This is the method that I saw in a paper we are using as basis:
low MW tannins were eluted with acetone/water (3:7; v/ v; Fraction 1) and higher MW tannins with acetone/ water (1:1; v/v; Fraction 2)
Normally, how much would the volume of each eluent be if the fractionation used 2 eluents?
I saw other methods where they collected 2.6-ml fractions, but the paper only used one eluent.