A diagnostic reagent based on carbon nanoparticles covalently functionalized with streptococcus G protein was applied to construct a system for monitoring and optimization of the technology of affinity purification of rabbit polyclonal antibodies to alpha-fetoprotein. The developed system allows a short-time (45 min) semiquantitative assessment of the immunoglobulins (IgG) of most higher animals and human beings in blood serum samples and eluate. 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 was developed. Application of the developed test-system do not require registration equipment.