| The use of pesticide in agricultur has greatly improved food production , however, which became a greater and greater threaten to environment and the health of human beings. The food safety has been challenges and public health problem of worldwild with the global integration and internationalization of food trade, which bacame the major disput of foreign trade of agricultural commodities.Conventional methods for detecting residual pesticides were time consuming and costly, and were hard to satisfy the increasing requirements of the online detection. As a comparison, the system of ternaty heteropoly acids provided a promising way to detect organophosphorus pesticides which was rapid,sensitivity and simple. So we placed emphasis on studying on novel fluorescence spectrographic and RLS methods to detect residual pesticides in the paper. Organophosphorus can form heteropoly acid, by which ion-associate complex has been product through the reaction between the negativeion of heteropoly acid and Rodmin B, which causes the change of fluorescence and RLS spectrographic . Base on it novel methods had been study, and some work had been done一Synthesis and characterization of thimet-heteropolytungstic acidThe study provided theory foundation for detecting residual pesticide by the system of ternaty heteropoly acids .In a acid medium, the thimet-heteropolytungstic acid with thimet as the coordinate center were synthesized for the fist time and subsequently characterized by IR and IU. The Keggin type structure was revealed in the complex,which supply a new mentality for the Synthesis of heteropoly acid and Determination of organophosphorus pesticides.二The study on fluorescence quenching method to rapidly Determine organophosphorus pesticides by organophosphorus molybdate heteropoly acids with ternary heteropoly acids Heteropoly acid has been producted in the acidic medium by the reaction between the sodium molybdate and the organophosphorus pesticides, which can form ion-associate complex with Rhodamine B,it causes fluorescence intensity of Rhodamine B to occur quenching. So a novel method to determine organophosphorus pesticides. The optimum conditions of the determination were studied. The calibration curve of organophosphorus pesticides is linear with content of organophosphorus pesticides. (r≥0.9953), and the detected limit is under (3σ)0.0904 nmol/L, and the RSD of the method is under 2.86%. Satisfactory results were obtained accordant with the results obtained through the method of gas chromatography.三Study on quickly determination of thimet residue by resonance light scattering method with with ternary heteropoly acidsA heteropoly acids can been formed through the reaction between thimet and sodium tungstate in an acid medium, and association particle were produced by which combined with Rhodamine B,the experiment indicated that it induce violent increase of RLS atλex/λem = 606nm, A good linear relationship was exhibited in the range of thimet concentration of 0.43-200 nmol/L(r = 0.9977), and the detected limit was down to 0.057 nmol/Lwith recoveries of 82.5.-99.3 %, subsequently the method was applied to determine the concentration of thimet residue in vegetable. Satisfactory results were obtained and accordant with the results obtained through the method of gas chromatography.四Study on the application of ternary heteropoly acids to determine other substance(borax)It is based on the boron molybdenum heteropoly acid has been producted in the acidic medium by the reaction between the ammonium molybdate and the borax, which can form ion-associate complex with Rhodamine B, it causes fluorescence intensity of Rhodamine B to occur quenching, The optimum conditions of the determination were studied. The calibration curve of borax is linear under the range of 2.4~108μg/L atλex/λem = 540nm/582nm.The correlation coefficient is over 0.9982, and the detected limit is 1.42μg/L , the recovery of the addition experiment of the sample is 91.3%~ 101%. And the RSD of the method is under 3.76. It has been used to determine the trace borax in food with satisfactory results.
|
PDF Full Text Request