Analytical Sciences

Design of a New DodecylSulfate-Selective Electrode Based on Conductive Polyaniline

Mir FazlollahMOUSAVI,*  Mojtaba SHAMSIPUR,** SiavashRIAHI,* and Mohammad Safy RAHMANIFAR*

*Department of Chemistry, TarbiatModarres University, P. O. Box 14115-111, Tehran, Islamic Republic ofIran
**Department of Chemistry, Razi University, Kermanshah, IslamicRepublic of Iran

A new, simple, sensitive, low cost and rapidpotentiometric method for direct determination of ultra trace amounts ofsodium dodecyl sulfate (SDS) with a new DS^--selective electrodeis reported. The electrode was prepared by electropolymerization ofaniline in acidified DS^- ion on the surface of a Pt electrode.The cyclic voltammetry (CV) was used for electropolymerization ofpolyaniline (PA) in the potential range of -200 to +1000 mV vs.Ag/AgCl. This sensor showed a Nernstian behavior (59.0 ± 2.3mV/decade) over a very wide linear range (1.0 x 10^-9 - 3.0 x10^-6 M) with a detection limit of 1.0 x 10^-9 M. Theresponse time of the electrode was 15 s for 1.0 x 10^-7 M ofanalyte; the electrode can be used for 4 weeks without any major deviation.This electrode can be used in the pH range of 3.5 - 9.8. The selectivityof electrode to DS^- over some organic, inorganic and anionicsurfactants was investigated with the fixed primary ion method. Theresults show that the electrode is highly selective to DS^- ionover other ions. The proposed electrode was applied to the determinationof DS^- in real samples.

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