Abstract: A separation method, a method for detection, a sensor, and a test-kit find application in immunological detection. The separation method provides for separation of a primary species which separation method is suitable for use in an immunoassay method for the detection of an analyte species and includes the use of a first auxiliary species capable of being formed into a second auxiliary species which second auxiliary species is capable of interacting with a third species to facilitate separation.

Abstract: The invention relates to a method of detection, a sensor and a test-kit which find application in immunological detection (e.g., immunoassay). The invention provides, inter alia, a method of detection, suitable for use in immunological detection of an entity, which method includes the use of a secondary species (as defined in the specification), the use of a first detectable species, and the use of a second detectable species. The method may include, for example, the use of a primary species, a secondary species, a first detectable species and a second detectable species. The primary species may be, for example, an antibody or a ligand. The secondary species may be, for example, an auxiliary species such as an auxiliary binder or an auxiliary ligand, or a species which has a part which is an auxiliary function. The entity to be detected may be an analyte species as such or may be an entity which carries or includes analytes species.