Bio-Rad ENrich™ High-Resolution Ion Exchange Columns - Manual (Page 8)

4 ENrich Instruction Manual
Table 2. Buffers for ion exchange chromatography.
Anion Exchange — ENrich Q
pH
Range
Buffer MW pKa @
25°C
Counter-Ion pKa/°C
5.0–6.0 Piperazine 86.1 5.7 Cl-/HCOO – –0.015
5.0–6.0 L-histidine 155.2 6.15 CI – –
5.8–7.2 Bis-Tris 209.2 6.5 CI – –0.017
6.4–7.3 Bis-Tris propane 282.3 6.8,9 CI – –
7.3–8.3 Triethanolamine 149.2 7.8 CI-/CH3COO – –0.02
7.6–8.6 Tris 121.1 8.1 CI – –0.031
8.4–8.8 Diethanolamine 105.1 8.9 CI – –0.025
9.0–9.9 Ethanolamine 61.1 9.5 CI – –0.029
9.8–10.3 1,3-diamino-
propane
74.1 10.5 CI – –0.023
Cation Exchange — ENrich S
pH
Range
Buffer MW pKa @
25°C
Counter-Ion pKa/°C
3.6–4.3 Lactic acid 90.1 3.8 Na + –
4.2–5.2 Citric acid 192.1 3.1 Na + –
5.5–6.7 MES 195.2 6.1 Na + –0.011
6.1–7.5 PIPES 302.4 6.8 Na + –0.009
6.5–7.9 MOPS 209.3 7.2 Na + –0.006
6.7–7.6 Phosphate 120/142 7.2 Na + –0.003
6.8–8.2 TES 229.2 7.4 Na + –0.002
6.8–8.2 HEPS 238.3 7.5 Na + –0.014
7.4–8.8 Tricine 179.2 8.1 Na + –0.021
Always use buffer components of the highest purity available,
as UV-absorbing impurities may cause baseline disturbances
and interfere with the detection of protein peaks. Always filter
and degas buffers.