Full Paper Renewable Ceramic (TiN) Ring Electrode in Stripping Voltammetry. Determination of Pb(II) Without Removal of Oxygen B. Bas ´,* R. Piech, M. Ziemnicka, W. Reczyn ´ski, M. Robo ´tka Faculty of Materials Science and Ceramics, AGH University of Science and Technology al. Mickiewicza 30, 30-059 Krako ´w, Poland *e-mail: bas@agh.edu.pl Received: January 27, 2008 Accepted: April 17, 2009 Abstract Characteristic features of the process of Pb(II) reduction and oxidation at a renewable ceramic ring electrode (RCRE) were studied by stripping voltammetry. The main constituents of the RCRE are: a specially constructed TiN ring electrode, a silver sheet used as silver counter/quasi-reference electrode and a silicon O-ring are fastened together in a polypropylene body. The renovation of this electrode is carried out through mechanical removal of solid contaminants and electrochemical activation in the electrolyte which fills the RCRE body. The optimal measurement conditions, composition of supporting electrolyte and procedures of the electrode activation were selected. The measurements were carried out from nondeaerated solutions. As shown on selected examples, RCRE exhibits good performance in underpotential deposition stripping voltammetry (UPD-SV) applied for the determination of lead(II) in synthetic solutions with and without surfactants and in certified reference materials. The peak current is proportional to the concentration of lead(II) over the range 2  10 9 –1  10 7 mol L 1 , with a 3s detection limit of 1  10 9 mol L 1 with an accumulation time of 30 s. The obtained results showed good reproducibility, (RSD ¼ 2 – 5%; n ¼ 5) and reliability. Keywords: Ceramic electrodes, Titanium nitride, Underpotential deposition, Stripping voltammetry, Lead, Redox chemistry DOI: 10.1002/elan.200804598 1. Introduction Electrochemical stripping techniques still attract consider- able attention for both trace metal analysis and for measur- ing several important organic compounds. This is due to the unique preconcentration of analytes on the electrode sur- face and associate favorable low limits of detection. Mercury is considered as the best electrode material, however, the toxicity of mercury and mercury salts used to generate mercury film electrodes (MFEs) limits the usage of these electrodes in analytical practice and makes them unsuitable for out-of-laboratory applications. Therefore, recent effort has been concentrated on development of nontoxic electrode materials that are environmentally friendly. The electrodes made of metals other than mercury are characterized by unsatisfactory repeatability and repro- ducibility and very short periods of parameters stability. Recommended methods of their mechanical and chemical polishing and electrochemical activation are time-consum- ing and usually do not ensure satisfactory reproducibility of the electrode surface and properties [1 – 6]. Similar prob- lems are encountered with solid amalgam [7, 8] and metal composite electrodes [9 – 12] and the electrodes made of carbon derived materials (pyrographite, impregnated graphite, glassy carbon or carbon-containing paste) [13, 14]. In recent years, also fullerenes, nanotubes, nanocrystal- line and boron-doped diamonds [15 – 20] molecularly im- printed polymers [21], conducting polymers [22 – 25], in- organic materials (clays, zeolites, glasses with controlled porosity [26, 27], and inorganic polymers obtained by sol-gel technology [27 – 29] were studied intensively for their application in electrochemical analysis. The new group of materials, that might be considered for electrode construction are metal carbides and nitrides. As has been previously shown a particularly interesting materi- al due to its specific properties is titanium carbide (TiC). The TiC disk electrode was tested for determination of Pb(II) traces [30]. In this work, titanium nitride (TiN) is used for construction of an electrode and when compared to TiC offers better chemical stability and higher corrosion resist- ance [31]. Additionally, TiN obtained by self-propagating high temperature synthesis (SHS) incorporates fewer con- taminants and is more homogeneous and less porous than TiC [32]. The chemical stability and electrochemical corro- sion of TiN in acid and salt solution were many times examined [33 – 35]. Electrical double-layer characteristics and hydrogen evolution reaction (HER) at thin film and bulk TiC and TiN electrodes were described previously [36, 37]. There is no information about application of TiN in voltammetry. In this work, an early study of the renewable TiN-ceramic ring electrode (RCRE), as a suitable alternative (mercury – free) sensor for trace metal analysis, is presented. The possibilities of renovation of the solid electrodes in the 1773 # 2009 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim Electroanalysis 2009, 21, No. 16, 1773 – 1780