The main purpose of the present work is to check whether the immunoreactivity of IgG molecules, chemically bound or adsorbed on latex, shows alteration after 6 months of storage, For this purpose, agglutination tests of sensitized carboxylated beads, measuring the immunoreactivity by turbidimetric monitoring after 5 min of immunoaggregation reaction with human C-reactive protein in a stopped-flow spectrophotometer, were repeated, The results show that while the covalently bound IgG maintains and in some cases improves on its previous immunological response, the passively adsorbed IgG shows loss of activity due to a decreased amount of adsorbed protein.