Dye for Sephadex column

[Pete's Person]

Hi,

A lab I worked in previously used a blue dye for their sephadex 
columns when seperating labeled probe from unicorporated nucleotides. 
The dye allowed the correct (labelled) fraction to be collected, as it 
colored the longer fragments dark blue and left the unicorporated nts 
a light blue. I can't remember the name of the dye, though, or it's 
composition - can anyone help me out?

Thanks in advance.

petester at valise.com