A new ion-selective electrode for potentiometric determination of Ce(III) ions

A novel ion-selective PVC membrane sensor for cerium(III) ions based on [4-(4′-nitrobenzyl)-1-phenyl-3,5-pyrazolidinedion)] (NBPP) as a new ionophore has been prepared and studied. This electrode has a wide linear dynamic range from 10−1 to 2.5 × 10−6 mol l−1 with a Nernstian slope of 19.5 ± 0.2 mV decade−1 and low detection limit of 1.6 × 10−6 mol l−1. It has a fast response time (<10 s) and good selectivity with respect to different metal ions. NBPP-based electrode was suitable for aqueous solutions of pH range from 4.0 to 8.0. It can be used for about 3 months without any considerable divergence in potential. The formation constant of ionophore complex with Ce(III) was calculated by using segmented sandwich membrane method. The nature of NBPP ionophore and its Ce(III)-complex is examined using Fourier-transform infrared analysis and elemental analysis techniques. The proposed electrode has been used successfully as an indicator electrode in potentiometric titration of phosphate and oxalate in aqueous media and carbonate, fluoride and acetylsalicylate in some drugs.