异噁草酮的合成研究

以氯代特戊酰氯、硫酸羟胺和邻氯氯苄为主要原料合成高效除草剂异噁草酮。采用过饱和的氢氧化钠浆料,提高了反应速度和异噁草酮的收率。反应总收率≥84%。     

Validation of pH-Metric Technique for Measurement of pKa and log Pow of Ionizable Herbicides

Abstract

Knowing the values of pK_a and partition coefficients between 1-octanol and water (P_ow) of ionizable herbicides helps us to understand the movement of these compounds in plants and soil. However, shake-flask and high-pressure liquid chromatography (HPLC) techniques. though valuable for measurement of log P_ow of herbicide molecules that do not ionize in aqueous solution, are difficult to use for ionizable molecules; this is especially so for molecules that form ion pairs having appreciable log P_ow values, those with multiple ionizations and for bases with high pK_a values. Our aim in this study was to validate the use of the pH-metric technique (based on potentiometric titration) for measurements of pK_a and log P_ow of ionizable standard substances and herbicides. The values obtained show good correlation with results from other techniques, including shake-flask and HPLC. The OECD Guideline for Testing of Chemicals 117, adopted 30th March 1989, describes the use of HPLC for the measurement of log P_ow. It is hoped that these studies and further testing of this technique will permit it to be included in these OECD guidelines.     

HPLC法拆分高效盖草能乳油中吡氟氯禾灵的光学异构体

建立了高效盖草能乳油中有效成分精吡氟氯禾灵的快速、准确的高效液相色谱分析方法;在流动相为正已烷-异丙醇（体积比70：30）,流速1.0mL/min,检测波长为280nm,柱温为25℃时,高效盖草能乳油中吡氟氯禾灵的光学异构体在Chiralcel OK柱得到很好分离;方法的标准偏差和相对标准偏差分别为0.46g/L和0.43%     

气相色谱化学电离二级质谱法测定土壤中16种三嗪类除草剂的残留

建立了气相色谱化学电离二级质谱法(GC-CI-MS/MS)同时测定土壤中16种三嗪类除草剂多残留量的方法,测定16种三嗪类除草剂仅需12min。样品采用乙腈与盐酸混合溶液,加入氯化钠超声波辅助提取,离心后,乙腈层经过国产石墨化炭黑(GCB)柱净化,流出液浓缩后环己烷定容,GC-MS/MS测定。研究比较了在不同进样溶剂下的化合物响应和不同填料固相萃取(SPE)柱的萃取净化效果,结果表明,环己烷作为进样溶剂效果最好,国产GCB和C18-SPE柱的回收率较好,同时国产GCB对色素的净化效果好,替代进口SPE柱,可以节约实验成本。16种三嗪类除草剂在0.05(0.1)～8.0mg/L范围内线性良好,相关系数在0.9952～0.9999之间;在0.005～0.02μg/g添加水平范围内,平均添加回收率在91.41%～114.12%之间;相对标准偏差在1.1%～16.8%之间。本方法中16种三嗪类除草剂在土壤中的检出限均低于0.005μg/g。     

Improved Adsorption of the Toxic Herbicide Diuron Using Activated Carbon Obtained from Residual Cassava Biomass (Manihot esculenta)

The production and consumption of cassava (Manihot esculenta) occur in several places worldwide, producing large volumes of waste, mostly in the form of bark. This study sought to bring a new purpose to this biomass through producing activated carbon to use as an adsorbent to remove the herbicide Diuron from water. It was observed that the carbon contains the functional groups of methyl, carbonyl, and hydroxyl in a strongly amorphous structure. The activated carbon had a surface area of 613.7 m² g⁻¹, a pore volume of 0.337 cm³ g⁻¹, and a pore diameter of 1.18 nm. The Freundlich model was found to best describe the experimental data. It was observed that an increase in temperature favored adsorption, reaching a maximum experimental capacity of 222 mg g⁻¹ at 328 K. The thermodynamic parameters showed that the adsorption was spontaneous, favorable, and endothermic. The enthalpy of adsorption magnitude was consistent with physical adsorption. Equilibrium was attained within 120 min. The linear driving force (LDF) model provided a strong statistical match to the kinetic curves. Diffusivity (D_s) and the model coefficient (K_LDF) both increased with a rise in herbicide concentration. The adsorbent removed up to 68% of pollutants in a simulated effluent containing different herbicides. Activated carbon with zinc chloride (ZnCl2), produced from leftover cassava husks, was shown to be a viable alternative as an adsorbent for the treatment of effluents containing not only the herbicide Diuron but also a mixture of other herbicides.     

Sonochemical construction of hierarchical strontium doped lanthanum trisulfide electrocatalyst: An efficient electrode for highly sensitive detection of ecological pollutant in food and water

Herbicides are used constantly in agriculture to enhance productivity across the globe. This herbicide monitoring requires utmost importance since its high dose leads to ecological imbalance and a negative impact on the environment. Moreover, a quantification of toxic herbicide is one of the important problems in the food analysis. In this work, deals with the development of a simple, and facile one-pot sonochemical synthesis of strontium doped La₂S₃ (Sr@La₂S₃). Morphological and structural characterization confirms the doping of Sr@La₂S₃ to generate a hierarchical layered structure. The electrochemical performance of modified with rotating disk electrode (RDE) using Sr@La₂S₃ composite is high, compared to La₂S₃ and bare electrodes towards the quantitative detection of mesotrione (MTO) in phosphate buffer. Sr@La₂S₃/RDE showed good sensitivity for MTO detection and it exhibit a range of 0.01–307.01 μM and limit of detection of 2.4 nM. Besides, the selectivity of fabricated electrode is high as it can electrochemically reduce MTO particularly, even in the presence of other chemicals, biological molecules and inorganic ions. The repeatability of MTO detection is high even after 30 days with a lower RSD values. Hence, simple fabrication of Sr@La₂S₃/RDE could be a novel electrode for the sensitive, selective, and reproducible determination of herbicides in real-time applications.