IMMUNOCHROMATOGRAPHIC ASSAY FOR QUANTITATION OF MILK PROGESTERONE

We describe a rapid immunochromatographic method for the quantitation of progesterone in bovine milk. The method is based on a 'competitive' assay format using the monoclonal antibody to progesterone and a prog esterone-protein conjugate labelled with colloidal gold particles. The monoclonal antibody to proges terone is immobilized as a narrow detec tion zone on a porous membrane. The sample is mixed with colloidal gol d particles coated with progesterone-protein conjugate, and the mixtur e is allowed to migrate past the detection zone. Migration is facilita ted by capillary forces. The amount of labelled progesterone-protein c onjugate bound to the detection zone, as detected by photometric scann ing, is inversely proportional to the amount of progesterone present i n the sample. Analysis is complete in less that 10 min. The method has a practical detection limit of 5 ng of progesterone per mi of bovine milk.