Electroanalytical studies on Cu (II) ion-selective sensor of coated pyrolytic graphite electrodes based on N2S2O2 and N2S2O3 heterocyclic benzothiazol ligands

Benzothiazol based chelating ionophores such as 1,3-bis[2-(1,3-benzothiazol-2-yl)-phenoxy]propane (L1) and 1,2′-bis[2-(1,3-benzothiazol-2-yl)-phenoxy]2-ethoxyethane(L2) were synthesized and explored as neutral ionophores in the fabrication of Cu2 + ion-selective electrodes. Variety of PVC-based electrodes i.e., polymeric membrane electrodes (PME), coated graphite electrodes (CGE) and coated pyrolytic graphite electrodes (CPGE) were prepared. The membranes having composition L1:PVC:1-CN:NaTPB ≡ 5:38:55:2 (w/w; mg) and L2:PVC:1-CN:NaTPB in the ratio of 6:39:53:2 are found to be exhibit the best potentiometric characteristics. The comparative studies of PME, CGE and CPGE based on L2 reveals that the CPGE is superior in terms of low detection limit of 6.30 × 10− 9 mol L− 1 with a Nernstian slope of 29.5 mV decade− 1 of activity between pH 2.0 to 8.5 with a fast response time of 9 s and could be used over a period of 5 months without any significant divergence in its potentiometric characteristics. The sensor has been employed for the estimation of Cu2 + ion in real samples viz., water, soil and herbal medicinal plants and besides this, the sensor was also used as an indicator electrode in the potentiometric determination of Cu2 + with EDTA.