To rinse the cell and/or load fresh electrolyte for further electrochemical interrogation of the GDE sample, the electrolyte manifold port is connected to waste and ca. 2.1 mL of electrolyte is pumped through the electrolyte pumping port, which flushes the WE fixture. When interrogation of the loaded sample is completed, the above air-pumping procedure is performed to extract all remaining liquid from the working electrode fixture, effectively preparing the working electrode chamber for exchange with a new GDE sample.