A flow through cell for non-invasive monitoring of fluids flowing therethrough includes a membrane covered view window through which sensors may monitor the fluids. The membranes are secured in position by a frame and retainer assembly with the frame and retainer clamping the membranes in place between the frame support structure and the retainer. The frame is snugly fitted into the cell and includes a sensor receptive chamber for positioning the sensors in the window and in position with the membranes.
