The use of an H3O+ sensitive electrode obtained by recovering a graphite rod with a polymeric membrane containing PbO2 attached in a PVC matrix, as a working electrode in coulometric acid-base titrations is described. The coulometric curves obtained with the proposed electrode were similar to those obtained with the glass electrode and the equivalence times agreeded within a 95% confidence level. The time response of the PbO2-PVC electrode was faster than that of the glass electrode with standard deviations (n=3) of ± 0,01 s. The PbO2-PVC electrode presented a slope of -57,6 mV/pH and linear response from pH 1 to 12 (r=0,9998). The proposed electrode is of easy construction, low cost and a life time of at least 7 months, equivalente to at least 1200 determinations.
lead dioxide; PVC membrane electrode; coulometric titration
