Depending on the mercury-to-metal ratio, a liquid, paste or solid amalgam is formed. Solid and paste electrodes are more reliable and more convenient in analytical practice where manipulation with the working electrode is necessary (flow-through systems, mobile laboratories, methods based on accumulation of an analyte in one solution and measurements in another). Paste and solid amalgam working electrodes can be properly modified and/or can contain metals which interact with analyte in a different way than mercury. These characteristics of amalgam electrodes make their electrochemical applicability wider. Amalgam electrodes allow in many cases not only to substitute hanging mercury drop electrode but also offer new approaches which cannot be realized with mercury electrodes.
Optimum conditions are described for the determination of micromolar and submicromolar concentrations of herbicide Biphenox by differential pulse voltammetry (DPV) on non-toxic solid silver amalgam electrode modified with mercury meniscus in aqueous methanolic (9:1) Britton-Robinson buffer (pH 7). The limit of quantification is 2.4·10-7 mol l-1. Cyclic voltammetry with the same working electrode was used to clarify the mechanism of the electrode reaction.
