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Analysis of pesticide residues is the first link in the extraction and purification from the sample trace of pesticides, and a direct impact on the quality of the extracted accuracy of the results. Currently pesticide residue analysis frequently used methods require sample purification treatment, or a large number of impurities only interfere with the analysis of pesticide residues and will damage the instrument. Therefore, extraction, concentration and purification of pesticide residue analysis is a very important pre-processing steps. Cloud point extraction in recent years, the emergence of a new liquid - liquid extraction techniques to aqueous surfactant micelles solubilizing and cloud point of the phase behavior, based on the hydrophobic and hydrophilic material separating substances. As a means of separation and enrichment, high cloud point extraction with extraction, enrichment factor, simple operation, safe, economical, easy to implement combined with other advantages. This article will cloud point extraction for trace enrichment of organophosphorus pesticides. The text of the six common nonionic surfactant cloud point temperature, the solubilizing power, phase characteristics were studied and compared. The results show that, C 12 E 10 has good solubilizing ability by adding appropriate amount of Na 2 SO 4 can Cloud point to room temperature and level control, phase after photogenic as a sticky solid. TX-114's own cloud point temperature of 23 ° C, at lower phase after phase separation, cryogenic cooling, carefully pour the water phase after the separation of the two phases can be achieved. Since C 12 E4 and the aqueous phase density close to the body, regardless of room temperature phase, C18E 10 , C 12 E23, TX-114 (Na 2 SO 4 ) condensed phase after phase separation liquidity, easy sampling, affect the accuracy and repeatability of experiments, it is not suitable for use in the experimental operation. Methyl parathion to be selected for the extraction of pesticides, by varying the initial concentration of the surfactant, phase temperature, Na 2 SO 4 and the added amount of the phase separation conditions enhance extraction efficiency. At 35 ° C, C 12 E 10 concentration of 5g · L-1, Na 2 SO 4 Add amount of 120g · L-1, phase separation by centrifugation, extraction rate can reach 90.29%. TX-114 concentration was 20 g · L-1, 35 ° C stationary phase separation, the extraction rate of 85%. And TX-114 compared to, C 12 E 10 -Na 2 SO 4 system has a small condensed phase enrichment factor large, phase quickly, easily and Liquid Chromatography advantages. Cabbage samples for pesticide spiking experiments, from the method sensitivity, accuracy and precision aspect verify the feasibility of cloud point extraction. Using C 12 E 10 -Na 2 SO 4 System cabbage samples after cloud point extraction of methyl parathion , ethyl parathion, phoxim, the lowest detection limit can reach 0.0008mg/kg, can meet the national requirements of the maximum allowable residue limits (0.01mg/kg).
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