What is the chemical composition of gel elution buffer?
If it is ion exchange gel chromatography, the concentration of the salt will be higher in the elution buffer when compared to the loading buffer. If it is affinity chromatography, you need to use an elution buffer that can dissociate the bound molecule eg. alpha methyl pyranoside is used at a high concentration to elude out complex mannose containing carbohydrates from the lectin (concanvalin) sepharose column. The chemical composition of an elution buffer could have different pH, salt concentration and chemicals that could compete and release the bound molecule of interest on the column.
