Abstract

CUBILLAN, Dalia; NUNEZ, Neida; GONZALEZ, Graciela  and  CAMARGO, Nuris. Optimization of the potentiometric technique with ion selective electrode for evaluating sulfate ion in aqueous samples. Rev. Téc. Ing. Univ. Zulia [online]. 2002, vol.25, n.2, pp.100-107. ISSN 0254-0770.

An optimization of the potentiometric technique using ion selective electrodes for sulfate analysis is discussed. The determination of SO=₄ ion in water column samples (Latitude N 09°51’17", Lengt W 71º31’41") of the Lake Maracaibo was performed following the optimum parameters. Response time 30 s shorter was exhibited when using NaNO₃ as ISA solution compared with conventional NaClO₄ ISA solution. The titrant solution containing Pb(NO₃)₂ does not interfere with the lead ion selective electrode, the optimum titration rate being 0,008 mL/s. Sulfate ion was titrated against standard Pb(NO₃)₂ 4,83x10^-3 mol/L solution using a lead ion selective electrode vs Ag/AgCl reference electrode. Samples of water colected every two m from 1 m to 27 m depth were analyzed, and levels of SO=₄ ion from 171,84 ± 4,26 to 306,72 ± 9,46 mg/L were found. Significative differente values of sulfate vs depth are shown within 95% of probability.

Keywords : Sulfate; ion selective electrode; water column of Lake Maracaibo.