苯乙烯适宜贮存工艺条件研究

测定了贮存时间、阻聚剂TBC(叔丁基邻苯二酚)含量和铁锈量对苯乙烯聚合物和过氧化物含量的影响,通过均匀设计实验考察了苯乙烯聚合物含量与贮存条件的关系.结果表明,当苯乙烯聚合物的质量分数不高于10 mg/kg(优等品指标)时,在贮存温度为20℃条件下,苯乙烯可贮存8~9 d;在30℃时,可贮存5 d;由拟合得到的苯乙烯聚合物含量与贮存条件的关系式解得:贮存温度为18℃,TBC质量分数为13.8 mg/kg,贮存时间为12 d.     

精异丙甲草胺在花生和土壤中的残留

为认识精异丙甲草胺在花生和土壤中的残留消解规律,分别在山东、浙江、河北、陕西进行了精异丙甲草胺在花生和土壤中的残留研究.采用气相色谱法研究了精异丙甲草胺在花生植株、花生壳、花生仁和土壤中的残留量检测方法,样品经二氯甲烷、丙酮提取,中性氧化铝柱净化,ECD检测器检测,精异丙甲草胺在花生植株、花生壳、花生仁和土壤中的添加回收率分别为85.8%～95.7%、85.1%～85.2%、82.5%～90.4%、87.2%～95.4%.相对标准偏差分别为1.9%～4.9%、1.9%～3.9%、1.1%～2.7%、1.3%～2.4%.精异丙甲草胺在土壤中消解速度较快,在土壤中的半衰期山东为10.3 d,浙江为13.0 d,河北为11.7 d,陕西为12.5 d.当精异丙甲草胺施药量分别为864、1 296 g a.i./hm2时,花生收获期土壤、花生植株、花生壳和花生仁中精异丙甲草胺均未检出(＜0.01 mg/kg).     

50%乙草胺水乳剂在花生田残留及消解动态

采用气相色谱配电子捕获检测器(GC-ECD)测定乙草胺在花生田植株、壳、仁及土壤中消解动态和最终残留.花生植株、壳、仁样品用二氯甲烷提取,土壤用甲醇提取,经弗罗里硅土净化,GC-ECD检测,外标法定量.结果表明:当乙草胺添加水平在0.005～1.0 mg/kg范围之间,乙草胺在土壤、植株、花生仁、花生壳中平均回收率为85.3%～96.5%、81.5%～89.0%、85.4%～91.6%、78.5～85.3%.相对标准偏差分别为3.9%～5.0%、2.9%～8.9%、4.9%～12.1%、4.6%～5.7%.乙草胺的最小检出量(LOD)为0.5×10-11g;最低检测质量分数:土壤0.005 mg/kg,植株、花生仁和花生壳为0.01 mg/kg.乙草胺在郑州和长沙土壤中半衰期分别为2.8、3.3 d.     

嘧菌酯在柑橘和土壤中残留动态

研究了嘧菌酯在柑橘和土壤中的残留分析方法及残留动态.柑橘和土壤样品分别用乙腈和丙酮提取,提取液用二氯甲烷液-液分配,硅镁型吸附剂层析净化,气相色谱法测定.结果表明:嘧菌酯添加质量分数为0.01～1.0 mg/kg时,在柑橘和土壤中的回收率分别为87.5%～108.4%、87.1%～94.4%;变异系数分别为4.85%～6.53%、4.37%～7.92%.检测器对嘧荫酯的最小检出量为6 X 10-12g,方法最低检测质量分数为0.01 mg/kg.嘧菌酯在柑橘全果和土壤中的半衰期分别是14.0～14.1 d和44.7～49.2 d.     

土壤和葵花籽中精异丙甲草胺的残留分析

样品经正己烷提取,弗罗里硅土固相萃取小柱净化,气相色谱仪检测.对葵花籽和土壤中的精异丙甲草胺进行不同水平的添加回收率测定,方法的回收率为85.46%～97.76%,变异系数为0.87%～7.81%.精异丙甲草胺的最小检知量为1×10-11g,它在土壤、植株、葵花籽上的最低检出质量分数为0.01 mg/kg.     

3种常用坐果激素主要成分在番茄中的残留

建立了同时分析2,4-滴、氯吡脲、沈农丰产剂2号3种常用坐果激素主要成分2.4-滴、1-(2-氯-4-吡啶基)-3-苯基脲及对氯苯氧乙酸在番茄中的残留分析方法.结果表明:采用超高效美国Phenomenex Kinetex C18柱,以甲醇-水(用醋酸调至pH值3.0)体积比50:50为流动相,流速1.0 mL/min,可以较好地分离3种坐果激素的主要成分.应用该方法,在番茄果实匀浆中添加2,4-滴,添加质量分数在0.10-2.00 mg/kg范围时,回收率为88.72%～91.01%,变异系数为2.63%～4.63%;1-(2氯-4-吡啶基)-3-苯基脲添加质量分数在0.05～2.00 mg/kg范围时,回收率为88.53%～92.41%,变异系数为3.15%～6.73%;对氯苯氧乙酸添加质量分数在0.10～2.00mg/kg范围时,回收率为94.17%～96.29%,变异系数为5.99%～6.78%.     

噻吩磺隆在花生上的残留分析

建立了噻吩磺隆在花生土壤、植株、籽粒中残留的分析方法,即采用甲醇为萃取剂,在超声振荡条件下萃取样品中噻吩磺隆的残留,经氟罗里硅土柱层析净化后,采用反相HPLC-UVD方法对噻吩磺隆在土壤中残留进行定量分析。结果表明,该方法最小检出量(LOD)为4×10-10g,在土壤中最低检出质量分数为0.02mg/kg,在植株和籽粒中最低检出质量分数为0.03mg/kg。噻吩磺隆在土壤、植株和籽粒上的平均回收率分别为83.8%～97.8%、85.2%～96.2%、85.0%～100.2%,相对标准偏差分别为4.2%～10.4%、2.7%～10.1%、4.2%～7.7%,满足残留检测的要求。     

GC/MS/MS法测定油菜籽中异丙甲草胺残留量

采用甲醇和水提取,正己烷萃取,经SPE柱净化,GC/MS/MS测定,建立了油菜籽中异丙甲草胺残留量的GC/MS/MS测定方法.添加质量分数为0.05、0.001 mg/kg,方法平均回收率分别为88.5%和101.7%,相对标准偏差分别为3.0%、6.2%,最低检出质量分数为0.001 mg/kg.     

氟酰胺在稻田环境中的残留行为及安全性评价

[目的]研究氟酰胺在稻田环境中的残留消解情况。[方法]样品采用分散固相萃取-气相色谱法。[结果]氟酰胺在糙米、稻壳、植株、田水和土壤中的平均回收率在87.00%~98.84%之间、标准偏差在0.57%~2.31%之间、变异分数在0.58%~2.44%之间;氟酰胺的最小检出量为1.0×10-11g,在糙米、稻壳、植株、田水和土壤中的最低检测质量分数分别为0.02、0.1、0.05、0.02、0.02 mg/kg。2011—2012年在安徽、湖南和广西试验结果表明:水稻植株中降解半衰期为1.9~5.3 d,稻田水中降解半衰期为1.8~5.1 d,稻田土壤中降解半衰期为4.8~7.7 d;20%氟酰胺·嘧菌酯水分散粒剂以450 g a.i./hm2(1.5倍推荐高剂量)、300 g a.i./hm2(推荐高剂量)施药剂量,施药3、4次,采收间隔期为20、30 d,糙米中氟酰胺的最终残留量最高为0.63 mg/kg(低于2.0 mg/kg)。[结论]中国规定糙米中氟酰胺的最大残留限量值(MRL)2.0 mg/kg,以此依据,20%氟胺·嘧菌酯水分散粒剂用于防治水稻纹枯病,于水稻纹枯病发病初期田间喷雾,最高用药量450 g a.i./hm2,最多施药4次,氟酰胺安全间隔期为20 d。     

异菌脲在油菜籽中残留

建立了异菌脲在油菜籽中的残留分析方法.1×10-3 g/L的异菌脲标准溶液(乙腈溶解,乙腈稀释)在4℃条件下可贮存两个月;油菜籽提取液中的异菌脲在-20℃和4℃条件下可贮存20 d,在25℃条件下贮存不可超过10 d;油菜籽基质巾的异菌脲在4℃、-20℃可贮存20 d,在25℃条件下贮存不可超过10 d.     

酰胺类除草剂甲草胺的微生物降解研究进展

主要介绍了氯乙酰胺类除草剂甲草胺微生物降解的研究现状。甲草胺是一种世界上广泛使用的芽前除草剂,也是普遍存在的危险且难矿化的有机污染物。在被污染的土壤中,有氧条件下的生物降解是其归宿的主要过程。部分土壤微生物能以甲草胺为唯一碳源和能量的方式进行代谢,但共代谢是去除土壤中母体化合物的主要途径。介绍了降解的甲草胺微生物及其主要代谢产物,但因为缺少实验室条件下足够的矿化信息,还不能提出完整的代谢路径。建议继续加强高效降解微生物（群落）的筛选,澄清甲草胺的代谢途径,应用宏基因组学的新技术发掘新的降解基因,并在此基础上探讨了工程微生物（群落）在原位生物修复过程中的作用。     

甲草胺与牛血清白蛋白相互作用的光谱法研究

在模拟人体生理条件下,采用分子光谱法研究了甲草胺与牛血清白蛋白的相互作用.结果发现,甲草胺对牛血清白蛋白的内源荧光有一定的猝灭作用,由Stern-Volmet方程和Van't Hoff等压方程分析和处理实验数据,得到了结合作用的平衡常数、结合反应的热力学参数,确定甲草胺与牛血清白蛋白主要依靠疏水作用力进行结合,该结合反...     

20％甲草胺水乳剂的研制

以粒径测定为主要研究手段,以冷贮[(0±2)℃,14 d]、热贮[(54±2)℃,14 d]稳定性及稀释稳定性(1:200倍)为质量标准,研究了20%甲草胺水乳剂的组成及制备方法,确定最佳配方:Span80/Tween20(质量比为1.2:1)复配乳化剂:5%;正丁醇:3%;丙三醇:5%;67%的甲草胺二甲苯溶液:30%;余量为水.     

气相色谱法测定大豆中氟乐灵、甲草胺和乙草胺农药残留

采用甲醇提取大豆中氟乐灵、甲草胺和乙草胺的农药残留,氟罗里硅土进行柱净化,气相色谱法(μECD检测器)进行测定,3种农药的回收率在73.67%～110.31%之间,变异系数在1.67%～12.95%之间,氟乐灵的最低检出限为0.003mg/kg,甲草胺和乙草胺的最低检出限为0.025mg/kg。     

气相色谱同时测定食用油中甲草胺与腐霉利的残留量

建立了固相萃取-气相色谱-电子捕获检测器（SPE—GC—ECD）同时测定食用油中甲草胺和腐霉利的方法。样品经过乙腈提取、固相萃取柱净化,采用GC—ECD检测,外标法定量。在此条件下,甲草胺的回收率为92．9％-98．9％,相对标准偏差为2．52％-3．24％,腐霉利的回收率为92．8％-99．2％,相对标准偏差在3．42％-6．95％。该方法简便、快速,具有良好的灵敏度、重复性,可适用于食用油中甲草胺和腐霉利的残留检测。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.