Ion-Selective Electrode for Anionic Surfactants Using Hexadecyl Trimethyl Ammonium Bromide-Sodium Dodecylsulfate as an Active Ionophore

Abstract

The construction and characteristic performance of PVC membrane electrode responsive to sodium dodecylsulfate (SDS) are described in this paper. The electrode is based on hexadecyl trimethyl ammonium bromide-Sodium dodecylsulfate (CTA+DS−) ion pair as ionophore in PVC membrane, which displays a Nernstian slope of −58 ± 0.9 mV/decade in a 5.0 × 10−6 to 2.5 × 10−3 mol L−1 concentration range and a limit of detection of 2.9 × 10−6 mol L−1. The electrode can be used for 3 months without showing significant changes in the value of slope or working range. Also the electrode has wide pH range of application and short response time. The electrode shows a selective response to SDS and a poor response to common inorganic anions. The selective sequence found was SDS > HCO3 − > CH3COO− > Cl− > I− > NO3 −≈ Br− > F− > CO3 2− > C6H5O7 3− > C2O4 2− > SO4 2− > C4H4O6 2− > SO3 2− > PO4 3−. The potentiometric selectivity coefficients determined are indicating that common anions would not interfere in the SDS determination. The electrode has been utilized as an end point indicator electrode for potentiometric titration involving hyamine as titrant.