| With the development of economy,people pay more and more attention to their own quality of life. Bear the brunt of the food safety issues,the safety of the food and vegetables the main problem is the use of pesticides.The use of pesticides problem is mainly the maximum residue limits of grain and vegetables(MRL). Three azole pesticide in the plant has shown unprecedented sterilization effect, make it have a lot use of space. It is necessary to establish a three azole pesticide detection method for food and vegetables, and has a high sensitivity and accuracy of qualitative and quantitative.Gas chromatography-mass spectrometry2(GC-MS2) is a second choice of a new kind of detection method, can reduce the background interference, and obtain more accurate results. This experiment mainly aimed at the food and the onion garlic in18species of triazole fungicides pesticide residue detetion, determine the solid gel permeation chromatography(GPC) and GC-MS/MS detection conditions. Specific experiment and test results are as follows:This study makes the reception of the mobile phase of GPC through the observation of grain and onion matrix of GPC and standard GPC figureof18kinds of pesticide.About solvent contrast, form acetonitrile GPC diagram, acetonitrile is the most suitable. Because food kind sample moisture content is less. Wetting samples of water,but water more, pesticide loss,5mL is the more appropriate.The dosage of the solvent effect on the recovery rate is not, but form the experiment process, choose to25mL. About extraction way from oscillation and ultrasonic and homogenate, homogenates is uniform, efficient, time-saving and labor-saving. Due to water and acetonitile is infinite mutually soluble, so usually choose centrifugal separation method, funnel to acetonitire volatilization and recovery is not good. SPE(solid phase extraction) and GPC purification principle is different, so the suity to object is also different,GPC is suitable for purifying grain and oil containing a higher proportion of large molecules, such as material, the SPE is typically used for substances such as vegetables and fruits. For mass spectrometry detection method SRM(selectivity reaction monitoring) has higher selectivity than full scan, and low baseline and requirements of peak shape conforms.Onion garlic class object detection is a kind of relatively special vegetables that contain a smell, when cells rupture enzymes react with some substances generated with the known material to be detected substance. Destroying enzyme to block the reaction, enzyme inactivation has several methods such as microwave and acid solution. Triazole fungicides is a kind of stable pesticide, this kind of fungicide in the100s will not be change. Microwave has several adjustable gear, medium and high fire archives of GPC purification effect is better. Microwave heating time on purifying effect may also be affected, in a certain range, the longer, the better purifying effect. Because ginger contains pigment,so it need to affer the GPC,and decrease as far as possible in the SPE column background interference.The coefficient of standard curve and the related experiment to determine the appropriate concentrations of18kinds of pesticide standard range. Second, the matrix effect exists generally in chemical analysis, especially in trace and trace analysis influence particularly large. This experiment in rice, wheat, soy, peanuts, onion and ginger matrix and18kinds of pesticide standard comparison,there were different degrees of matrix effect. This experiment choice matrix with standard correction method to reduce the influence of the substrate.This experiment according to the established experimental conditions and instruments test conditions,do rice,wheat,soy, peanuts, onion and ginger, respectively select three concentrations of standard addition recovery rate,results of18species of three azole pesticide recovery range80-120%, Relative standard deviation range0-20%. Detection limit is0.06-0.6ug/kg. |
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