氟虫双酰胺在土壤和白菜中的高效液相色谱分析

采用高效液相色谱法分析了土壤和白菜中的氟虫双酰胺,依次用乙腈和正己烷提取土壤和白菜中的氟虫双酰胺,提取液过弗罗里硅土柱净化,以甲醇-水(体积比1:3)作为流动相,使用C18反相色谱柱和紫外可变波长检测器,用外标法进行分析和定量.土壤中氟虫双酰胺的添加回收率为91.31%～94.80%,变异系数为2.57%～8.33%;白菜中氟虫双酰胺的添加回收率为89.19%～103.15%,变异系数为4.21%～5.43%;氟虫双酰胺在土壤和白菜中的最小检出量均为l×10-10g,最低检出质量分数均为0.003 mg/kg.     

高效液相色谱法分析甘蓝中的氟苯虫酰胺残留

以乙腈为提取溶剂,采用超声波提取甘蓝中残留的氟苯虫酰胺,经QuEChERS预处理,由高效液相色谱(带紫外检测器)检测分析。结果表明:甘蓝中氟苯虫酰胺的添加回收率为81.12%～89.61%,变异系数为1.51%～3.57%,最低检测浓度为0.005 mg/kg。该技术可方便且高效地用于氟苯虫酰胺残留的检测。     

唑虫酰胺在萝卜中的残留及消解动态

[目的]建立唑虫酰胺在萝卜中的高效液相色谱-串联质谱(HPLC-MS/MS)的残留检测分析方法,研究其在萝卜植株、萝卜肉质根和土壤中的消解动态规律。[方法]样品经乙腈提取,PSA、GCB和无水MgSO₄净化,外标法定量,HPLC-MS/MS检测。[结果]萝卜植株、萝卜肉质根和土壤样品中的唑虫酰胺在0.001～1 mg/L范围内线性关系良好(R²>0.999);在0.01、0.1、0.5、10 mg/kg的添加水平下,唑虫酰胺在萝卜植株中的平均回收率为101.8%～105.2%,相对标准偏差为1.6%～5.5%;在0.01、0.1、0.5 mg/kg的添加水平下,唑虫酰胺在萝卜肉质根和土壤中的平均回收率分别为94.2%～97.8%和95.1%～98.7%,相对标准偏差(RSDs)分别为0.9%～3.8%和1.3%～2.2%。唑虫酰胺在萝卜植株和土壤中的半衰期分别为2.5～9.8、5.4～13.6 d,唑虫酰胺在萝卜植株、萝卜肉质根和土壤中的最终残留量分别为0.010～4.366、<0.01～0.092、<0.01～0.170 ...     

S-氰戊菊酯在甘蓝和土壤中的残留分析方法

确立了甘蓝和土壤中S-氰戊菊酯的残留分析方法.样本用丙酮/石油醚提取,中性氧化铝柱层析净化,气相色谱(ECD)测定.在甘蓝和土壤中的平均添加回收率分别为90.7%～98.3%和90.7%～97.0%;变异系数分别为4.8～7.6和3.8～5.0;最低检出浓度分别为0.0025mg/kg和0.00025mg/kg.     

草莓和土壤中啶酰菌胺残留量的高效液相色谱分析

建立了啶酰菌胺在草莓和土壤中的残留分析方法,样品经丙酮提取,二氯甲烷液-液分配,固相萃取小柱净化后,进行高效液相色谱分析.仪器最小检出量为0.1 ng,在草莓和土壤中的最低检出质量分数均为0.02 mg/kg.在草莓中的平均添加回收率为92.3%～94.4%,变异系数为2.64～4.82;在土壤中的平均添加回收率为89.0%～94.3%,变异系数为3.72～5.43.     

稻瘟酰胺在水稻中的残留及消解动态

在长沙、杭州和南宁3地进行田间试验,采用GC-NPD法研究了稻瘟酰胺在稻田生态系统中的动态残留和最终残留的情况.结果表明:稻瘟酰胺在水稻水、土壤和植株中的添加量为0.05～5.00 mg/kg水平时,添加回收率分别为84.27%～97.60%、95.76%～108.67%和91.89%～96.07%,变异系数分别为1.37%～4.75%、0.54%～5.21%和0.87%～1.74%.稻瘟酰胺的最小检出量为1×10-10g,稻米中的最小检出质量分数为0.025 mg/kg.稻瘟酰胺在水稻水、土壤和水稻植株的半衰期分别为6.76～9.35、10.22～14.22、7.13～7.91 d.在使用推荐剂量和高剂量的条件下,收获的稻米中稻瘟酰胺的最终残留量均小于0.50 mg/kg,拟推荐我国稻米中稻瘟酰胺的MRL值为0.5 mg/kg.     

氟草烟在稻田水及土壤中残留分析方法

通过衍生化反应和气相色谱检测来测定稻田水、土壤样品中氟草烟的残留.氟草烟的最小检出量为2.0×10-12g,最低检出质量分数稻田水中为0.001 mg/kg、土壤中为0.002 mg/L.稻田水中氟草烟的平均添加回收率为96.16%～103.20%,变异系数为2.34%～6.97%;土壤中的平均添加回收率为81.35%～94.27%,变异系数为4.26%～6.52%.     

双氧威在土壤及水中残留分析方法

建立了双氧威在土壤及水中的残留分析方法.土壤和水样品分别以丙酮和乙腈提取,高效液相色谱-DAD检测器检测.双氧威的最小检出量为2.0×10-11 g,土壤中的最低检出质量分数为0.03 mg/kg,水中为0.03 mg/L.土壤中双氧威的平均添加回收率为83.5%～100.8%,变异系数为3.2%～6.8%;水中的平均添加回收率为96.2%～100.8%,变异系数为0.7%～2.3%.该方法的准确度、精确度及灵敏度均达到农药残留分析的要求.     

苹果和土壤中溴菌腈残留分析方法

研究并建立了溴菌腈在苹果和土壤中的残留分析方法.苹果和土壤样品分别用丙酮、二氯甲烷和甲苯提取,固相萃取(SPE)净化,气相色谱(GC)测定.溴菌腈的最小检测量为2.0×10-11 g,苹果和土壤中的最低检出质量分数均为0.03 mg/kg.在添加0.05～2.5 mg/kg时,土壤中溴菌腈的平均添加回收率为80.4%～105.1%,变异系数为1.9%～8.4%;苹果中的平均添加回收率为80.6%～96.7%,变异系数为2.0%～4.0%.该方法的准确性、精确性以及灵敏度均达到农药残留分析的要求.     

超高效液相色谱-串联质谱法检测番茄和甘蓝中溴虫氟苯双酰胺的残留

[目的]利用超高效液相色谱-串联质谱建立番茄和甘蓝中溴虫氟苯双酰胺残留量测定的方法。[方法]样品用酸化乙腈提取,N-丙基乙二胺分散吸附剂净化,超高效液相色谱分离,三重四级杆串联质谱检测,外标法定量。[结果]溴虫氟苯双酰胺在0.0002～0.2 mg/L质量浓度范围内呈现出良好的线性关系(r0.999),当添加质量分数为0.01～0.5 mg/kg时,溴虫氟苯双酰胺在番茄中的平均回收率为71.9%～97.3%,相对标准偏差为3.2%～4.1%;在甘蓝中的平均回收率为77.5%～117.5%,相对标准偏差为6.4%～7.6%。[结论]方法的灵敏度、准确度、精密度符合农药残留分析的要求。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。