Electroanalytical studies on Cu (II) ion-selective sensor of coated pyrolytic graphite electrodes based on N_2S_2O_2 and N_2S_2O_3 heterocyclic benzothiazol ligands

摘要

Benzothiazol based chelating ionophores such as 1,3-bis[2-(1,3-benzothiazol-2-yl)-phenoxy]propane (L_1) and 1,2'-bis[2-(1,3-benzothiazol-2-yl)-phenoxy]2-ethoxyethane(L_2) were synthesized and explored as neutral ionophores in the fabrication of Cu~(2+) 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 L_2: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 L_2 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 Cu~(2+) 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 Cu~(2+) with EDTA.