Protein concentrators - (May/23/2004 )

Hi,

I have been using Centricon and Amicon Ultra devices for concentrating the protein. I see a loss of ~50% during the process. The protein does not flow through but sticks to the membrane. I have tried passivation and that helps 10-15% only. Is there a better device that I can use. I typically work with 10-30ml which I need to concentrate 6-8 fold.

Any input will be helpful.

I tend to use Vivascience spin filters to concentrate my samples. The most loss I ever had was 5%. I also found it handy to use to exchange buffers.