Modified solid ion-selective electrode for potentiometric determination of sulfide in oil refineries water

A selective electrode was manufactured to determine the sulfur ions by sedimentation method in industrial waters in oil refineries of North Refineries Company, Baiji, Iraq. The linear response on a wide range of concentration (from 1.0·10–1 to 1.0·10–6M) Na2S with a Nernst response of 28.229 mv per decade, theoretical value for slope of 29.58 mv per decade, correlation factor of 0.9998, detection limit of 2.287·10–7 at 25–35°C, pH 6.0–12.0, and the best concentration of the filling solution of 10–6M with a fast response time (5–13 s). The direct method were %RSD for 0.5772– –0.7430, %RE for –0.1, 3.7 and %REC for 99.9, 103.7.