Nanomolar detection of rutin based on adsorptive stripping analysis at single-sided heated graphite cylindrical electrodes with direct current heating

A single-sided heated graphite cylindrical electrode (ss-HGCE) was designed. Compared to previous alternative current (AC) heating, much simpler and cheaper direct current (DC) heating supplier was adopted for the first time to perform adsorptive accumulation of rutin at ss-HGCE at elevated electrode temperature. This offers great promise for low cost, miniaturization and high compatibility with portability. The square wave voltammetry (SWV) stripping peak current was enhanced with increasing the electrode temperature only during preconcentration step. This enhancement was contributed to the forced thermal convection induced by heating the electrode rather than the bulk solution, which is able to improve mass transfer and facilitate adsorption hence enhance stripping response. A detection limit of 1.0 × 10⁻⁹ M (S/N = 3) could be obtained at an electrode temperature of 48 °C during 5 min accumulation, one magnitude lower than that at 28 °C (room temperature). This is the lowest value at carbon-based electrodes for rutin determination as we know. Such novel method was also successfully used to determine rutin in pharmaceutical tablets.