Dynamic study on the residue detection and degradation of pentachloronitrobenzene in watermelon and soil

The present paper is aimed at introducing the findings of our dynamic research on the residue detection and degradation of pentachloronitrobenzene (PCNB)in watermelon and soil.In our research we have adopted an analytical method of gas chromatography so as to determine the pollution and degradation trends of the PCNB residue in watermelon and soil.The experimental results of our experiments and testing prove that the average recovery rate of PCNB is in a range of 83.41%-93.17% at the three spiking levels from 0.01 mg/kg to 0.50 mg/kg with their relative standard deviations of 3.37 %- 9.74 % in watermelon and soil.The detection limit turns to be 1.2× 10~(-12)g whereas the minimum mass ratio detected was 0.001 mg/kg in watermelon and 0.005 mg/kg in soil,respectively.A control and contrast trial experiment in Shandong province and Zhejiang province was done with the finding results as follows:the degradation regulation of PCNB in watermelon and soil conformed to the first order kinetics reaction model,with its half-life being 4.13-6.08 d,3.67- 4.92 d in the soil and the watermelon,respectively.Our research also shows that,when 40% carbendazim pentachloronitrobenzene wettable power was applied once and twice at an interval of 7 d with the dosages of 0.83_1.24 g/strain in the whole culture process,on the 7th day after the last application,the MRLs of PCNB would drop below 0.1 mg/kg in the fruits and vegetables in accordance with the Chinese standard.Thus,it can be said that our experiments provide valuable scientific data for registration and secure application formulate of 40% carbendazim pentachloronitrobenzene wettable power, so as to protect agricultural environment and human health.