代森联和乙撑硫脲在西瓜和土壤中的消解及安全性评价

Dissipation Dynamics and Safety Evaluation of Metiram and Ethylene Thiourea in Watermelon and Soil

[目的]研究代森联和乙撑硫脲在西瓜和土壤中的消解与残留变化趋势，评价代森联和乙撑硫脲在西瓜上使用的安全性。[方法]样品经液相色谱测定。[结果]西瓜中代森联的原始沉积量为1．19-2．01mg／kg，半衰期（t1/2）为4．2-9．0d；土壤中代森联的原始沉积量为1．02～2．83mg／kg，t1/2为4．6-5．4d。用药0．042d后，乙撑硫脲在西瓜中的残留量为0．07-0．13mg／kg，t1/2为2．2-2．9d；在土壤中的残留量为0．07-0．19mg／kg，t1/2为2．6～2．8d。施药间隔7、14、21d，代森联在西瓜、瓜瓤和土壤中的残留量〈1．0mg／kg，乙撑硫脲在西瓜、瓜瓤和土壤中的残留量〈0．02mg／kg。[结论]参照我国规定代森联在西瓜上的最大残留限量（MRL）为1mg／kg，以及欧盟规定乙撑硫脲在植物性食品上的MRL为0．05mg／kg的标准，60％吡唑醚菌酯·代森联可分散粒剂按推荐剂量和方法使用，间隔7d后的西瓜是安全的。

[Aims] Dissipation dynamics and final residues for metiram and ethylene thiourea in watermelon and soil were investigated to provide an evaluation for the safe use of metiram and ethylene thiourea in watermelon. [Methods] Samples were determined by HPLC. [Results] The original deposit amounts of metiram in watermelon ranged from 1.19 to 2.01 mg/kg. The half-lives ranged from 4.2 to 9.0 days. The original deposit amount of metiram in soil ranged from 1.02 to 2.83 mg/kg. The half-lives ranged from 4.6 to 5.4 days. The residue amounts of ethylene thiourea in watermelon ranged from 0.07 to 0.13 mg/kg after spring 0.042 day. The half-lives ranged from 2.2 to 2.9 days. The residue amounts of ethylene thiourea in soil ranged from 0.07 to 0.19 mg/kg after spraying 0.042 day. The half-lives ranged from 2.6 to 2.8 days. After spraying 7, 14 and 21 days, the residues of metiram and ethylene thiourea were below 1.0, 0.02 mg/kg, accordingly. [Conclusions] The residues of metiram were below the maximum residue limit set by China （MRL, 1.0 mg/kg） and the residues of ethylene thiourea were below the maximum residue limit set by EU （MRL, 0.05 mg/kg）, which suggested that this fungicide was comparably safe to apply in watermelon when sampling 7 days after the final application.