Abstract: The present disclosure is directed to methods for the preparation of immunoadsorption matrices having IgG molecules adsorbed thereto in a preferred configuration, i.e., adsorbed to the matrix by their (Fc) rather than F(ab) portions. IgG molecules, are selected such that the F(ab) portion of the IgG fraction adsorbed has a more acidic or basic net isoelectric point or pI range than the F(c) end of the molecule, depending on the characteristics of the adsorption surface. For negatively charged surfaces, IgG molecules having relatively alkaline F(c) portions are selected. For positively charged surfaces, IgG with relatively acidic F(c) portions are selected. Additional selection criteria include pI fractionation to provide fractions having well defined pI characteristics as defined by "non-overlap" or "pI range" of F(c) and F(ab) portions pI's. Methods disclosed are particularly well suited to the preparation of colloidal gold immunostains.