In certain electrolytes, modification of the Pt surface is important for its stability. Anodised, nonporous Pt has demonstrated its usefulness as a solid-state reference electrode by virtue of its near-Nernstian behaviour, low hysteresis and rapid response (15). Modifications to Pt wire may extend its usefulness to more electrochemical systems. The use of polypyrrole (16), poly-1,3-phenylendiamine (15) or polyvinyl ferrocene (17) as a surface modifier can successfully suppress significant interference by any coupled redox systems or contaminants. The fact that a Pt electrode can be modified with nitrogen-based polymers or be incorporated as part of a biosensor assembly (18) indicates its resistance to interference from these compounds.