Residue Analysis And Digestion Dynamics Study Of 330g/L Pendimethalin Emulsifiable Concentrate On Potato

Pendimethalin is a member of the dinitroaniline herbicide and has been used for controlling weeds in the fields for production of many crops.At present,China has not yet developed the maximum residue limit?MRL?of pendimethalin on potato.In this paper,a simple and sensitive GC-MS method was developed for the detection of pendimethalin in soil,potato and potato foliage.The field trails were conducted in Guizhou and Anhui province during the agricultural season in 2015 and2016 to determine the dissipation dynamics and terminal residue of pendimethalin in potato and soil.In this experiment,soil samples was extracted by ethyl acetate;Potato and potato foliage samples were extracted twice by homogenate with acetonitrile.Then the solution was concentrated on the rotary evaporator and analyzed by GC-MS.The results showed that the limits of detection?LOD?was 1.0×10^-11 g.The limit of quantification?LOQ?was 0.005 mg/kg in soil,potato and potato foliage.The recoveries of matrixes were ranged from 78.28% to 107.37% with RSD from 1.47%to 9.22%.The method was suitable for pendimethalin determination in field samples.The results showed that the final residues of pendimethalin in all potato samples was below 0.005 mg/kg at harvest time?the dosage was 900¹485 g.a.i./ha and applied one time?,which was much lower than the MRL of European Union?0.05mg/kg?.Therefore,330 g/L pendimethalin EC can be applied safely on potato with the recommended dosage and time.Moreover,in order to explore the environmental factors for the degradation of pendimethalin in soil,indoor simulation experiment was designed.The result showed that when the moisture content was 24%,32% and 40%,the half lives of pendimethalin in soil were 26.67 d,18.24 d and 17.32 d,respectively.When the fortified concentrations gof pendimethalin were 0.5,2.0 and 5.0 mg/kg,the half lives were 13.86,18.24 and 23.93 d,respectively.In the sterilized soil the half lives of pendimethalin was 46.21 d and in the unsterilized soil the half lives of pendimethalin was17.77 d.The half lives of pendimethalin were 19.80 d,19.25 d,18.24 d and 24.76 d in Anhui,Guizhou,Shandong and Heilongjiang soil,respectively.In a word,lowercontent of pendimethalin and higher water content the pendimethalin degraded faster in unsterilized soil in our research.