Bio-Rad Aurum Ion Exchange Mini Kits - Manual (Page 5)

Table 3. Common buffers for ion exchange chromatography.
Cation Buffering Range Anion Buffering Range
Acetic acid 4.8–5.2 Bicine 7.6–9.0
Citric acid 4.2–5.2 Bis-Tris 5.8–7.2
HEPES 7.6–8.2 Diethanolamine 8.4–8.8
MES 5.5–6.7 Diethylamine 9.5–11.5
MOPSO 6.5–7.9 L-histidine 5.5–6.0
Phosphate 6.7–7.6 Imidazole 6.6–7.1
PIPES 6.1–7.5 Pyridine 4.9–5.6
TES 7.2–7.8 Tricine 7.4–8.8
Tricine 7.8–8.9 Triethanolamine 7.3–8.0
Tris 7.5–8.0
Sample Preparation
Proper adjustment of the sample pH and ionic strength is critical for consistent
and reproducible chromatography. For best results, the sample should be
exchanged into the loading buffer or diluted to the buffer’s concentration.
Buffer exchange can be accomplished using Micro Bio-Spin
™ 6 (catalog
#732-6221) or Bio-Spin ® 6 (catalog #732-6227) columns, Econo-Pac ® Bio-Gel ®
P-6 cartridges (catalog #732-0011), or Econo-Pac 10DG desalting columns
(catalog #732-2010). The correct product to use will be determined by the
volume of the sample. Always centrifuge or filter the sample (0.2–0.45 µm
filter) to remove particulates.
Use of Aurum Ion Exchange Columns to Concentrate Protein
Solutions
The Aurum AEX and CEX columns are not only purification tools but also can
be used to concentrate target proteins of interest in dilute solutions, a critical
factor for subsequent analyses such as 2-D electrophoresis. Protein solutions
of 0.1–0.2 mg/ml can be concentrated 30–70-fold using the appropriate resin
with little loss of protein.
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