A novel paste electrode based on a silver solid amalgam and an organic pasting liquid

The silver solid amalgam fine powder mixed with a proper pasting liquid, firstly introduced in this work, was found to be a new suitable electrode material for sensitive voltammetric determination of electro-chemically reducible organic compounds. The optimal composition of the amalgam (mercury/silver ratio) and the formed paste (i.e., quality and quantity of pasting liquid and its ratio relative to amalgam) was tested by modern voltammetric methods using 4-nitrophenol as a model compound. This new non-toxic electrode material combines the advantages of an easily renewable paste electrode surface solving the problems connected with the passivation of the solid electrodes and of amalgam electrodes providing good mechanical stability, simple handling and preparation, wide potential window in cathodic potential range and sufficient sensitivity. The silver amalgam fine powder prepared in the weight ratio 60/40 (Hg/Ag) mixed with paraffin oil in the weight ratio 20:1 (w/w) was found to be the most convenient for the determination of 4-nitrophenol using differential pulse voltammetry with limit of detection 1 mu mol l(-1) in 0.2 mol l(-1) acetate buffer pH 4.8. (C) 2010 Elsevier B.V. All rights reserved.