| abstract |
@ An assay device for determining the presence of analyte (e.g. antigens and/or haptens) in a liquid sample comprising a first (reagent) zone containing reference antigens and labeled Fab fragments which are capable of reacting immunologically with said analyte and said reference antigens, said Fab fragments being positioned in said first zone such that they will be removed therefrom when reacted with analyte passing through said first zone but will not be removed from said first zone in the absence of analyte; and a second (reaction) zone wherein the reaction product of said labeled Fab fragment-analyte passes after removal from said first zone and in which said label or a reaction product thereof emits a detectable signal. The detectable signal emitted in said second zone may, for example, be a color produced by reaction with a chromogenic material in said second zone or it may, for example, be electromagnetic radiation, e. g. chemiluminescence or fluorescence produced by interaction with a reagent in said second zone. |