Stable Amperometric Sensor Based on Novel Polymeric Zinc Phthalocyanine Film for the Nanomolar Detection of Ammonia

Novel zinc tetra [4-[2-(1H-benzimidazol-2-yl) phenoxy]] phthalocyanine (ZnTBImPc) was prepared in a pure state and good yield. The characterization of the ligands and complex were done by combination of techniques like elemental analysis, UV-Visible, FT-IR, Mass, TGA, XRD and electrochemical techniques. The benzimidazole moiety of ZnTBImPc undergoes electropolymerization and the polymeric layer deposits on glassy carbon surface. The polymeric film interface was characterized and used for the voltammetric sensing of ammonia which showed linear characteristics in 0.1 to 1.0 µM range. The LOD was 0.03 µM with sensitivity of 237.25 µAµM-1cm-2. The efficiency and sensitivity of ammonia oxidation at the poly(ZnTBImPc) was compared with the composite hybrid electrode of poly(ZnTBImPc) and carbon nanoparticle (CNP). The amperometric sensing of ammonia showed linear behaviour in the 0.05 to 0.5 µM range. The RDE experiment revealed that the number of electrons involved in the ammonia oxidation is nearly 3. The polymeric electrode was subjected to the interference studies to evaluate the selectivity of the fabricated electrode and found that the co-existing molecules did not show interference during the detection of ammonia.