3)2AsO2Na (H2O)3

 214.0

200

6.21
    

 Sodium Carbonate, anhydrous

decahydrate

 Na2CO3

Na2CO3 (H2O)10

 106.0

286.1

 7.1 (0° C)

 21.5 (0° C)

 6.37
    
 Sodium Phosphate, monobasic

 NaH2PO4 (H2O)2

156.0

very soluble

 2.12

 7.21

  12.67

 Sodium Phosphate, dibasic, anhydrous

 dihydrate

 dodecahydrate

 Na2HPO4

 Na2HPO4 (H2O)2

 Na2HPO4 (H2O)12

 142.0

 178.0

 358.1

 ---

 60.0

 4.2

 2.12

 7.21

 12.67 (25° C)
 Sodium Hydrogen Carbonate

 NaHCO3

 84.0

 9.6

  6.37

 10.25
  

 Sodium Tetraborate, anhydrous

 decahydrate

 Na2B4O7

 NaB4O7 (H2O)10

 201.2

 381.4

 1.1 (0° C)

 2.0 (0° C)

 9.14

 12.74

 13.80