Development of electrochemical method for the determination of Azo Dyes based colorants in food and beverage products

• Main Author: Rovina Kobun
• Format: Thesis
• Language: English; English
• Published: 2018
• Subjects: QD Chemistry
• Online Access: https://eprints.ums.edu.my/id/eprint/22630/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/22630/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/22630/

Development of a rapid and sensitive electrochemical method is important for monitoring synthetic colorants in food and beverage products which caused toxicity and pathogenicity to human health when excessively consumed. Herein, an electrochemical sensor was developed based on the modifications of glassy carbon electrode (GCE) with chitosan (CHIT), graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) for the determination of azo colorants (Amaranth (AM), Allura Red (AR), Sunset Yellow (SY) and Tartrazine (TZ)) in food and beverage products. The hybrid nanomaterials of CHIT/MWCNTs/GO/AuNPs were effectively enhanced electron-transfer and promoted the current response of azo colorants. Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior with the modified GCE in the present of methylene blue as a redox indicator. The morphological characteristics of nanomaterials were observed high porosity, under scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscope (TEM). Potential peak currents were found in the order of bare GCE>CHIT/GO>CHIT/GO/MWCNTs> CHIT/GO/MWCNTs/AuNPs. The modified-GCE showed optimum response when operated at 25 ±1 °C at pH 7 of PBS as working solution (0.1 M) for all tested colorants. Meanwhile, the scan rate was found of 0.35 V s-1 for AM, 0.2 V s-1 for AR, 0.25 V s-1 for SY and 0.3 V s-1 for TZ, within 5,10,30 and 50 sec, respectively. Under optimal conditions, the developed sensor was tested with different concentrations of standard AM, AR, SY and TZ in the ranged of 10 to 90 mg mL71. The limits of detection and quantification ranges were found to be 0.032 to 0.5 mg mL-1 and 0.096 to 0.92 mg mL-1, respectively. Sensitivity value of AM, AR, SY and TZ were calculated to be 0.01,0.02,0.06 and 0.05 pA/mg mL-1 mm3, respectively. The developed sensor was successfully applied to determine AM, AR, SY and TZ in candy, jelly and soft drinks samples, and good recovery values range from 93.19 to 104.03 %. This simple and sensitive sensor offers low cost and rapid detection of specific colorants without skilled operators and sophisticated instruments.