Long-lived sensors with replaceable surface for stripping voltammetric analysis: part II

• Published in: Analytica chimica acta 2004-07, Vol.516 (1), p.49-60
• Main Authors: Malakhova, N.A, Miroshnikova, E.G, Stojko, N.Yu, Brainina, Kh.Z
• Format: Article
• Language: English
• Subjects: Heavy metals; Modified surface; Stripping voltammetry; Tape electrode
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2004.04.008

The tape electrode, consisting of flexible polymer substrate, covered with carbon-containing paste and modified by calomel, has been developed as an alternative to the flexible voltammetric sensor with replaceable surface, which was made of a carbon-containing filament and modified beforehand by insoluble mercury diethyldithiocarbaminate. The tape electrode was fabricated using commercially available materials and the screen-printing technology. Optimal conditions have been chosen for the electrochemical “activation” of the modifying layer of the calomel. These conditions provided a thin mercury layer comprising microscopic droplets 1–4 μm across on the electrode surface. Main experimental data obtained with the use of developed electrode followed the theoretical laws for the discharge-ionization of metals on the surface of solid and mercury thin-film electrodes. As compared to the carbon-containing filament, the tape electrode considerably extends the number of determinable amalgam-forming metals ions and allows decreasing their detection limits by more than one order of magnitude. The detection limit of 0.12 μg l −1 for copper, 0.02 μg l −1 for lead and cadmium and 0.05 μg l −1 for zinc was achieved after a 2 min accumulation. A high reproducibility of analytical response (0.6–2.3% R.S.D.) was achieved for nine repetitive measurements of 1 μg l −1 of these metals. The response values obtained with the tape sensor were directly proportional to the concentration of the metal ions over a broad concentration interval (0.1 μg l −1 to 0.5 mg l −1) at different accumulation times (120–10 s). Therefore, the newly developed low-toxic sensor can be used in automatic systems for environmental monitoring (at the trace level inclusive), processing solutions and waste waters.