Heavy metal ion detection on a microspot electrode using an optical electrochemical probe

Electrochemical sensors can be used to create portable, attractive, high-sensitivity devices to detect heavy ions in water at a reasonable cost. A novel method of measuring local redox on an electrode using the differential reflectivity measured on an approximately 6 micron diameter spot using a He/Ne laser beam is described. Field focusing and electrode modification enhance the sensitivity, making the method ideal for miniaturization and multiplexing multiple analytes on a monolith electrode. The method is demonstrated by detecting Pb, Hg, and As ions at ppb and ppt levels.