Biochemical Techniques and Instrumentation (1+2)

2.3.5. Eluent buffers

There are anionic and cationic buffers for the elution of compounds.

1. Cationic buffers are tris, pyridine and alkyl amines. They are used with anion exchangers.
2. Anionic buffers are acetate, barbiturate and phosphate. They are used with cationic exchangers.

The pH of the buffer selected as eluent should be one pH unit above or below the isotonic point of the molecule. The initial pH and ionic strength should allow the binding of the molecules to the exchanger. A buffer of the lowest ionic strength should be initially used as it ensures that minimum binding of contaminants to the exchanger. If gradient elution is used, initial conditions should allow all the sample compounds to bind at the top of the column.