| At May 2003, Japan revised Food Sanitation Law and began to implement agricultural chemicals Positive List System in food from May 29, 2006. The implementation of this system has caused great influences on our country's food export to Japan. The Positive List System is a new system set by Japan in order to strength agricultural pesticide (including pesticide, veterinary medicine and feed additive) residue management in food. In the draft of Positive List System announced at 2005, Japan raised original limit standard to 799 kinds of pesticides and veterinary medicines and 53862 limit standards. The amount and strictness of limits is unprecedented. This system had been implemented at May 2006. After the implementation of this trade barrier, only from June to August 2006, the whole amount and value of vegetables export to Japan both slip more than 30%, which resulted in great economic losses.Japan is the biggest market to our country's food and agricultural products. In the case of Weifang City, at 2005 the fresh vegetables exported to Japan reached 10829 batches, 274 thousand tons in weight and 130 million US dollars in value, which accounted for 58%, 56% and 56% of the total amount of exported fresh vegetables respectively. Japan market has irreplaceable effect on agricultural development and economic development of Shandong province. As a large agricultural products-export province, it has important effects for promoting import and export trade of Shandong province to study the Japanese trade barriers.Among the 799 agricultural chemicals involved in current Positive List System, there still are 391 kinds of pesticides and 155 kinds of veterinary medicines that have not been set up detection methods, which account for 62.1%. So the standard-setting work is extremely Urgent. It is very difficult to set up so many absent detection standards in labor resources, materials and money. In order to make the Positive List coping work to be more targeted, we carried out statistic collection to the pesticide items in the list and pesticide varieties that are circulated and used at current market. There are 113 kinds of pesticides. Among these pesticides, 56 kinds (methamidophos, ddv, eptc, eradicane, mevinphos, butylate, acephate, pebulate, molinate, dimethoxon, tetrachloronitrobenzene, cycloate, monocrotophos, phorate,α-benzene hexachloride, dimethoate,β-benzene hexachloride,γ-benzene hexachloride, fonofos, chlorothalonil, pyrimethanil, disulfoton,δ-benzene hexachloride, pirimicarb, iprobenfos, chlorpyrifos-methyl, parathion-methyl, sumithion, malathion, aldrin, chlorpyrifos, diethofencarb, parathion, quinalphos, p, p'-dde, p, p'-dichloroethylene, dieldrin, endrin, flusilazole, o,p'-ddt, p,p'-ddd, ethion, triazophos, carbophenothion, p, p'-ddt, bifenthrin, fenpropathrin, beta-cypermethrin, permethrin, baythroid, cypermethrin, flucythrinate, fenvalerate, tau-fluvalinate, decamethrin) are still have not detection standards or the detection precision of standards is comparatively low. All these pesticides are the emphasis being focused and detected by the international plane, especially by Positive List System. Every country has strictly stipulated the limit of the above-mentioned pesticides in vegetables and monitored emphatically. In recent years, Japan gave warnings from time to time, which brought great difficulties to our country's vegetables export. For the sake of successfully exporting of our country's vegetable products, it is extremely urgent to investigate the rapid and accurate analysis methods targetedly to analyze the above-mentioned pesticide residues in vegetables.At 2003, the chemist Steven J.Lehotay at Pennsylvania, USA and visiting scholar Michelangelo Anastassiadas from Germany put forward QuEChERS multiple pesticide residues simultaneous analysis method. At present, the major action applied is QuEChERS pre-treatment technology. QuEChERS means "quick, easy, cheap, effective, rugged and safe", which is a quick, simple and low-cost sample treatment method. The key of this method is to adopt dispersive solid-phase extraction (dispersive-SPE) purification method, mix magnesium sulfate and PSA absorbing agent powder directly into partial extracting solution after acetonitrile oscillation extraction for purification, then analyze the supernatant fluid after centrifugation with instruments. This method replaces the corresponding SPE cartridge purification, has the advantages of quickness, simpleness and economy, and also has the shortcomings that detection limit could not meet the requirements, moisture may not be removed thoroughly, extraction rate might be low and purification effects may be less than ideal. Because QuEChERS is the newly appeared sample treatment technology in recent years and it has limitations, at present only less application has been carried out in our country. On account of the limitations of this method and combined with Positive List, we improved the sample extraction and purification. Besides PSA powder, we took into account the mixture several absorbing agents including graphite carbon black powder, ODSC18 and amino-propyl powder and divided the specific operation procedures according to different sample substance, which significantly improved the extraction rate and purification effects. Through nitrogen evaporation and revolving steaming condensation, the sensitivity got 4-5 fold increases and through solvent replacement, this technology could integrate more analysis instruments for detection. We firstly developed the pesticide residue detection project development of three pesticides, dieldrin, endrin and aldrin, carried out the detection of organic phosphorus pesticide and organic chlorine pesticide with improved QuEChERS sample treatment technology combined with GC-FPD and GC-ECD separately, and carried out multiple residues simultaneous detection of many kinds of pesticide chemicals such as organic phosphorus pesticide and organic chlorine. All the combinations obtained satisfying results. We further applied this method into the analysis of veterinary residue and carried out simultaneous detection of sulfa, diclazuril and clopidol in poultry meat combined with HPLC. The result is equally satisfactory.Through the development and application of this project, the exported food value of Shandong province amounted to 10.665 billion US dollars, increased 21.6% accounting for one-quarter of countrywide food and agricultural products export, and constantly realized high growth under high-entry barrier for six years. The food export has settled the employment of 14 million people and strongly boosts the resolve of agriculture, countryside and farmers issues. |
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