Cobalt phthalocyanine derivatives as neutral carriers for nitrite-sensitive poly(vinyl chloride) membrane electrodes

PVC membrane electrodes based on cobalt phthalocyanine and its derivatives are described. An electrode that exhibits the selectivity sequence NO2– > SCN–≈ I–≫ CIO4– > Br– > NO3– > Cl– > OAc– was prepared. The electrodes show a linear response towards nitrite in the range 6 × 10–2–5 × 10–6 mol dm–3 with a slope of –52.0 mV decade–1(at 20 °C). The electrode has a satisfactory reproducibility and a rapid potential response. The UV spectra of the carrier and the a.c. impedance of the membrane were studied.