An optochemical sensor for Cd(II) and Hg(II) based on a porphyrin immobilized on Nafion® membranes

✍ Scribed by A. Morales-Bahnik; R. Czolk; J. Reichert; H.J. Ache

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 259 KB
• Volume: 13
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/0925-4005(93)85417-9

✦ Synopsis

An optochemical sensor for the detection of Cd(H) and Hg(II) ions in aqueous solutions can be constructed by immobilizing 5,30,15,20-tetra(4-N-methylpyridyl)porphyrin electrostatically onto thin layers (2-3 brn) of Nafion', a strongly acidic cation-exchanger. The developed procedure for sensor preparation results in sensitive layers with an excellent chemical and mechanical stability. Since the Nafion* membrane quantitatively extracts cations from the solution, the kinetics of the increasing absorption of complexes have been measured. For a measuring time of 20 min the detection limits are 5 x lo-' molil (6 CLgn) and 2X lo-' molil (40 pgl) for Cd(I1) and Hg(II), respectively. After each run the sensors can be regenerated. They show no loss in their sensitivity over a period of four weeks.