NITRATE ION-SELECTIVE SENSOR-BASED ON ELECTROCHEMICALLY PREPARED CONDUCTING POLYPYRROLE FILMS

Nitrate-doped polypyrrole (PPy) films on a glassy carbon substrate hav e been prepared electrochemically in aqueous, acetonitrile, and propyl ene carbonate solutions for use as nitrate sensors. Lithium nitrate, s odium nitrate, nitric acid, tetraethylammonium p-toluene sulfonate (TS ), and tetradodecylammonium nitrate (TDN) were employed as electrolyte s. The effect of dibutylphthalate (DBP) as a plasticizer on the sensit ivity and lifetime of PPy film sensors was also investigated. A Nernst ian behavior with a slope of 56.9 mV/decade over 0.1-7.4x 10(-5) M NO3 - and a detection limit of 4.7 x 10(-5) M were observed for the polyme r sensor prepared in acetonitrile solution containing lithium nitrate and 15% plasticizer (DBP). A lifetime of more than 6 months for this P Py film electrode was obtained.