Abstract: A flow-through sample cell operable in conjunction with a reflectance or fluorescence spectroscopy apparatus to permit real-time analysis of a liquid sample stream is disclosed. The flow-through sample cell includes a housing and a conical-shaped flow control body positioned within the hollow interior of the housing. A liquid sample stream to be analyzed is introduced into the housing along a flow path tangential to the outer surface of the flow control body so as to cause the liquid sample stream to flow through centrifugal action radially along the outer surface of the conical-shaped flow control body and into a viewing area at the bottom of the sample cell. As the liquid sample stream flows through the viewing area, a real-time analysis of the liquid sample stream may be made by an analyzer device positioned outside the sample cell and adjacent to the viewing area.