I am trying to concentrate a protein using Amicon Ultra centrifugal device. I have done this several times before without any problems.

This time I had a larger volume of my sample so I had to centrifuge consecutively for a total of 2 hours. When I thereafter transferred the sample to another tube I had lost 50% of my protein (nothing was in the filtrate, I checked that). I washed the membrane with fresh PBS and after that I let the column stand in PBS. When I measured the abs 280 nm in the PBS after 1 hour it was quite high.

Has the protein absorbed into the membrane? Has anyone encountered similar problems?

Does anyone have any suggestions of better devices to use for concentration of proteins?

More Anette Martensson's questions See All
Similar questions and discussions