Studies On Novel Chemically Modified Glassy Carbon Electrode And Its Application

Sudan I is a artificial "azo" dye usually used in oil paint,printing,waxes,plastics, and dyeing since its bright and vivid colors could improve the luster of commercial products.However,Sudan I has been found in food products containing hot chili in some parts of the world,which is a crucial risk to human health.There is evidence that Sudan (Ⅰ-Ⅳ)are biologically active through their metabolites and have been associated with increased occurrence of bladder cancer in textile and leather dyers,painters,and hairdressers.Therefore,sudan I has been classified as a category 3 carcinogen by the International Agency for Research on Cancer(IARC).And the use of sudan I in foodstuff is forbidden by a global food regulation act.To date,the standard used to detect the Sudan family is based on a liquid chromatographic method approved by the European Commission,and other approaches such as HPLC/APCI-MS,and HPLC-DAD detection have also been made.Whichever method is used,separation with HPLC is needed first,which is time-consuming and brings about inconvenience to analysis in real time.It is well known that electrochemical method is simple and inexpensive as an analytical technique.In this paper,bismuth-film electrodes(BiFEs)and multiwalled carbon nanotube modified glass,carbon electrode(MWCNT/GCE)have been used respectively,to electrochemical detection of Sudan I.The details are listed below:First,BiFE was prepared by ex situ depositing bismuth onto GCE for the detection of Sudan I.The sufficiently wide negative potential window available made the BiFE a potentially suitable electrode for application in the field of cathodic electrochemical detection of Sudan I.The BiFE showed similar or even favorable behavior compared to that of mercury and bare electrode.Operational parameters,including the deposition potential and time of bismuth-film,pH of the analytic solution and co-solvents have been optimized.Under the optimum experimental conditions,the cathodic voltammetrie response was proportional to the concentration of Sudan I range from 1.0×10^-7to 1.6×10^-5mol/L,with a correlation coefficient of 0.9987.The detection limit was 3.3×10^-8 mol/L based on signal-to-noise ratio equal to 3.Due to the easy preparation and regeneration of BiFE together with its good reproducibility and stability,the combination of the promising BiFE and cathodic voltammetric performances opens new opportunities for fast,simple,and sensitive analysis of Sudan I in samples. Second,MWCNT was developed as a new sorbent for solid-phase extraction(SPE) of Sudan I.A combination of SPE with square-wave voltammetric(SWV)analysis resulted in a fast,sensitive,and selective electrochemical method for the determination of Sudan I.Because of the strong affinity of MWCNT for(polynuclear)aromatic compounds,Sudan I can strongly bind to the MWCNT surface.The macroporosity and heterogeneity of MWCNT allow extracting a large amount of Sudan I in 2 min.The stripping response was highly linear over the Sudan I range of 8×10^-7-1.28×10^-5mol/L, with a detection limit of 2.67×10^-7mol/L.The determination of Sudan I in ketchup samples showed acceptable accuracy.The fast extraction ability of MWCNT makes it promising sorbent for various solid-phase extractions.