ELECTROSTATICALLY ASSEMBLED FILMS FOR IMPROVING THE PROPERTIES OF TETRARUTHENATED PORPHYRIN MODIFIED ELECTRODES

Modified electrodes, suitable for use in flow injection analysis, have been obtained by the electrostatic assembly of films constituted by t wo different porphyrins, namely, III)tetrakis[bis(bypyridine)(chloro)r uthenium(II)] and so-tetra(4-sulpho-natephenyl)porphyrinatezinc(II), f orming alternating layers onto glassy carbon surfaces. The films are s trongly adherent and highly stable, and can be used for at least a wee k without loss of sensitivity. In addition, they exhibit an enhanced a mperometric response and good protection against fouling, e.g., by phe nol oxidation products. Their usefulness in flow injection analysis of nitrite and sulfite ion have been demonstrated. Excellent signal to n oise ratios have been obtained for sulfite down to 10(-6) mol dm(-3), and for nitrite down to 10(-7) mol dm(-3).