Affinity immunosensor for milk progesterone: identification of critical parameters

The effects of several experimental parameters on the performance characteristics of a competitive-type immunochromatographic assay of milk progesterone were studied. Increasing the size of the colloidal gold particles used as a label increased both maximal signal obtained and sensitivity of the assay measured as slope of the progesterone standard curve. The concentration of the antibody used to prepare the detection zone was found to be critical factor, in that low concentrations of antibody resulted in a poor sensitivity. The compatibilities of various buffer systems with the assay were studied. The assay worked well with buffers having a broad pH range of 4.5-8.5.