Study On The Determination Of Residue And Degradation Of 10% Iprodione EC In Pear And Soil

Iprodione is a broad-spectrum, low toxicity, heterocyclic fungicide. It is commonly used in the pear production, and has obvious effect to control scab of pear. This paper established a gas chromatographic method to determine residue of iprodione in pear and soil. The influences of dosage and spraying times on degradation of iprodione in pear and soil were investigated with 10% iprodione EC. The safety of applying this fungicide was assessed. This study is important to improve quality and safety of pear products. The results are as follows:1. The analytical method of iprodione residue in pear and soil was established with gas chromatography. Iprodione was firstly extracted from pear and soil samples with acetonitrile, After being concentrated by evaporation, purified by the Florisil SPE column and detected by GC-ECD. The results showed that the linear relationship between peak area and iprodione content was good and the minimum detectable amount was 0.005 ng. For pear samples, the minimal determination concentration of this method was 0.01mg/kg, and the average recoveries were from 94% to 107% with RSD from 3.2% to 6.5%. For soil samples, the minimal determination concentration was O.Olmg/kg, and the average recoveries were from 98% to 110% with RSD from 4.0% to 10.5%. The sensitivity, accuracy and precision of this method are consistent with requirements of pesticide residue testing.2. Degradations experiments of iprodione in pear and soil were achieved in two pieces of field in Gaocheng and Handan city. The pear and soil were treated with the pesticides at 1.5 times of the recommendation dosage. The pear and soil samples were collected at different times after application, and analyzed by the developed method. The half-life of iprodione in the pear was 12d, and its residue was lower than 10% after 45d from application. The half-lives in soil were 7.8d～7.9d, and its residue was lower than 10% after 45d from application. The results showed that iprodione was easy to degrade in pear and soil.3. After being respectively sprayed 10% iprodione EC on pear and soil with three or four times at two dosages, the samples of pear and soil in harvest time were collected and detected. The results showed that the final residues in pear were 0.14 mg/kg and 0.37mg/kg in two places at 21d, respectively. And the final residues in soil were 0.057 mg/kg and 0.14mg/kg in two places, respectively. These indicated the final residues in pear and soil are related to spraying dosage.4. The spraying times had effects on pesticide residue in pear. The initial residues of iprodione were highly different between three times and four times, but the difference was smaller and smaller with time. The final residues increased with spraying times and decreased with haverst time.5. This work invovled in degradation, preharvest interval and final residues of iprodione in pear and soil. It is very important for guiding farmers to scientifically and rationally use iprodione, and produce pollution-free pear products, and ensure people's health.