Comparative Electroanalytical Study on Fabrication of CN Selective Sensor Based on Polymeric Membrane Electrode and Coated Graphite Electrode

Abstract

The construction and general performance characteristics of PVC-based cyanide selective polymeric membrane electrode (PME) and coated graphite electrode (CGE) incorporating the synthesized 2,4-di-tert-butyl-6-((2(2,4-dinitrophenyl)hydrazono)methyl)phenol (I) is described here. Effect of various plasticizers (o-nitrophenyloctyl ether, oleic acid, dibutylsebacate, dibutylphthalate, tri-n-butylphosphate) and cation excluder, Cetryltrimethylammoniumbromide (CTAB) was studied by constructing membranes having different compositions. The best performance was observed for the membrane having composition of I: PVC: oNPOE: CTAB ratio of 3.5: 36: 58: 2.5 (w/w; mg). So the coated graphite electrode (CGE) using same composition was also constructed and the sensor displays significantly improved selectivity towards CN‾ion. The response features of PME based on the above stated membrane composition was also compared with CGE. The electrode exhibits Nernstian slope for CN‾ions over wide concentration ranges i.e. 8.3 × 10-6 to 1.0 × 10-1 mol L-1 (with PME) and 5.87×10-7 – 1.0×10-1 mol L-1 (with CGE) and response time of 13 s and 10 s for PME and CGE respectively. CGE exhibits low detection limit 3.6×10-8 mol L-1 with Nernstian slope -58.8 ± 0.2 mV decade-1. Furthermore, the electrode shows constant potentials in the pH range of 6-8 and can be used for about 3 months without any significant deviation in their potential response. The selectivity of the sensor is fairly good over most common anions. The extraordinary selectivity of CGE for CN‾ion permits its practice in the determination of CN‾ion in water and edible samples. Practice of the sensor for potentiometric detection of microgram measures of CN‾ion displays an average regaining of 99.5% and a mean standard deviation of 0.5% and the results attained are comparable with those delivered by AAS analysis.