CONDUCTIVE POLYMERIC TETRAKIS(3-METHOXY-4-HYDROXYPHENYL)PORPHYRIN FILM ELECTRODE FOR TRACE DETERMINATION OF NICKEL

Stable polymer film electrodes were formed from tetrakis(3-methoxy-4-hydroxyphenyl)porphyrin with NI(II) as the central metal. The nickel-porphyrin polymer films efficiently demetalated in acidic media at pH 1. The resulting demetalated porphyrin polymer electrodes required no preconditioning treatment before exhibiting strong affinity for Ni(II). Electrodes were placed in sample solution to preconcentrate Ni(II) and transferred to a blank electrolysis solution where the signal due to the Ni(II)/NI(111) oxidation In the film was observed by differential pulse voltammetry. A detection limit of 8 ✕ 10‒8 M was obtained for a 60-s exposure to the sample solution. Accurate quantitation of Ni in certified standard reference material NBS 1643 B (Trace Elements in Water) was achieved with the electrode developed. Electrodes with polymeric porphyrin, which can be used as amperometric sensors, were easily and controllably formed and stable with both time and use. The demetalated film could be regenerated with exposure to acid and reused for chemical preconcentration. In interference studies, a 10-fold excess of Co resulted In partial suppression of the Ni(II) signal, but no new signals were observed. Similar concentrations of cations of Zn, Cd, Pb, Cu and Fe did not appreciably influence the Ni(II) response. © 1990, American Chemical Society. All rights reserved.