Study On The Residual Behavior Of Acetamiprid And Fenobucarb In Rice, Soil And Paddy Water

A new method was developed for the residual analysis of acetamiprid and fenobucarb in rice,soil and water in this paper. The degradation dynamics and final residue ofacetamiprid andfenobucarb in rice were investigated in field experiment done in Tianjin, Zhejiang and Shandong.The results can provide important scientific bases for MRL for acetamiprid and fenobucarb andsafe use regulation for22%acetamiprid andfenobucarb EC in rice. It is of significance for theprotecting agricultural environment, promoting the rice production safety and assuring humanhealth.1. A new method was developed for the residual simultaneous analysis of acetamiprid andfenobucarb by gas chromatography (GC). The samples of soil and filed water were extracted byacetone and petroleum ether (v:v=1:2)and then extracted by methylene chloride, concentrated andthen determined by GC with NPD. The sample of rice, rice husk and plant were extracted byacetone and petroleum ether (v:v=4:6)and purified through florisil solid-phase extraction column,concentrated and determined by GC with NPD. This method has high sensitivity and accuracyisaccurate and rapid, which can satisfy the demand of pesticide residual analysis.2. The residual degradation dynamics and final residues of22%acetamiprid and fenobucarbEC in rice and soil were studied by a two-year and three-field experiments in Tianjin, Zhejiangand Shandong. The rice, soil and paddy water were treated with the pesticides at1.5times of therecommendation dosage. It was found that the residual degradation dynamics can be fit by the firstorder dynamics: C=C0e-kt. The half lives of acetamiprid and fenobucarb are less than30days, sothey could degrade in rice, soil and paddy water easily.3. The rice and soil were treated with the pesticides at normal and1.5times of therecommendation dosage in the final residual experiment. The rice and soil samples were collectedon7d,14d and21d after the last spraying. The results showed that the maximum residue limits(MRL) of acetamiprid and fenobucarb in rice on21days after the last spraying were0.419mg/kgand0.054mg/kg, respectively. They are lower than the MRL for acetamiprid in wheat (0.5mg/kg)in the national agricultural standard “maximum residue limits for pesticides in farmproducts”(NY1500.1.1-1500.30.4-2007)acetamiprid in wheat (0.5mg/kg), and the MRL forfenobucarb in unpolished rice in food for fenobucarb in unpolished rice (0.5mg/kg) in the nationalstandard “Maximum residue limits for pesticides in food”(GB2763-2005), respectively.4. The distributions of acetamiprid and fenobucarb in different parts of rice were studied. Theresults indicated that the distribution ratios of acetamiprid and fenobucarbin rice hull were thelargest, which were significantly higher than those in the unpolished rice. The rice hull and plantare the main residual accumulation parts which bore most pesticide residue.