protein purifiacation - (Jan/24/2005 )

hi,
I am trying to purify a 100KDa protein using a Quiagen column and i am facing problem in the step of elution.
I am purifying under denaturing comditions using Urea ,Na P,Tris -cl buffers
I tried eluting at lower PH , pH4.5
also tried eluting using imidazole but there is no sign of elution?
can there be problem with the columns i am using?

Need guidance
thanks in advance

Please provide more details.

What qiagen column you are using ?

I presume you are using Ni NTA, as you are mentioning Imidazole and Lowering pH etc.,