Question

What are some possible errors which affect %yield in the column chromatography experiment? (No TLC)

Answer 1

Sometimes the compound are very polar and if they are not predissolved properly in the silica gel, it may recrystalize in the column and will take much longer time to come. So when we stop the column by analyzing tlc, the product might still be there in the column.

If we are running flash column chromatography and we run a particular solvent system which doesn't separate two compounds properly we will get mixture of two compounds and thus will get loss of pure product.

While collecting the fractions some solvent may spill from tbe collecting vessel like test tubes due to overflow will lead to loss of products.

Sometimes the product get stuck on the walls of collecting vessels, when left, due to evaporation of solvent from top. So when we transfer tge fractions in round bottom flask to be concentrated, we loise those products, that were stuck on the walls of collecting vessel unless they are washed again with right solvent.

When we predissolve the compound in silica gel, some amount of silica gel gets stuck on the side of round bottom flask and thus we loose product when the predissolved compound is being transferred to the column.