Solid Phase Extraction Technique And LC-MS/MS In The Application Of Analysis Pesticide Residues In Tea

Tea is one of the important agricultural products and traditional export commodities in China. However, with the development of agricultural industrialization, various pesticides have been widely used during the cultivation and storage of tea, which is a potential threat to the health of tea drinkers. At the same time, tea import country especially economically developed countries product tea very few or even didn’t product tea, many countries and international organizations have established potential international trade barriers like strict maximum residue levels (MRL) standards. For example, in recent years European Union (EU) has established the maximum residue levels of most pesticides in tea and the MRLs are periodically revised and become more strict and comprehensive. That is also a serious threat to the development of China’s agricultural products trade.Methods of pesticide residues determination are concentrated in analysis of milk, vegetable and fruit samples, however reports concerning the detection of pesticide residues in tea, especially for the simultaneous determination of pesticide residues are very few. The detection methods of pesticides are commonly gas chromatography (GC), gas chromatography-tandem mass spectrometry (GC-MS/MS) and etc.. In recent years, liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS) for wide usage and high sensitivity, good repeatability are widely used in food safety analysis. Tea samples has the complexity of matrix, not only contains a lot of pigment, but also containing alkaloids, caffeine, tea polyphenols and other components, the matrix will interfere the process of chromatographic analysis, so the purification of tea extract has always been a difficulty of residues analysis in tea sample. And solid phase extraction method was widely used in the process of sample preparation as the advantages of less solvent consumption, convenient operation.The first chapter of this paper mainly introduced the situation of import and export trade of tea, the usage of three kinds of pesticides in tea, we comparative analysis of the most common instrument in detection of pesticide residue in tea and tea sample pretreatment method.Chapter two establishes the composite solid phase extraction-high performance liquid chromatography tandem mass spectrometry-isotope internal standard method analysis of32organophosphorus pesticide residues in tea,by using organophosphorus isotope internal standard calibration, comparing the extraction efficiency of different solvent systems, different solid phase extraction columns and the analysis of the instrument conditions are also optimized, finally we established a rapid detection method of a variety of organophosphorus pesticide residues in tea, the method of quantitative detection limit (LOQs) are less than8.0mg/kg.The chapter three establishes the molecularly imprinted solid-phase extraction and high performance liquid chromatography tandem mass spectrometry method of determination of phenoxycarboxylic acids pesticide residues in tea, we discussed the optimization of the molecular imprinting process and compared with other solid phase extraction column, and optimized the conditions for instrument analysis, the method has low detection limit, the compounds of standard addition were between96.4%and102.8%, recovery is suitable for the rapid analysis of phenoxycarboxylic acids in complex matrix samples.The chapter four discussed the molecularly imprinted solid phase extraction-liquid chromatography tandem mass spectrometry method in analysis of chloroacetanilide pesticide residues in tea, a detailed study of the adsorbent dosage, durable performance of the molecularly imprinted solid-phase extraction column and performance corporation with other solid phase extraction column, the result of the method for purification of tea matrix is good, the recovery rate of the detect compounds in the range of94.3%to97.1%, this method is rapid, accurate, sensitive, and can meet analysis requirements of a trace level of chloroacetanilide pesticide residues in tea samples.