Biochemical Techniques and Instrumentation

2.3.6. Elution

Gradient elution is most common than isocratic elution. In isocratic elution, the sample volume is 1-5% of bed volume and in gradient elution, large volumes can be applied. Continuous or stepwise pH and ionic strength gradients can be employed but a continuous gradient tends to give better resolution. During the elution with an anion exchanger, pH gradient decreases and ionic strength increases, whereas with a cation exchanger, both the pH and ionic gradients increase.