Ni(II)-5, 10, 15, 20-tetrakis(4-carboxyphenyl) porphyrin conjugated onto TiO2 nanospheres for the electrochemical detection of nitrite

In this report , composites of porphyrins and TiO 2 are developed for the detection of nitrite. The porphyrins employed are free base (TCPP) and Ni(II) (NiTCPP) 5, 10,15,20-tetrakis(4-carboxyphenyl) porphyrin. TCPP and NiTCPP were characterized using ultraviolet-visible light spectrophotometry (UV-Vis) which showed the expected bands and the time-of-flight-secondary ionization mass spectrometry which showed acceptable m/z values. Following this, they were conjugated onto TiO 2 nanospheres (TiO 2 NS). The characterization of the nanoconjugates was done using solid state UV-Vis which showed hybrid bands, X-ray diffractometer, Brunauer-Emmett-Teller analyzer, atomic force microscopy, and transmission electron microscopy. An irreversible diffusion-controlled oxidation was observed upon electrochemical sensing of nitrite. TiO 2 NS-NiTCPP showed high sensitivity in terms of limit of detection (LoD) compared to previous reports. The obtained limit of detection was 4.60 μM and lower than the known permitted amount of 1 mg/L for nitrite in drinking water.