| A method was established for determination of thiophanate-methyl in asparagusand its cultivated soil by PSA dispersive solid phase extraction and ion-paring HPLC.Degradation dynamics and final residue of thiophanate-methyl in asparagus werestudied in this paper. The main results were summerised as follows:(1). Residues of thiophanate-methyl were extracted with acetonitrile,45mgPSA and180mg anhydrous magnesiμm sulfate were added to the supernatant extract. Aftershaking and centrifuging, the extract was mixed with ion-pairing reagent anddetermined by HPLC equipped with PDA. The results showed that the method wassuitable for drawing samples. The minimum detectable quantity and concentration ofthis method were7.5×10-9g and0.01mg/kg, respectively. Within the compass of0.1mg/L～20mg/L, R2=0.9982, linear relation was fine. The residue digestion ofthiophanate-methyl and final residue trials in asparagus were quantitatively surveyed inFujian and Shanghai provinces.(2). The addictional and recovery experiments showed that the average rate of recoveryof thiophanate-methyl in asparagus, asparagus plant and soil were respectively from73.12%to83.55%,73.43%to83.94%and75.53%to85.68%. The RSD of recovery ofthiophanate-methyl in asparagus, asparagus plant and soil were separately from2.68%to3.98％,2.01％to3.04％and1.46%to3.75％. The method could be adapted to thetechnical requirement of pesidues residue detection in repeatability, reproducibility,precision and accuracy.(3). In2009, the degradation dynamics experiments showed that the quantity of originalaccumulation of70%thiophanatemethyl WP in asparagus were separately1.20mg·kg-1(Fujian) and1.16mg·kg-1(Shanghai). The half-life of thiophanatemethyl inasparagus were1.62d (Fujian) and1.72d (Shanghai). The quantity of originalaccumulation of thiophanatemethyl in soil were2.91mg·kg-1(Fujian) and0.38mg·kg-1(Shanghai), separately. The half-life of thiophanatemethyl in soil was1.36d (Fujian)and2.79d (Shanghai). In2010, the degradation dynamics experiment showed that thequantity of original accumulation of70%thiophanatemethyl WP in asparagus plantwere2.90mg·kg-1(Fujian) and2.20mg·kg-1(Shanghai), separately. The half-life of thiophanatemethyl in asparagus was2.54d (Fujian) and2.02d (Shanghai). The quantityof original accumulation of70%thiophanatemethyl WP in soil were separately2.75mg·kg-1(Fujian) and0.39mg·kg-1(Shanghai). The half-life of thiophanatemethyl in soilwere1.31d(Fujian) and2.29d(Shanghai).(4). The final residue experiments showed that the final residue quantity of asparagusand soil hadn't been detected while the recommended highest concenteation and its1.5times were used after7days. |
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