丙环唑配合物的合成、缓释性能及生物活性研究

Five propiconazole(L) complexes (ML₂Cl₂, M=Zn(Ⅱ), Cu(Ⅱ), Co(Ⅱ); ML₄Cl₂, M=Ni(Ⅱ), Mn(Ⅱ)) were prepared and characterized by elemental analysis and IR. These complexes exhibited favorable controlled release property, it took 40 to 120 hours to release 85% amount of ligand in the water. The toxicity determination to Botrytis cinera, Rhizoctonia cerealis, Gibberella zeae, Fussrium moniliforme and Colletotrichum orbiculare indicated that the fungicidal activities of the complexes were better than that of the ligand except Mn-complex to Rhizoctonia cereali. The EC50 of Zn-propiconazole were 0.045 2～0.144 1 μg·mL^-1, Co- and Ni-propiconazole were 0.066 3～0.210 4 μg·mL^-1 and 0.183 9～0.340 7 μg·mL^-1, respectively, and Mn-propiconazole were only 0.353 6～0.538 0 μg·mL^-1. The growth regulation experiment to wheat seeding by dressing treating indicated that inhibiting activities of the complexes to root length and stem height were weaker than that of the ligand.     

UV-assisted degradation of propiconazole in a TiO2 aqueous suspension: identification of transformation products and the reaction pathway using GC/MS

Photocatalytic degradation of propiconazole, a triazole pesticide, in the presence of titanium dioxide (TiO₂) under ultraviolet (UV) illumination was performed in a batch type photocatalytic reactor. A full factorial experimental design technique was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of propiconazole in a batch photo-reactor using the TiO₂ aqueous suspension. The effects of catalyst concentration (0.15–0.4 gL^?1), initial pH (3–9), initial concentration (5–35 mg L^?1) and light conditions were optimised at a reaction time duration of 90 min by keeping area/volume ratio constant at 0.919 cm² mL^?1. Photocatalytic oxidation of propiconazole showed 85% degradation and 76.57% mineralisation under UV light (365 nm/30 Wm^?2) at pH 6.5, initial concentration 25 mg L^?1 and constant temperature (25 ± 1 °C). The Langmuir–Hinshelwood kinetic model has successfully elucidated the effects of the initial concentration on the degradation of propiconazole and the data obtained are consistent with the available kinetic parameters. The photocatalytic transformation products of propiconazole were identified by using gas chromatography–mass spectrometry (GC/MS). The pathway of degradation obtained from mass spectral analysis shows the breakdown of transformation products into smaller hydrocarbons (m/z 28 and 39).     

Dissipation kinetics,residues and risk assessment of propiconazole and azoxystrobin in ginseng and soil

The combinational fungicide suspension (11.7% propiconazole + 7% azoxystrobin), developed by Syngenta Co., Ltd., is very effective for the control of Alternaria black spot on ginseng. A simple and effective method was developed for determining propiconazole and azoxystrobin residues by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The recoveries of propiconazole ranged from 81.0% to 98.0% with relative standard deviations (RSDs) of 1.23–8.46%, while the recoveries of azoxystrobin ranged from 83.2% to 98.8% with RSDs of 3.29–9.50%. For the dissipation kinetics, the combinational fungicide was sprayed with dosage of 225 g a.i.ha^?1 (1.5 times of recommended dosage) in ginseng and soil at two different locations. The dissipation kinetics followed the first-order kinetics with half-lives of 6.66–13.33 days for propiconazole and 4.92–9.12 days for azoxystrobin. Based on the terminal residues data, the preharvest interval (PHI) could be 35 days at recommended dosage in ginseng. The dietary exposure risk was estimated by risk quotient (RQ). The result showed that the RQ value was obviously lower than RQ = 1, indicating that spraying propiconazole and azoxystrobin in ginseng at recommended dosage was safe for human beings.     

Simultaneous determination and method validation of difenoconazole,propiconazole and pyraclostrobin in pepper and soil by LC–MS/MS in field trial samples from three provinces,China

A liquid chromatography–electrospray ionization tandem mass spectrometry method was developed for simple and accurate detection of the fungicides difenoconazole, propiconazole and pyraclostrobin in peppers and soil. Three fungicides residues were extracted from samples by acetonitrile and cleaned up by dispersive solid‐phase extraction before instrumental analysis. The accuracy and precision of the method were evaluated by conducting an intra‐ and inter‐day recovery experiment. The limits of quantification and detection of difenoconazole, propiconazole and pyraclostrobin in pepper and soil were 0.005 and 0.0015 mg/kg, respectively. The recoveries were investigated by spiking pepper and soil at three levels, and were found to be in the ranges 79.62–103.15% for difenoconazole, 85.94–103.35% for propiconazole and 80.14–97.69% for pyraclostrobin, with relative standard deviations <6.5%. Field experiments were conducted in three locations in China. The half‐lives of difenoconazole, propiconazole and pyraclostrobin were 5.3–11.5 days in peppers and 6.1–32.5 days in soil. At harvest, pepper samples were found to contain difenoconazole, propiconazole and pyraclostrobin well below the maximum residue limits of European Union at the interval of 21 days after last application following the recommended dosage.