| An HPLC-MS/MS method for determination of chlormequat chloride, 6-benzylaminopurine, forchlorfenuron, paclobutrazol, uniconazole, gibberellin, 4-chlorophenoxyacetic acid、2,4-D residue in tomatoes and cucumbers was developed in this study. And the dissipation dynamic and terminal residue of Gibberellin, Paclobutrazol, Chlormequat Chloride was also evaluated in Guangzhou during year 2014 and 2015. The results were as follows:(1) A simple method for analysis of 8 plant growth regulator in tomato and cucumber sample by HPLC-MS/MS was developed. The results showed that when spiked at level of 0.01、0.10、0.50mg/kg, the average recoveries of the plant growth regulator in tomato and cucumber were 87.22~109.96% with relative standard deviation(RSD) of 1.47~10.06%, and 92.24~111.12% with RSD of 0.98~11.36%, respectively.(2) The dissipation experiment indicated that dynamic of the Gibberellin, Paclobutrazol, Chlormequat Chloride followed the first-order chemical kinetic equation Ct=Coe-Kt. The half lives of the 3 plant growth regulator were 1.8, 1.2 and 2.2 days, respectively.(3) The terminal residue experiment showed that when applied at the recommended dosage and 1.5 times of recommended dosage, the reminal residue of Gibberellin, Paclobutrazol and Chlormequat Chloride were 0.02~0.67mg/kg,0.02~6.02mg/kg,1.02~10.27mg/kg after application of 3、5 and 7d. and were all below 0.01mg/kg after 3、5 and 7days of harvest.(4) MRL of Gibberellin in fruits were set at 0.2mg/kg by United States and Japan. The MRL of Paclobutrazol in fruits(eg. apples and lichis) set in “National Food Safety Standard-Maximum Residue Limits for Pesticides in Food”(GB2763-2014) was 0.5 mg/kg. It can be conclude that the recommend application dosage of 3% Gibberellin, 15%Paclobutrazolwettable powder and 50%Chlormequat Chloride aqua is 1.5 to 2.25 g a.i./hm2, 25 to 37.5g a.i./hm2, and is 37.5 to 56.25 g a.i./hm2, respectively. |
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