void volume

[emmaburbridge]

I am using a BioSep S2000 column which has a range of 1 -300kDa. Anything with a MW greater than this has been running in the void volume as expected. I have just run a new sample which should run in the void volume and two peaks have appeared instead of one.
Does anyone have any ideas why this might happen

[PJ8]

Isomers? Impurity?
I've no doubt people will ask for more details to be able to answer that like what you are trying to seperate (in general terms)?

[anupama]

Increased run time and decreased flow rate & see after what happened?
What is your method?

[unmgvar]

emmaburbridge,

you are talking of compounds that are in the exclusion limit of your colunm.
this means that they are bigger then 300Kda. i don't think that anything else then that can be said.
if those compounds are of any interest for you then there is no reason for you to run them in exclusion part of that column.
you must change to a column which can deal with the size of your compounds only then can you start to try and characterize them

are you running a system with multiple detectors or just RI?