An inexpensive and renewable pencil electrode for use in field-based stripping voltammetry

Renewable graphite pencil writing devices have been available for many years. In this work it is shown that those writing tools are readily adapted to produce a ''low tech'', renewable and minimal cost electrode which, when employed for anodic stripping voltammetry under mercury plated thin-film conditions, performs equally well as commercially available ''high tech'' carbon electrodes. In the absence of the mercury film, small background currents arising from clays and polymers present in pencil graphite are detected and some ''thin layer'' responses resulting from solution creepage between the graphite and the PTFE holder are observed. However, these problems are absent when an in situ mercury film electrode is prepared. AC and DC voltammetric studies were undertaken on the oxidation of hexacyanoferrate(II) and on the stripping voltammetry of cadmium and lead (ng ml(-1) range) to demonstrate the voltammetric characteristics of the renewable pencil electrode. Stripping voltammetric data are compared with results obtained at a glassy carbon electrode to demonstrate the high quality of performance that can be achieved.