A method for immunofixation electrophoresis analysis of a biological sample comprising one or more protein(s), in particular for IFE analysis of immunoglobulin(s) belonging to a class selected amongst IgG, IgA, IgM, IgD and IgE, or a fragment thereof that may be present in said biological sample, comprising the steps of: a. depositing at least one aliquot portion of the biological sample on a deposit area of an electrophoretic gel plate, said sample deposit area being at a position of the gel plate enabling electrophoretic migration of the protein content of the deposited sample towards the anodic side of the gel plate, and b. depositing at least one antibody which is modified to bear additional negative electric charges, said modified antibody having antigenic specificity for a predetermined target immunoglobulin or fragment thereof that may be present in the biological sample and having the capability to form an immunocomplex with said predetermined target immunoglobulin or fragment thereof, wherein the at least one modified antibody is deposited on a deposit area of the electrophoretic gel plate that coincides with the sample deposit area of step a. or is separated from the deposit area of step a., being on the same track but at a position that is more cathodic with respect to the position of the sample deposit area of step a., in particular between the cathodic extremity of the gel plate and the sample deposit area of step a., wherein steps a. and b. can be performed in any order or at the same time when the modified antibody deposit area and the sample deposit area are separated, or, when the modified antibody deposit area and the sample deposit area coincide, the deposit of an antibody according to step b. is carried out before or after the deposit of an aliquot portion of the biological sample according to step a., and c. electrophoresing the gel plate to obtain a protein separation profile of the biological sample deposited in step a., the at least one modified antibody deposited in step b. displacing specifically the predetermined target immunoglobulin or fragment thereof that may be present in the biological sample outside the gamma zone and/or protein profile during the electrophoretic migration, and d. applying at least one capture antibody on appropriate zone(s) of the electrophoresed gel plate, wherein said capture antibody has specificity for a particular antibody isotype, or has specificity for the target immunoglobulin or fragment thereof, or has specificity for a particular antibody isotype and/or target immunoglobulin or fragment thereof as found in an immunocomplex between the target immunoglobulin or fragment thereof and the at least one modified antibody, and permitting its reaction to enable the formation of precipitated and/or detectable immunocomplexes, and e. optionally, staining the immunocomplexes formed in step c. and optionally step d. a. depositing at least one aliquot portion of the biological sample on a deposit area of an electrophoretic gel plate, said sample deposit area being at a position of the gel plate enabling electrophoretic migration of the protein content of the deposited sample towards the anodic side of the gel plate, and b. depositing at least one antibody which is modified to bear additional negative electric charges, said modified antibody having antigenic specificity for a predetermined target immunoglobulin or fragment thereof that may be present in the biological sample and having the capability to form an immunocomplex with said predetermined target immunoglobulin or fragment thereof, wherein the at least one modified antibody is deposited on a deposit area of the electrophoretic gel plate that coincides with the sample deposit area of step a. or is separated from the deposit area of step a., being on the same track but at a position that is more cathodic with respect to the position of the sample deposit area of step a., in particular between the cathodic extremity of the gel plate and the sample deposit area of step a., wherein steps a. and b. can be performed in any order or at the same time when the modified antibody deposit area and the sample deposit area are separated, or, when the modified antibody deposit area and the sample deposit area coincide, the deposit of an antibody according to step b. is carried out before or after the deposit of an aliquot portion of the biological sample according to step a., and c. electrophoresing the gel plate to obtain a protein separation profile of the biological sample deposited in step a., the at least one modified antibody deposited in step b. displacing specifically the predetermined target immunoglobulin or fragment thereof that may be present in the biological sample outside the gamma zone and/or protein profile during the electrophoretic migration, and d. applying at least one capture antibody on appropriate zone(s) of the electrophoresed gel plate, wherein said capture antibody has specificity for a particular antibody isotype, or has specificity for the target immunoglobulin or fragment thereof, or has specificity for a particular antibody isotype and/or target immunoglobulin or fragment thereof as found in an immunocomplex between the target immunoglobulin or fragment thereof and the at least one modified antibody, and permitting its reaction to enable the formation of precipitated and/or detectable immunocomplexes, and e. optionally, staining the immunocomplexes formed in step c. and optionally step d.