u*****s 发帖数: 172 | 1 My answer for your reference.
Proteins and column both have charges.
Proteins can bind to the column by electrostatic interaction (so-called
non-specific binding). Of course this is not what you expect.
Assume Protein 1 is what you want, protein 2 is impurity.
If there is sodium chloride in the solution, sodium or chloride ion can
compete
with proteins to bind to column. So protein 2 will be removed from the column.
Although protein 1 is also decreased, the specific binding between histadine
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