Can someone please explain what is the difference between the bead volume and the column volume? If they are the same it says on the pd-10 column booklet that the bed volume is 8.3 so assuming that the value is right they also say that the smaller molecule AKA NaCl will elute at the end of the column volume but in the elution profile plot the salt is eluting as late as 12 ml this doesn't make sense The reason for my previous question is that the post doc in my lab says that dtt will be eluted in fraction 4 which i am not sure if thats the right so basically fraction one is the first 0.5 ml after i load my sample to the column and adjust the volume to 2.5 i kinda assumed that 2.5 ml is the void volume and i am adjusting to 2.5 so i push my sample down the column to the bottom to be eluted am I right about this?