This invention refers to continuous flow devices for detecting and/or removal of contaminants from a liquid stream. The device comprises a cartridge with an inlet and outlet for the liquid stream, a radiation incident and emerging wall portion and optically transparent support material packed in the cartridge such that a liquid stream can pass between voids or spaces formed within the optically transparent material, as well as a radiation source and detector. The support material comprises molecules for capturing at least one contaminant on the surface of the support material and each of the capture molecules comprises at least one reporter group which emits a signal upon binding of the contaminant. Another form of the invention refers to a rotatable support within the liquid stream.