I received a custom rabbit polyclonal purified antibodies (3 in total) from Thermo Fisher. When I first received them, they worked great, now there is a precipitate and the binding is decreasing for the antibody. The customer service rep told me I can try adding 0.5-1.05% BSA, but that seemed to have little effect. I have also heard of using potassium salt, but I am not familiar with this method to regain antibody activity. Can anyone give me any suggestions? Thanks.