Devices, systems, and methods for conducting chemiluminescent immunoassay testing and, more particularly, to initiating and monitoring a chemiluminescent reaction in a plurality of such assays, of different types, on a single immunoassay instrument, in a single procedure, using a plurality of labels and a triggering reagent combination are disclosed. Moreover, by including a base reagent injector assembly having an “e-channel” to provide a swirling turbulence to the base reagent immediately before it is introduced into the well of a cuvette containing a sample and an acid reagent. The added turbulence addresses the phenomenon referred to as “RLU shift,” in which the luminescence output can increase or decrease between assays.