1. A process for preparing the purified conjugate kletochnosvyazyvayuschego agent, a cytotoxic agent, comprising contacting a mixture comprising kletochnosvyazyvayuschego agent conjugate with a cytotoxic agent and one or more contaminants from the ion exchange chromatography to remove the membrane from a mixture of at least a portion of the impurities to obtain thereby purified conjugate kletochnosvyazyvayuschego agentom.2 cytotoxic agent. The method of claim. 1, characterized in that the method successively repeated two, three or four raza.3. . A method according to claim 1, characterized in that the method comprises the steps of: (a) bringing into contact kletochnosvyazyvayuschego agent to a cytotoxic agent to obtain a first mixture comprising kletochnosvyazyvayuschy agent and a cytotoxic agent, and then contacting the first mixture with a bifunctional crosslinking reagent containing linker in a solution having a pH of from about 4 to about 9 to obtain a second mixture comprising kletochnosvyazyvayuschego agent conjugate with a cytotoxic agent which comprises kletochnosvyazyvayuschy agent chemically linked alternation s linker to a cytotoxic agent, and one or more impurities (b) bringing the second mixture in contact with the ion exchange membrane chromatography for removing from a mixture of at least a portion of the impurities to obtain thereby a purified second mixture kletochnosvyazyvayuschego agent conjugate with a cytotoxic agent and (c) treating the purified second mixture after step (b), using the methods of tangential flow filtration, selective precipitation, neadsorbtsionnoy chromatography, adsorptive filtration, adsorption chromatography, or combinations thereof, for
