in western blotting the non-specific sites on the membrane can be blocked by
a dilute solution of protein -- typically 3 -- 5 % bovine serum albumin ( BSA ) or non-fat dry milk ( both are inexpensive ) in tris - buffered saline ( TBS ) or I - Block , with a minute percentage ( 0.1 % ) of detergent such as Tween 20 or Triton X-100