Modification of glassy carbon electrode using nickel-magnetite nanoparticles for development of glucose and suleite chemical sensor in food application

This thesis presented the development of a high sensitive and selective chemical sensor for determination of glucose and sulfite with electrochemical method. The chemical sensor was developed based on modified glassy carbon electrode with magnetite (Fe3O4) and nickel nanoparticles decorated carbon nanotubes (Fe3O4-CNTs-NiNPs). Fe3O4 nanoparticles were in situ loaded on the surface of carboxylated multi-walled carbon nanotubes (CNTs-COOH) by a chemical co-precipitation procedure. Nickel nanoparticles (NiNPs) were prepared through reducing nickel chloride by hydrazine hydrate and then decorated on Fe3O4-CNTs using ultra-sonication Chemical sensor was fabricated using glassy carbon (GC) coated with Fe3O4-CNTs-NiNPs composites film. This developed chemical sensor (Fe3O4-CNTs-NiNPs/GC) was applied to studied the electrochemical oxidation of two parts; (i) electrochemical oxidation of glucose, and (ii) electrochemical oxidation of sulfite. The electrochemical detection was investigate using Ag/AgCl and Pt wire as reference and counter electrode, respectively.
Glucose chemical sensor was developed based on electrochemical oxidation of glucose using amperometry on the modified electrode (Fe3O4-CNTs-NiNPs/GC) in a supporting electrolyte of 0.1 M solution sodium hydroxide (pH 13.0). Results indicated that the Fe3O4-CNTs-NiNPs/GC electrode exhibited excellent performance in the electrochemical oxidation of glucose at an applied potential of +0.55 V (vs. Ag/AgCl). The developed electrode provided a linear dynamic range for glucose from 10 M to 1.8 mM (r2=0.998) with the sensitivity of 335.25 A mM-1; and a low detection limit of 6.7 M(S/N=3). The developed sensor provided good precision (%RSD = 4.18) was estimated from six amperometric measurements of 0.5 mM glucose. In addition, the fabricated sensor was successfully applied to determine glucose in honey and energy drinks with good results.
The development of sulfite chemical sensor using the modified electrode (Fe3O4-CNTs-NiNPs/GC) was also applied for determination of sulfite (SO3 2-). Quantitative analysis of sulfite was studies at the modified electrode using linear sweep voltammetry in 0.1M phosphate buffer pH 7.0 as supporting electrolyte. The oxidation of sulfite was found at +0.38 V. The sulfite oxidation currents varied linearly with the concentration of sulfite from was 0.1-10 mM (r2=0.995) with the sensitivity of 12.748 A.mM-1. The limit of detection was 28 M (S/N = 3). The application of this developed sensor in wine, pickled mustard green and garlic had also been successfully. The storage stability of Fe3O4-CNTs-NiNPs/GC can be stored for up to 3 weeks at room temperature. Furthermore, the development chemical sensor provided a high sensitivity, acceptable selectivity and simples of preparation and low cost.