Application Of Liquid Phase Microextraction For The Determination Of Multiple Pesticide Residues In Water,Strawberry And Apple Cider Vinegarin

With the improvement of people’s living standards, humans began to pay more attention to improving the quality of life. However, worldwide food safety issues have become increasingly prominent, especially the problem of excessive pesticide residues is more serious, which constitutes a serious threat to human and animal health. Countries around the world are gradually establishing the related legislations of the maximum residue limits of pesticides in food, which caused certain influence to the exporter. Therefore, to ensure the normal commercial intercourse between our country and other countries, it is imperative to strengthen supervision and inspection of pesticides in food; to establish a simple, rapid, accurate and sensitive method of detection is the mission our scientific research workers should assume. In this paper, based on the liquid phase microextraction（liquid phase microextraction, LPME） combined with gas chromatography-mass spectrometry（GC- MS）, the analysis and research of the pesticide in food（water, strawberry, apple cider vinegar） were carried out. The main researches are as follows:A simple and rapid method for the simultaneous determination of seven herbicides in water was established through dispersive liquid-liquid microextraction（DLLME） combined with GC-MS. The mixture of extraction solvent and dispersive solvent was quickly injected into the water sample, and after centrifugation, the extraction phase was analysed by GC-MS. Several parameters influencing the extraction efficiency were optimized and the optimized extraction conditions were as follows: chloroform（CHCl₃） as the extraction solvent, methanol（CH₃OH） as the dispersive solvent, 80 μL of CHCl₃, 800 μL of CH₃OH. Under the optimal conditions, the recoveries of all pesticides at three spiked concentrations were in the range of 82.9 117.3% with the relative standard deviations（RSDs） of less than 11.9%. All pesticides detected in the concentration range（0.01 5.0 mg/L） showed good linearity with the coefficients of determination（R2） greater than 0.9982, detection limits of 0.036 0.243 μg/L. This method has been successfully applied to the analysis of water samples（paddy irrigation water, paddy field water, river, lake and tap water）.A method of modified quick, easy, cheap, effective, rugged and safe method（Qu ECh ERS） combined with vortex-assisted dispersive liquid-liquid microextraction（VADLLME） was establishesd to simultaneously determine 8 fungicides in strawberry through GC-MS. First, sample was extracted by acetonitrile, and then a fraction of the extract as the dispersant was subjected to VADLLME. Finally, the sedimented phase was analysed through GC-MS. The main factors affecting the extraction efficiency were optimized, and the optimal extraction conditions were as follows: 5 m L acetonitrile, extraction time 20 min, 100 mg PSA purification, methylene chloride（CH₂Cl₂） as the extraction solvent, 100 μL of CH₂Cl₂, 1000 μL of acetonitrile extract（dispersant）, vortex time 45 s. Under the optimized conditions, the recoveries of all analytes at three spiked levels were 72.6 96.9% with RSDs always less than 12.2%. Matrix-matched calibration solutions of eight pesticides within the concentration range of 0.05 5.0 mg/L showed good linearity with R2 greater than 0.9951; the limits of detection were 0.58 1.68 μg/kg, presenting the high sensitivity of the method. This method has been successfully applied to the analysis of real samples.A rapid and sensitive method for the simultaneous determination of seven kinds pesticides in apple cider vinegar was established through vortex-assisted liquid-liquid microextraction（VALLME） combined with GC-MS. The extraction solvent was injected into the apple cider vinegar sample. After vortexing and centrifugation, the sedimented phase was determined by GC-MS. Several parameters influencing the extraction efficiency were optimized, the optimized conditions were as follows: chlorobenzene（C₆H₅Cl） as the extraction solvent, without salt, 120 μL of C₆H₅ Cl, vortex rate 2500 r/min, extraction time 60 s. Under the optimal extraction conditions, the recoveries of all pesticides at three spiked concentrations were in the range of 71.4 106.8% with RSDs less than 11.3%. Among the studied seven pesticides, chlorpyrifos, triadimefon and chlorfenapyr showed a good linear relationship in the concentrations of 0.05 5.0 mg/L, while procymidone, hexaconazole, diniconazole and pyridaben exhibited a good linearity in the 0.01 5.0 mg/L concentration range, with determination coefficients greater than 0.9984; this method has higher sensitivity and detection limits of 0.23 0.85 μg/L. The method was successfully used for the analysis of real samples, and no analytes were not detected in all samples.