Residues And Degradation Of Herbicides Commonly Iised In Yralic Field

Pendimenthalin, Oxyfluorfen and acetochlor are herbicides commonly used in garlic fields. Theyhave commendable control efficiency to many kinds of weeds in garlic fields. They have longpersistence. In this paper, we have done field tests about44%Pendimenthalin, Oxyfluorfen andacetochlor EC in Qingdao, Shandong province for two years. We have studied the analytical method,dissipation dynamic and final reidue of these compounds in garlic and soil. Based on the 《Rules ofPesticides Residue Field Test》 to spray and sample, optimized the condition of instrument and methodof pretreatment. We choose the GC-ECD to detect samples. The data has provided reliable basis to theuse of pesticides. The research results are as follows:We have built a method to detect Pendimenthalin, Oxyfluorfen and acetochlor these threecompounds that use GC-ECD at the same time. In these chromatograph conditions, the retention time ofPendimenthalin is19.16min, Oxyfluorfen is21.82min and the acetochlor is16.05min. Through thechecking of recovery test, the recovery of these three compounds were at the range of85%to115%with the RSD%at the range of2.88%~11.28%, which indicates that this method were accuracy. Thelimits of detection of these three pesticides were2.0×10-3ng、1.0×10-3ng and3.0×10-3ng respectively.The additional recoveries of these three herbicides all were0.02mg/kg. The results are all up to themustard. The method are sensitive, precise, accurate and typically. It is up to the rule of residue standardand can be widely used.Based on conditions above mentioned, samples were detected for their dissipation dynamics andfinal residues. We spray at the time of seeding in fall.The results show that after spraying, when wesampled for the first time at next year summer, there isn’t compounds in garlic sample but still haveresidue in soil samples. And these three compounds in soil samples were conformed to the kineticequation. The final residue shows that after once spraying, these compounds do not have residues ingarlic sample. But we also can detect residue quantities in soil. In order to avoid influencingnext-stubble crops, therefore, we command that using the44%Pendimenthalin, Oxyfluorfen andacetochlor EC to weeding at the dose of990-1155g a.i/ha of active principle, spraying once andsampling after200days are secutiry.