An apparatus and an assembly for processing a sample are provided. The apparatus comprises a plurality of spaced-apart reservoirs, a plurality of channels, and a plurality of outlets, each outlet comprising an effluent discharge opening. The apparatus forms a plurality of flow paths, each flow path comprising a reservoir, a channel, and an outlet. An analyte capture element can be slideably engaged in a channel in a position where it is in fluid communication with the flow path. The apparatus with the analyte capture element disposed in the flow path can be used to process a liquid sample. A method of detecting an analyte in the liquid sample is also provided.