毒死蜱在表面活性剂混合体系中的增溶规律及其药效评价

为明确表面活性剂在农药制剂微乳化中的作用和评价农药制剂微乳化对药剂生物效果的影响,通过测定毒死蜱在有机溶剂-表面活性剂混合体系中的最大增溶浓度和在不同表面活性剂 /水微乳体系中的最高浓度,研究了毒死蜱在表面活性剂混合体系中的增溶规律,得到了毒死蜱微乳剂的优化配方,并对30%毒死蜱微乳剂对棉铃虫Helicoverpa armigera的生物活性进行了室内外药效试验。结果表明:毒死蜱在有机溶剂-表面活性剂混合体系中的最大增溶浓度和在有机溶剂-表面活性剂-水微乳体系中的最高浓度分别随体系中表面活性剂浓度和表面活性剂 /水(质量比)的增加而增大,但表现出不同的增溶规律;优化后的毒死蜱微乳体系分散液滴呈球形,流体力学半径约25.9 nm;30%毒死蜱微乳剂与40%毒死蜱乳油对棉铃虫的室内LC50值分别为500和561 mg/L,无显著差异;在相近有效使用剂量下,微乳剂的田间防效并未比乳油显著提高。研究表明,保证制剂中足够的表面活性剂质量分数是农药制剂微乳化形成与稳定的关键,农药制剂微乳化带来的农药有效成分分散度提高并不能显著提高药剂的生物活性。

Solubilization of Chlorpyrifos in the Mixed System of Surfactants and the Bioactivity Evaluation

In order to explain the effect of surfactant in microemulsification of pesticide and evaluate the bioactivity of pesticide microemulsion,the regularity of chlorpyrifos solubilized in the mixed system of surfactants were studied and the optimized formation of chlorpyrifos microemulsion was achieved by chlorpyrifos measurements of the maximum capacity solubilized in the solvent-surfactants system and the maximum concentration dispersed in different surfactants /water microemulsion systems,the bioactivity of chlorpyrifos 300 ME was also investigated on Helicoverpa armigera by laboratory assays and field tests.The results showed the maximum capacity of chlorpyrifos solubilized in the solvent-(surfactants)(systems) and the maximum concentration of chlorpyrifos dispersed in different surfactants/water(microemulsion) systems increased with the concentration of surfactants and the ratio of surfactants /water(m/m)(increased) respectively,but had different curves.The optimized microemulsion is composed of discrete spherical oil droplets which hydromechanical radius is about 25.9 nm.For laboratory assays,the(bioactivity)of chlorpyrifos 300 ME and 400 EC has no significant difference and with LC_(50) values of(500 mg/L) and 561 mg/L respectively.For field tests of chlorpyrifos 300 ME,comparing with 400 EC at the same dosage,the control efficiency is not significant too. It indicated that it was the key to(enough) dosage of surfactant for the formation and stability of pesticide microemulsion and the(bioactivity) of pesticide was not enhanced significantly by the improvement of dispersion by microemulsification of pesticide.