premise: The precipitate was washed twice with an 80 % saturated <mask> of * * f , dissolved in a small quantity of 0.1 M neutral phosphate buffer , dialyzed against cold distilled water till free from ammonium ions , and lyophilized using liquid nitrogen .
hypothesis: the proper context for <mask> here should be a homogeneous mixture of two or more substances; frequently (but not necessarily) a liquid solution