分子印迹-基质固相分散萃取-高效液相色谱法测定土壤中4种硫代磷酸酯类农药残留量

建立了一种高效、选择性强的分子印迹-基质固相分散萃取结合高效液相色谱测定土壤中4种硫代磷酸酯类农药(毒死蜱、甲基立枯磷、甲基毒死蜱、甲基对硫磷)残留量的方法;并以甲基立枯磷为模板分子,以甲基丙烯酸(MAA)为功能单体,且n(模板分子)∶n(功能单体)=1∶4,以乙二醇二甲基丙烯酸酯(EDMA)为交联剂,以偶氮二异丁腈为引发剂,采用沉淀印迹聚合方法,合成了甲基立枯磷高分子印迹聚合微球(MIPs);以MIPs作为土壤样品提取液的基质固相分散吸附剂,采用HPLC检测处理后的样品,流动相为V(乙睛)∶V(0.1%乙酸水溶液)=3∶1,流速0.8 m L/min,进样量20μL,检测波长210 nm,采用Agilent Eclipse XDB-C8色谱柱(150 mm×4.6 mm,5μm),柱温25℃。结果显示:MIPs对甲基立枯磷有特异性吸附,对其结构相似物毒死蜱、甲基对硫磷和甲基毒死蜱也具有一定的吸附性能;在0.01~5.0 mg/kg范围内,各药剂的质量浓度与相应的峰面积间呈良好的线性关系,相关系数r为0.997 5~0.999 8;4种硫代磷酸酯类有机磷杀虫剂的检出限(LOD)为0.452~1.226μg/kg;添加回收率为76%~96%,相对标准偏差(RSD)为2.8%~7.3%。该方法可用于土壤中硫代磷酸酯类有机磷杀虫剂残留量的测定。     

有机磷农药残留分子印迹聚合物研究现状与展望

为解决有机磷农药在土壤及水体中的残留污染问题,分子印迹技术在该类农药残留检测中的应用研究已得到迅速发展。文章就有机磷农药分子印迹聚合物 (molecularly imprinted polymers,MIPs) 的研究背景、分子印迹技术基本原理及分类、计算化学在筛选优化虚拟模板及功能单体中的应用,以及有机磷农药残留MIPs的制备与应用研究等内容进行了综述。MIPs因具有结构可预测、特异识别和应用普遍的特性,可广泛用于光学传感、化学传感、电化学传感、光电传感、质量敏感传感、仿生催化及样品前处理等众多领域。可通过Discovery Studio、HyperChem及Gaussian 3种分子模拟软件对 (虚拟) 模板、功能单体以及二者所形成的加合物进行计算模拟以获得最低能量的优势构象,通过计算加合物的结合能来优化筛选 (虚拟) 模板和功能单体。将计算化学与实验研究相结合,相信在未来几年,有机磷农药残留MIPs有可能在原位显色传感、农产品农药残留高通量筛查及计算机自动化检测等领域得到长足发展。     

利用分子印迹固相萃取技术净化韭菜中残留的敌百虫

以敌百虫为模板,以 α -甲基丙烯酸(MAA)为单体、偶氮二异庚腈(ABVN)为引发剂、三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂以及乙腈为溶剂,在 n (敌百虫) : n (MAA) : n (TRIM)=1 :8 :40的条件下制备了敌百虫的分子印迹聚合物(敌百虫-MIP)。该MIP对敌百虫的吸附率是非印迹聚合物(NIP)的2.4倍,印迹效果良好。敌百虫-MIP-固相萃取柱对韭菜样品中杂质的去除效果明显好于C18固相萃取柱。在1 ~0.05 mg/kg添加水平内,韭菜中敌百虫的添加回收率在92.7% ~84.7%之间,相对标准偏差( RSD )在8.5% ~4.3%之间,检测限(LOD)为0.01 mg/kg。     

西草净分子印迹电化学传感器的制备及应用

为了解决大型检测仪器在检测过程中的局限性，利用分子印迹技术，以西草净为模板分子、甲基丙烯酸为功能单体，采用原位引发聚合法，在玻碳电极表面进行热聚合成膜，制备出西草净分子印迹电化学传感器，并将其用于样品中西草净含量的检测。采用循环伏安法 (CV) 对印迹电极的电化学性能进行了测试，并使用超高效液相色谱-串联质谱法 (UPLC-MS/MS) 对测试结果进行验证。结果表明:在滴涂量为10 μL、60 ℃下热聚合制备出的西草净电化学传感器 (SMT-MIP/GCE) 具有良好的选择性、重复性和稳定性，其线性范围为0.5~1 μmol/L(1) 和2~30 μmol/L(2)，对应的线性关系分别为I₁ = ?3.33 c+39.03，I₂= ?0.75 c+35.52，相关系数分别为r₁ = 0.985，r₂ = 0.997，检出限 (LOD) 分别为LOD₁ = 0.13 μmol/L和LOD₂ = 0.89 μmol/L。将所建立的西草净分子印迹电化学检测方法用于烟叶添加样品提取液中西草净的检测，该印迹电极能够在8 min内完成对烟叶添加样品提取液中西草净的吸附，回收率为76%~88%，相对标准偏差为2.7%~7.6%，该方法能够初步满足烟草中西草净快速检测的需求。     

5种化学除草剂防除狼毒大戟药效试验

狼毒大戟(Euphorbia fischeriana)在草原上的大量分布严重影响草原生态和草地生产力,为筛选出最适宜防除狼毒大戟的除草剂、探索最佳防治时间和最佳施药量,通过对5种化学除草剂设置不同的施药量,在不同的施药时间对狼毒大戟进行防治试验。结果表明,48%三氯吡氧乙酸乳油防治效果最佳,防效可达99%,最佳施药时间为盛花期,最佳施药量为4.2 L/hm2。20%氯氟吡氧乙酸乳油、72%2,4-滴二甲胺盐水剂、48%麦草畏水剂、75%二氯吡啶酸可溶性粒剂防效均在30%左右,不适用于狼毒大戟的防治。     

N-{5-[1-(2,4-二氯苯氧)乙基]-1,3,4-噻二唑-2-基}-N′-芳酰基硫脲的合成及其生物活性

通过2-氨基-5-[1-(2,4-二氯苯氧)乙基]-1,3,4-噻二唑与芳酰基异硫氰酸酯反应,合成了12个新的芳酰基硫脲,采用核磁共振氢谱、红外光谱和元素分析确证了它们的结构。初步的生物活性测定试验表明,部分化合物具有良好的植物生长调节活性,其中化合物2 c、2 j具有较好的生长素活性,其促进率分别为26.6%与26.9%,但不及对照β-吲哚乙酸。     

新农药O,O-二甲基-1-(2,4-二氯苯氧基乙酰氧基)乙基膦酸酯的水解

研究了新型除草剂O,O-二甲基-1-(2,4-二氯苯氧基乙酰氧基)乙基膦酸酯(HW-02)在不同pH及温度下的水解动态,并初步探讨了其水解机理。结果表明:25℃时,HW-02在pH 5、7和9的缓冲液中的水解半衰期分别为191.3、6.2和0.2 h,即其在碱性环境中的水解速率较在中性和酸性中的快;在pH 7的缓冲液中,25、35、45和55℃下的水解半衰期分别为6.1、4.2、1.8和0.7 h,温 度效应系数(Q)为1.46～2.64,即其水解速率随温度的升高而加快;HW-02水解反应的活化能与温度之间无明显相关性,且其平均活化能和活化焓均较小,分别为60.51 kJ/mol和57.70 kJ/mol,而其活化熵的绝对值却随温度的升高而增加,表现出显著的相关性,其平均活化熵为-81.00 kJ/(mol·K),表明其水解主要由反应的活化熵驱动。采用气相色谱-质谱联用(GC-MS)技术对HW-02的水解产物进行了分离和鉴定,初步确定其水解产物主要为2,4-二氯苯氧基乙酸,推测其主要水解途径为酯键断裂。     

2, 4-滴丁脂对作物药害特点及其防范措施

1 2,4-滴丁脂的作用特点2,4-滴丁脂(2,4-D butylate)是属苯氧酸类选择性除草剂,在双子叶植物体内具有很强的内吸传导作用,常用于防治禾本科作物中的双子叶植物阔叶杂草。其杀草机制:主要是对不同部位的植物核酸和蛋白质产生不同的影响,在植物顶端抑制核酸代谢和蛋白质的合成,使     

分子印迹传感器技术在农药检测中的应用

介绍了非共价型分子印迹聚合物的聚合过程及应用;综述了近年来分子印迹传感器在不同种类农药检测中的研究进展。目前,印迹传感器技术可用于莠去津、敌草净、2,4-滴、草甘膦、对硫磷、氯霉素等农药的检测,对大部分农药检测限可达μmol/L级。随着分子印迹和微电子技术的发展,印迹传感器技术作为一种新的农药检测方法,具有广阔的发展前景。     

使它隆防除麦田阔叶杂草试验初报

使它隆是美国陶氏化学公司新近开发的除草剂,化学名称为4-氨基-3,5-二氯-6-氟-2-吡啶氧乙酸,通用名fluroxypyr,商品名starane,又名氟氧吡啶,是一种内吸传导型除草剂。现将本站1988年进行的使它隆防除麦田阔叶杂草试验初步结果报告如下。材料和方法 (一)供试药剂     

Spray application factors and plant growth regulator performance: II. Foliar uptake of gibberellic acid and 2,4-D

Effects of droplet size and carrier volume on foliar uptake and translocation of gibberellic acid (GA₃) and 2,4-D were investigated. Simulated spray droplets were applied to primary leaves of 10-day-old Phaseolus vulgaris (cv Nerina) in droplet sizes and carrier volumes ranging from 0.5 to 10 μl and 10 to 200 μl per leaf, respectively. Doses of GA₃ (2 μg per leaf) and 2,4-D (100 μg per leaf) were held constant. Total uptake of GA₃ approached a penetration equilibrium within 24 h after application, but uptake of 2,4-D continued to increase. Decreasing droplet size and/or increasing carrier volume increased GA₃ and 2,4-D uptake. Translocation to stem and roots was positively related to total uptake. A positive linear relationship between the logarithm of the total droplet/leaf surface interface area and 2,4-D uptake or translocation was found, but for GA₃ this relationship was quadratic. Potential mechanisms of the effects of spray application factors on foliar uptake are discussed. © 1999 Society of Chemical Industry     

Adsorption–desorption of 2,4-D by hydroxy aluminium montmorillonite complexes

Adsorption–desorption characteristics of 2,4-dichlorophenoxyacetic acid (2,4-D) on pure montmorillonite and synthetic chlorite-like complexes [Al(OH)_x-montmorillonite complexes, obtained by coating montmorillonite surfaces with different amounts of Al(OH)_x] were investigated. The equilibrium adsorption of 2,4-D was described by both Langmuir and Freundlich type isotherms. The extent of adsorption as well as the type of interaction between adsorbate and adsorbent was affected by the nature of incubation buffer and the charge characteristics of supports. At pH 5·6 and in acetate buffer, 2,4-D was negatively adsorbed by montmorillonite and herbicide adsorption capacity increased with increasing amounts of Al(OH)_x species loaded on montmorillonite surfaces. When adsorption experiments were performed at the same pH but in phosphate buffer, strong reductions of both the amount of adsorbed pesticide and its affinity for the adsorbents were measured. Evidently, phosphate anions competed strongly with 2,4-D anions for the sorption site on chlorite-like complexes. Furthermore, desorption tests revealed that a large amount (about 60%) of the pesticide was firmly bound to the clay and was not removed even after repeated washings or 24 h exposure to desorption solution. Both electrostatic interactions between the negative COO^- moieties of 2,4-D and the positive sites on clays, and ligand exchanges of COO^- groups with -OH or water at the clay surface were probably involved in the adsorption process. ©1997 SCI     

STUDIEN ZUR VERTEILUNG VON 14C-MARKIERTEM 2,4-D IN VERSCHIEDEN EMPFINDLICHEN UNKRÄUTERN

Studies of the absorption and translocation of ¹⁴C-2,4-D in Chenopodium album L., Galinsoga parviflora Cav., Datura stramonium L. and Galium aparine L. in relation to their susceptibility gave the following results: In G aparine (resistant) there was little transport of 2,4-D applied to the leaves, and a probable relationship between resistance and the immediate binding of the 2,4-D in the treated leaf. D. stramonium (relatively resistant) transported 2,4-D in considerable amounts alter uptake through the leaf, while C. album (very susceptible) and G. parviflora (susceptible) were intermediate in respect of 2,4-D translocation. No relationship between susceptibility of these four species and 2,4-D uptake and translocation from the leaves could be established. After application to the root systems of the four species, 2,4-D was taken up and translocated in the shoot to varying extents. In G. aparine much 2,4-D was taken up and translocated. In contrast to leaf application, the herbicide was not immediately converted into a strongly-held immobile form. In C. album, G. parviflora and D. stramonium, however, no 2,4-D was translocated in the shoot. There was thus no correlation between susceptibility and shoot transport of 2,4-D in the four species studied. Distribution du 2,4-D marqué au ¹⁴C dans des espèces de mauvaises herbes présentant des sensibilités diverses     

In-vivo effects of 2,4-D and atrazine on cytochrome P-450 and insecticide toxicity in southern armyworm (Spodoptera eridania) larvae

After feeding 2,4-D or atrazine in a diet to southern armyworm (Spodoptera eridania Cram.) larvae for three days, the effect on total content and activities of cytochrome P450 and on insecticide toxicity were determined. Both 2,4-D and atrazine induced cytochrome P450-catalyzed aldrin epoxidation (AE) and methoxyresorufin O-demethylatin (MROD). The 2,4-D was a more potent inducer for total cytochrome P450 content, whereas atrazine disproportionately increased AE. Both compounds increased MROD significantly. The apparent kinetic characteristics of AE indicates that 2,4-D and atrazine induced similar P450 isozymes (K_m 8.78 and 7.80 μM, respectively), which may differ from the constitutive isozyme (K_m 3.14 μM). The 2,4-D-induced cytochrome P450 contributed to decreased carbaryl and permethrin toxicity, whereas the atrazine-induced cytochrome P450 caused decreased parathion and permethrin toxicity. The carbaryl toxicity correlated directly with 2,4-D-induced total P450 content and activities but not with atrazine-induced changes. The 2,4-D and atrazine also induced nonspecific esterase activity which may contribute to permethrin detoxification.     

Adsorption,Desorption and Mobility of Four Commonly Used Pesticides in Malaysian Agricultural Soils

Working with Malaysian agricultural soils, high Freundlich adsorption distribution coefficients (K_ads(f)) were observed for paraquat (28·7 and 1419) and glyphosate (83·8 and 417) and lower values for 2,4-D (0·57 and 5·26) and lindane (2·65 and 14·1) in a sandy loam and a muck soil, respectively. Desorption of 2,4-D and lindane from the muck soil occurred. The adsorption of the pesticides was not affected by temperature (20°C/30°C), pH or addition of the pesticides as a mixture. Leaching of 2,4-D and lindane was evident under a high water influx (200 mm). Comparable results in the leaching of 2,4-D were observed between laboratory studies and a VARLEACH model prediction. © 1997 SCI.     

Spray application factors and plant growth regulator performance: I. Bioassays and biological response

Bioassays were adapted to investigate effects of droplet size and carrier volume on performance of daminozide, gibberellic acid (GA₃) and 2,4-D using Phaseolus vulgaris L. as a model system. Response to plant growth regulators was indexed by inhibition (daminozide), promotion of internode elongation (GA₃) or ethylene production (2,4-D). Elongation of first plus second internodes above primary leaves was evaluated 14 days after treatment of primary leaves, while ethylene production was determined from head-space samples of incubated leaves 24 h after treatment. Daminozide inhibition of internode elongation was related to decreased cell size and number in pith and epidermis (range 49–70% of the untreated control). GA₃ increased cell size and number in both tissues 2·3- to 4·8-fold. Responsiveness to daminozide and 2,4-D markedly decreased as seedling age increased from 8 to 12 days, but responsiveness to GA₃ increased. Decreasing droplet size (10–0·5 μl) and increasing carrier volume (10–200 μl per leaf) at constant dose of daminozide (100 μg per leaf) and 2,4-D (100 μg per leaf) significantly increased performance, but had little effect on performance of GA₃ (2 μg per leaf). Effects of application factors on performance were related to their effects on the interface area between droplets and leaf surface. Significant positive linear relationships were obtained between plant response and the logarithm of the droplet/leaf interface area for all growth regulators. © 1998 Society of Chemical Industry     

Effects of certain herbicides on the oxidative decarboxylation of tryptophan by peroxidase

Non-enzymic and peroxidase-catalysed oxidative decarboxylations of tryptophan (TPP) were studied. The in-vitro rate of enzymic reaction was affected by various herbicides at low concentrations (10^?5?10^?4_M): dinoseb, 2,4-D, dichlobenil and benazolin acted as inhibitors; on the other hand, chlorpropham, bromacil, diphenamid and 4-ethylamino-6-isopropylamino-1,3,5-triazin-2-ol (hydroxyatrazine) were stimulatory. The results of in-vivo experiments showed that chlorpropham and 2,4-D changed the activity of peroxidase from Brassica germinated seeds in vivo, as they do in vttro. Determinations of consumed TPP were carried out either by spectro-photometry or by chromatography.