Magnesium-PVC Membrane Sensor Based on 4,5-Bis(Benzoylthio)-1,3-Dithiole-2-Thione

Abstract

This report describes an attempt to develop potentiometric Mg²⁺ sensors based on a liquid polymeric membrane. Membrane incorporating 4,5-Bis(benzoylthio)-1,3- dithiole-2-thione (Bz₂dmit) as ionophore, with composition Bz₂ dmit:NaTPB:NB:PVC in the ratio 2.5:2.5:65:30 (w/w), exhibits the best result for potentiometric sensing of Mg²⁺ ions. The proposed electrode, based on Bz₂ dmitwith nitrobenzene (NB) as a solvent mediator in a polyvinyl chloride (PVC) membrane matrix, exhibited a near-Nernstian response to Mg²⁺ in the concentration range of 1.0 × 10⁻⁵ to 1.0 × 10⁻¹ M, with a slope of 29.2 mV per decade of activity of Mg²⁺. The lower limit of detection was 1.0 × 10⁻⁵ M. This sensor showed high selectivity with respect to alkaline, alkaline earth, transition, and heavy metal ions, except for Sr²⁺, and could be used over a pH range of 3.5–9.0. It can be used for at least 2 mo without considerable divergence in potentials and has a relatively fast response of <10 s. It was applied successfully as an indicator electrode in potentiometric titration of Mg²⁺ ions with EDTA.

Keywords:

• 4,5-Bis(benzoylthio)-1,3-dithiole-2-thione
• ion-selective electrode
• magnesium
• potentiometry
• PVC membrane
• sensor

The authors gratefully acknowledge the financial support from the Research Council of the Quchan Islamic Azad University and University of Payamenoor for this research.

Notes

NM: Not mentioned.