Study On Residue Analysis And Digestion Of 20% Methicloxacillazole Suspension In Tomato

Jiahuangxianjunzuo(JHXJZ) is a new oxadiazole fungicide, which was developed by the Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University. It mainly prevents and cures tomato bacterial wilt(Pseudomonas solanacearum), tobacco bacterial wilt(Ralstonia solanacearum), and Xanthomonas oryzae. To date, although other classes of fungicide have been reported, however, few analytical methods have been reported in the literature for determination of JHXJZ on tomato. Some relevant articles reported that JHXJZ has a similar structure(containing 1, 3, 4-Oxadiazole) with oxadiazon. Thus, we could take advantage of some useful information of oxadiazon for JHXJZ study.The tomato and soil were extracted with ethyl acetate without further clean up. Then the residues of JHXJZ were determined by UPLC-PDA. The results showed that the external standard curve showed a good linearity 0.50~20.0 μg/mL with the correlation coefficient of 0.9999 for tomato, and 0.10~20.0 μg/mL with the correlation coefficient of 0.9996 for soil. The spiked levels of JHXJZ were from 0.025 to 0.5 mg/kg in tomato, from 0.005 to 0.5 mg/kg in soil. The average recoveries of tomato and soil were studied at three spiking levels and ranged from 84.51 to 101.30% and 85.30 to 101.53%, respectively, with relative standard deviations of 2.61 to 4.13% and 1.21 to 4.80%, respectively. The accuracy and sensitivity of the method meet the requirements of pesticide residues analysis.The field trials of 20% JHXJZ(SC) were performed in Guizhou, Guangxi and Tianjin province during the agricultural season in 2013 and 2014. The residues of JHXJZ in tomato and soil were carried out. The results presented that JHXJZ residues in the tomato and soil in Guizhou, Guangxi and Tianjin were not detected at harvest after spraying in 2013 and 2014. The obtained data from this study may help the relevant sector establish a MRL of JHXJZ in tomato.Moreover, the thermodynamics of degradation behavior of JHXJZ indoor were investigated for the first time. The result showed the non-sterilized soil, the higher environmental temperature, pH and moisture content, the faster speed of JHXJZ degrade.