Carbon-fiber micro-electrodes as substrates for mercury films

Conditions for mercury deposition at a cylindrical carbon-fiber micro-electrode are examined. A better construction of electrode body with a means of holding the fiber is described. Data obtained in thiocyanate and acetate buffer solutions suggest that in order to obtain linear dependence of the square-wave stripping peak on the mercury concentration, the deposit should not exceed a few monolayers. The surface inhomegeneity of the carbon fibers was confirmded by electron microscopy. The codeposition of lead(II) with mercury(II)_is described; the square-wave stripping peak increased linearly with lead concentration up to 4 μM. Cyclic staircase voltammograms showed enhanced response to lead(II) at a mercury-coated fiber.