A diagnostic reagent application based on carbon nanoparticles covalently functionalized by streptococcus G-protein was investigated in order to construct a system for the monitoring and optimization of the affinity purification technology of rabbit polyclonal antibodies to alpha-fetoprotein. The developed system allows semiquantitative assessment ofthe immunoglobulin content (IgG) of most higher animals and human beings in blood serum samples and eluate in a short time (45 min). IgG detection sensitivity using the carbon-G-protein diagnosticum was 80 ng/mL. Approaches to stabilizing the components of the analysis system, which ensures the preservation of their functional properties during long storage, were developed. The storage life of the diagnosticum was more than 20 years, and that of immunosorbents was more than year and a half. A technique of long-term immunosorbent storage, used in the analysis, was developed. Application of the test-system is possible without the presence of registration equipment.