Idstein, Germany) and an electrochemical detector (TED 4020, Trace, Braunschweig, Germany) with a platinum flow-through electrode.Aswitchvalvewasusedforconsecutiveanalysesofsam-ples in two different ways, allowing either a comparison of two different enzyme reactors or a comparison of measurements with and without enzyme reactor. A schematic view of the setup with two integrated enzyme reactors is presented in Fig. 1.