Interference resistant solid state reference electrode

A solid state reference electrode comprising:

• a reference element in ionic communication with a composite, the composite comprising an electrically insulating water-permeable polymeric matrix loaded with a solid inorganic salt comprising a reference anion, wherein the solid inorganic salt is sufficiently soluble in water that hydration of the composite will produce a constant saturation solution concentration of the reference anion at the reference element, and wherein the reference anion is capable of participating in a desired redox half-reaction at the reference element to provide a reference potential;
• an electrode surface for contacting an analyte;
• and
• a solid ion-exchange material located between the electrode surface and the reference element, the solid ion-exchange material comprising one or more non-interfering ions,
• wherein the reference element is electrically insulated from at least a portion of the solid ion-exchange material, and
• wherein the solid ion-exchange material comprises an ion exchange resin or a metal salt, and is configured to immobilize one or more interfering ions, when present in solution of the analyte, by exchange with the one or more non-interfering ions.