Synthesis of polyaniline hybrid composite: A new and efficient sensor for the detection of total volatile basic nitrogen molecules

• Synthesized the polyaniline–curcumin–copper–cobalt hybrid composite as fish freshness sensor.
• Excellent linear relationship exhibited in electrochemical impedance, cyclic voltammetry and visual methods.
• The composite was found to be a potential molecule for the detection of TVBN for fish freshness.

The detection of fish spoilage and adulteration is a challenging problem faced by consumers and traders. A new polyaniline–curcumin–copper–cobalt hybrid composite was synthesized and evaluated for its ability to detect the total volatile basic nitrogen (TVBN) content. The molecule was characterized by spectroscopic, chemical, Fourier transform infrared (FTIR) and atomic force microscope (AFM) methods. The molecule exhibited excellent sensor responses to ammonia and mono-, di-, and trimethyl amines when assessed through visual, spectroscopic and electrochemical methods. The cyclic voltammetric and electrochemical impedance response of the composite to TVBN showed an excellent linear relationship of concentration vs. current and concentration vs. real/imaginary impedance. Dimethyl amine exhibited an unusual cyclic voltammetric response behavior with the current decreasing with increasing concentration. The individual TVBN content can be distinguished by using the electrochemical impedance spectroscopy technique based on the intensity of impedance response. The composite showed distinct color variation with increasing concentration of TVBN from 1 to 200 μg g−1 and the finding was supported by the spectrophotometric response. The spatial sp3 π electron cloud from the organic part and partially filled d orbital electron from the metals played an important role in a more rapid sensing response to the polyaniline hybrid composite. The molecule can be a potential candidate for developing strip sensors, electronic devices, quantitative analytical reagent and TVBN odour absorbers.

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