Fabrication of a silver (I) ion PVC-membrane sensor based on 2-{(E)-[(2-amino-5-nitrophenyl)imino]methyl}-4-methoxy phenol as a selective sensing material

Abstract

The Schiff-base 2-{(E)-[(2-amino-5-nitrophenyl)imino]methyl}-4-methoxy phenol, was synthesised and explored as a suitable ionophore for preparation of poly(vinyl chloride) based membrane sensor selective to silver(I) ion. The addition of potassium tetraphenyl borate and various plasticisers, viz. o-NPOE, DBP, DMS and DOP was found to substantially improve the performance of the sensor. The electrode revealed a Nernstian behaviour over a wide silver ion concentration range (1.0 × 10⁻⁶–1.0 × 10⁻¹ mol L⁻¹) with relatively low detection limit (7.5 × 10⁻⁷ mol L⁻¹). The potentiometric response was independent of the pH of the solution in the range of 1.8–5.0 with very short response time (<5 s). The proposed electrode can be used for at least two months without any considerable divergence in potentials. It exhibits very good selectivity relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions. The selectivity of the proposed sensor shows great improvements compared to the previously reported electrodes for silver ions. The sensor was also found to work satisfactorily in partially non-aqueous media up to 25% (v/v) content of acetone with respect to water and can tolerate the concentration 0.05 (w/v%) of non-ionic (Triton X-100) surfactant. The sensor could therefore be used for Ag⁺ ion estimation in radiographic films occupationally exposed.

Keywords:

• silver-selective electrode
• potentiometric titration
• 2-{(E)-[(2-amino-5-nitrophenyl)imino]methyl}-4-methoxy phenol (ANPIMMP)
• coated-graphite electrode