Study On The Eelectrochemical Analytial Methods Of Food Additive Ingredient

Food is the material foundation for human survival and development,in recent years, with the development of food industry, more and more attention was attracted to food safety problems. Therefore, seeking a kind of rapid, accurate and sensitive analysis method for food quality detection has become the urgent needs of the market. Electrochemical analytial methods, as the most important tool in analycial chemistry fields, exhibit unique superiority of high sensitivity, excellent selectivity, fast response and low-cost instrumentation. At present, electrochemical analytial methods have been widely used in the field of food analysis. In view of this research background, various voltammetric sensor mainly based on electrochemical analytial methods combined with modified electrode were fabricated, which were used for sensitive and fast determination of three food additive ingredient, such as trace element, artificial sweetener and food preservative. The main research are expressed as follows:1. The present approach establishes a highly sensitive and simple voltammetric method for direct determination of trace amounts of iodide based on glassy carbon electrode. In the presence of abounding bromide and appropriate amount of ionic associating agent(cetylpyridine bromide), the iodine can be accumulated on the glassy carbon electrode surface as ionic associate of CPBI2 Br. After accumulation for a period of time, a linear sweep potential with negative going was applied and the I2 in CPBI2 Br was reduced again into solution. Under the optimization conditions, the stripping peak current were linear relationship with iodide concentration in range of 3.81ng/m L to 0.114 μg/m L and 0.127 μg/m L to 2.54 μg/m L, with a detection limit of 1.016 ng/m L(S/N=3) for a accumulation time of 180 s. Determination of trace iodine in pharmaceutical sample, kelp and table salt were performed with high accuracy and satisfactory recovery results.2. A sensitive voltammetric sensor, based on single-walled carbon nanotubes(SWNTs) modifid glassy carbon electrode, was established and used for determination of neohesperidin dihydrochalcone(NHDC). The electrochemical character of NHDC on this sensor was studied by cyclic voltammetry and a reasonable mechanism was also proposed for the first time. The results showed that the proposed modified electrode exhibited excellent redox activity towards NHDC, and a new voltammetric analytical method for NHDC was proposed with a wide liner range from 5×10-8 mol/L to 8×10-6 mol/L and a low detection limit of 2×10-8 mol/L. Finally, the developed method was successfully applied to quantitative determination of NHDC in beverages with high accuracy and satisfactory recovery results.3. A novel voltammetric sensor, based on single-walled carbon nanotubes(SWNTs) composite poly(L-serine) film modified electrode, was fabricated by simple dipping-drying and electrodeposited methods and used for high-sensitive determination of natamycin. At this sensor, the electrochemical response of natamycin was improved greatly due to the synergistic effect of SWNTs and poly(L-serine). Under the optimized condition,a new and sensitive voltammetric method for determination of natamycin was proposed with detection linear range of 6×10-8 mol L-1 ~ 6×10-6 mol L-1 and detection limit of 4×10-8 mol L-1,Meanwhile, the electrode reaction of natamycin was investigated in detail and some dynamics parameters were calculated for the first time. Using the present method, the residual quantity of natamycin in available claret and beverage samples was evaluated with good satisfactory.