Abstract: An electrochemical cell includes a measuring electrode and a reference electrode. The reference electrode includes a flowing liquid junction between a reference fill fluid and a sample. The flowing liquid junction is configured to inhibit particles from blocking or obstructing it. In one aspect a particle filter is provided before the flowing liquid junction to prevent particles from the fill fluid from entering the flowing liquid junction. In another aspect a particle filter is provided after the flowing liquid junction to prevent particles in the sample from entering the flowing liquid junction. In another aspect the flowing liquid junction has a diameter that generally increases from an aperture proximate the fill fluid to an aperture proximate the sample. On example of such a configuration is a tapered flowing liquid junction.