Residue Determination Of Mancozeb And Its Metabolite ETU In Several Kinds Of Agricultural Products

Mancozeb is an important fungicide which has been widely used to control the various diseases in vegetables and fruits for decades.However, unreasonable and misused application of mancozeb resulted in the overdosed residues of the parent and its metabolite ethylenethiourea (ETU) in agricultural products, environmental pollution and human healthy problems. A method was developed for the determination of germicide fungicide mancozeb and ETU residues in the five agricultural products such as tomato, cucumber, pear, bean and banana, respectively, using headspace gas chromatography (HS-GC) and high performance liquid chromatography (HPLC), and monitoring of fungicide mancozeb and ETU residues in tomato, cucumber, pear, bean and banana collected from the product growing regions and supermarkets all over the country from 2009～2010, in order to provide technological support for revision and drafting of residue tolerance through monitoring of the mancozeb and its ETU residues in the agricultural products,. Research results can be divided into the following three parts based on the contents.1. The method was established for the determination of fungicide mancozeb residue in tomato, cucumber, pear, bean and banana using HS-GC.The mancozeb residue was determined,indirectly via determination of CS2 contents converted in acid system. The study result showed that under the chromatography condiotns such as ECD, DB-1 elastic quartz capillary column (30mxi.d.0.53um), vaporizer temperature 160℃, starting column temperature 40℃, keeping 6min, and then to 60℃with the increasing rate of 5℃/min, detector temperature 260℃, flow rate of nitrogen (99.999%) 3.0mL/min, and splitless ratio 15:1, the average recoveries of mancozeb in tomato, cucumber, pear, bean and banana were in the range of 79.1%～91.7%,79.4%～89.8%,80.3%～88.0%,78.5%～91.5% and 78.4%～89.8%, respectively, at spiking levels from 0.05mg/kg to 1.5 mg/kg, and the relative standard deviation were in the range of 3.0%～10.8%,3.6%～6.9%,3.1%～6.2%, 2.5%～5.1% and 2.1%～4.6%, respectively. 2. The method was established for the determination of ETU residue residue in tomato, cucumber, pear, bean and banana using HPLC. The samples were adjusted to pH=7-9 with ammonia solutioon, adding 80 mL methanol,5 g potassium fluoride,5 g ammonium chloride, sequentially washed three times with 30mL+20mL+20mL petroleum ether, and then concentrated in vacuo for LC analysis. The results showed that under the conditions such as UV detector with variable wavelength, detection wavelength 240nm, inertsil ODS-3 column (4.6mm×250mm,5μm), mobile phase methanol/water (3:97, V/V) with flow rate of 1.0mL/min and injection volume 20μL,the average recoveries of ETU in tomato, cucumber, pear, bean and banana were in the range of 77.9%～88.2%,78.8%～85.8%,79.3%～85.5%,77.4%～82.9% and 76.9%～83.6%, respectively, at spiking levels from 0.05mg/kg to 1.27 mg/kg and the relative standard deviations were in the range of 4.6%～6.8%,5.1%～5.5%, 5.1%～6.3%,4.0%～7.0% and 4.2%～5.9%, respectively.3. Monitoring of mancozeb and ETU residues in five agricultural products such as tomato, cucumber, pear, bean and banana collected from the growing regions and supermarkets of Changchun, Xi' an, Taiyuan, Shanghai, Beijing, Hunan, Henan and Shandong was carried out based on the established methods from July,2009 to May,2010.. The residue monitoring data showed that mancozeb residue in tomato, cucumber, pear, bean and banana was in the range of 0.05mg/kg-0.23 mg/kg, 0.05mg/kg～0.15 mg/kg,0.05 mg/kg～1.36 mg/kg,0.05 mg/kg～0.23 mg/kg and 0.05 mg/kg-0.24mg/kg, respectively, and ETU residue in tomato, cucumber, pear, bean and banana was in the range of 0.05 mg/kg～0.08 mg/kg,<0.05 mg/kg,0.05 mg/kg～0.06 mg/kg,<0.05 mg/kg and 0.05 mg/kg～0.07 mg/kg.