The Research On Degradation Dynamics Of Tebuconazole In Soybean And Soil By Gas Chromatography Analyzing Method

The residue dynamics of tebuconazole was studied in soybean, plant and soil. The samples were extracted with acetone, and cleaned up with petroleum ether by liquid-liquid partition. They were cleaned up by glass column chromatography with Florisil and determined by gas chromatograph with nitrogen-phosphorus detection (NPD) and GC-MS respectively.The result of GC-NPD:The average recoveries of tebuconazole in soybean, plant and soil were 97.0-101.9%,94.3-99.3% and 96.4-99.4% respectively at the spiking levels of 0.02 to 1.00 mg·kg-1. The corresponding relative standard deviations were 7.0-9.4%,13.6-14.4% and 6.0-14.4%, respectively. The lowest detection limit of instrument for tebuconazole was 1×10-10 g. The limit of quantitation was 0.01 mg·kg-1. The described method is simple, sensitive and accurate.The result of GC-MS:The average recoveries of tebuconazole in soybean, plant and soil were 99.0%-103.6%,96.9%-105.3% and 99.0%-101.6% respectively at the spiking levels of 0.02 to 1.00 mg·kg-1.The corresponding relative standard deviations were 5.6-7.0%,5.4-7.5% and 2.5-6.7%, respectively. The lowest detection limit of instrument for tebuconazole was 5×10-10g. The limit of quantitation was 0.1 mg·kg-1. The described method is simple, sensitive and accurate.When high dosage 193g a.i.·hm^-2 water solution of 25% tebuconazole EW were applied in soybean, plant and soil, residues of tebuconazole in plant were 3.889^-20.252 mg·kg-1, in soil was 0.409-0.864 mg·kg-1 on hour respectively, the half-life of tebuconazole was 0.6^-2.0d on plant,0.8-9.5d on soil respectively, the degradation rate was more than 90% on the corn after three days. The results showed that tebuconazole is easy to degrade in soybean and soil.The final residual concentration of tebuconazole in soybean and soil was determined. The results of two years showed that when 193 g a.i.·hm^-2 water solution of tebuconazole EW was applied in soybean and field, the residual concentration in plant and soil was detected respectively, but the residual concentration in soybean was not detected. The result supports that the residual concentration was no relation with applying dosage. When they were increased of applying dosage, there was no accumulation of tebuconazole residues in soil.Through comparing and analyzing the GC-NPD and GC-MS analytical technologies, it has been studied of two kinds of superiority.