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 electrod e which, when employed for anodic stripping voltammetry under mercury plated thin-film conditions, performs equally well as commercially ava ilable ''high tech'' carbon electrodes. In the absence of the mercury film, small background currents arising from clays and polymers presen t in pencil graphite are detected and some ''thin layer'' responses re sulting from solution creepage between the graphite and the PTFE holde r are observed. However, these problems are absent when an in situ mer cury film electrode is prepared. AC and DC voltammetric studies were u ndertaken on the oxidation of hexacyanoferrate(II) and on the strippin g voltammetry of cadmium and lead (ng ml(-1) range) to demonstrate the voltammetric characteristics of the renewable pencil electrode. Strip ping voltammetric data are compared with results obtained at a glassy carbon electrode to demonstrate the high quality of performance that c an be achieved.