DEVELOPMENT OF A PARTICLE CONCENTRATION FLUORESCENCE IMMUNOASSAY FOR THE QUANTITATIVE-DETERMINATION OF IGG IN BOVINE-MILK

A rapid solid-phase particle concentration fluorescence immunoassay (P CFIA) was developed to quantitate the total IgG concentration in bovin e milk. The assay is based on agglutination of antibody covalently bou nd to carboxyl-polystyrene particles with the antigen, which is in tur n detected by a fluorescent labeled antibody by epifluorometry. Optimu m assay performance was obtained using 0.25% w/v dilution of 0.8 mum c arboxyl-polystyrene particles coated with 250 mug/mL of rabbit anti-bo vine IgG at pH 4.5, two-step incubation of 30 and 20 min, respectively , and a 1:1000 dilution of the fluorescein isothiocyanate (FITC)-label ed rabbit anti-bovine IgG as the fluorescence signal. PCFIA is simple to perform, sensitive (5 ng of IgG/mL), accurate, repeatable, and fast er than most immunoassays.