Abstract: The present invention makes use of a single detector to monitor several process functions, e.g. reaction efficiency, reagent flow rates, the presence of empty reagent reservoirs, the absence of a chemical reactor column in the system, blockage of flow system, etc., at a single location in the flow system. In accordance with the detection scheme of the present invention, only one detector is required to accomplish the same, if not more, functions as many detectors in the prior art instruments. In the described embodiment, an optical detector is positioned downstream of a chemical reaction chamber. This detector monitors the effluent from the reaction chamber to monitor the reaction efficiency. It also monitors the system functions upstream of the reaction chamber. System flow rate is monitored by detecting the presence of a gas bubble which has been introduced into the system at a known instance.