微波消解-石墨炉原子吸收法测定丹参中的铅镉

建立了石墨炉原子吸收法快速测定丹参药材中铅和镉元素含量的方法。利用微波消解样品,选择1.0%磷酸二氢铵和0.2%硝酸镁作为基体改进剂,用石墨炉原子吸收方法完成铅镉元素测定。结果表明,方法线性关系良好,铅和镉的相关系数分别为0.9995和0.9992;检出限分别为0.427μg/L和0.082μg/L;精密度分别为7.44%和10.97%;加标回收率分别为90.5%和104.0%。该方法是一种简便、快捷、准确的分析方法,可为丹参的进一步研究提供科学依据。     

压力消解石墨炉原子吸收法测定小龙虾中铅和镉

目的：建立了压力消解技术进行样品前处理,石墨炉原子吸收法测定小龙虾中铅和镉含量的测定方法。方法：采用硝酸和过氧化氢混合消解液,压力消解法对小龙虾样品进行消解,以磷酸二氢铵作为基体改进剂,氘灯扣背景,石墨炉原子吸收光谱法对样品中铅和镉含量进行测定。结果：铅在0μg/L～50μg/L范围,镉在0μg/L～4.0μg/L范围具有良好的线性,相关系数大于0.999,RSD〈10%。结论：压力消解法具有方法简便、试剂空白低、样品测定准确、易于普及等优点。     

原子吸收分光光度法测定中药材中重金属含量

采用火焰法、石墨炉法,样品消解后直接测定中药材丹参、白芍中重金属铜、铅、镉的含量。结果表明：重金属铜在0～0.8μg/mL、铅在0～80μg/L、镉在0～0.8μg/L范围线性关系良好,相关系数分别为0.995 6、0.996 3、0.999 4;丹参、白芍中所含铜、铅、镉均符合《中国药典》规定。本法简单、快速、灵敏,适用于中药材中微量重金属的测定,结果满意。     

石墨炉原子吸收法测定水中镉和铅

采用石墨炉原子吸收光谱法测定不同水体中的铅,镉的含量.分别试验了不加改进剂、加重铬酸钾、加磷酸二氢铵三种检测方法对测定结果的影响.铅、镉的线性范围分别为0~20 ng/mL、0~15 ng/mL,相关系数r分别为0.999 8、0.999 8,回收率分别为96.5%~101.1%和98%~103.1%,相对标准偏差分别为RSD≤1.026%和RSD≤1.038%。     

石墨炉原子吸收法测定大米中铅、镉、铬3种重金属

通过采用石墨炉原子吸收光谱法对大米中铅、镉和铬3种有害元素含量进行测量。首先对所要进行试验的大米做实验前的预处理,进行消解后,采用石墨炉原子吸收法测定大米中铅、镉和铬3种微量元素含量。结果表明,大米中铅的含量为0.080 mg/kg,镉为0.092 mg/kg,铬为0.062 mg/kg,加标回收率在98%~101%,同一样本平行测定6次的相对标准差小于2.5%。利用石墨炉原子吸收测定大米中的铅、镉和铬的分析方法准确可靠。     

石墨炉原子吸收法测定大米中铅、镉、铬3种重金属

通过采用石墨炉原子吸收光谱法对大米中铅、镉和铬3种有害元素含量进行测量。首先对所要进行试验的大米做实验前的预处理,进行消解后,采用石墨炉原子吸收法测定大米中铅、镉和铬3种微量元素含量。结果表明,大米中铅的含量为0.080 mg/kg,镉为0.092 mg/kg,铬为0.062 mg/kg,加标回收率在98%¹01%,同一样本平行测定6次的相对标准差小于2.5%。利用石墨炉原子吸收测定大米中的铅、镉和铬的分析方法准确可靠。     

石墨炉原子吸收法测定空气中铅和镉

本文建立了采用微孔滤膜采集空气中铅和镉,自动石墨消解仪对滤膜样品进行前处理,石墨炉原子吸收法进行测定的方法。本实验优化了消解液的组合,使滤膜样品消解更完全,当采样体积为300L,铅、镉的最低检出质量浓度分别为0.0001、0.00001mg·m~(-3),加标回收率在92.1%～103.4%之间,6次测定的相对标准偏差均小于4%。该方法具有前处理简单、污染小、检出限低、精密度和准确度较好等优点,适用于大批量环境空气中痕量铅和镉的分析。     

石墨炉原子吸收光谱法测定茶叶中铅

目的：探讨茶叶中铅的检测方法,并用该法测定10个样品（含2个标准样品）的Pb含量。方法：应用基体改进剂,用石墨炉原子吸收光谱法测定茶叶中铅。结果：（1）茶叶中Pb含量的测定适宜条件为：磷酸二氢铵作为基体改进剂,灰化温度700℃,原子化温度2000℃;（2）本法铅的检出限为1.1μg.L-1,回收率为94.0%~108.8%;（3）抽检的市售8种茶叶种有2种铅含量大于5mg.kg-1。结论：该法准确灵敏,回收率好,可满足实际检测要求。     

平台石墨炉原子吸收法测定山楂叶中的痕量镉

以硫脲-EDTA-磷酸二氢铵为基体改进剂,利用平台石墨炉原子吸收法分析了山楂叶中痕量镉的含量,探讨了平台石墨炉测定镉的基体改进剂和仪器条件的影响.方法检出限为0.06 ng/mL,样品检出限为0.19 ng/g.     

土壤中镉测定的影响因素研究

目的:建立石墨消解仪-石墨炉原子吸收光谱测定土壤中的镉分析方法。方法:土壤样品用硝酸-氢氟酸-盐酸-高氯酸混合消解液在石墨消解仪中消解后,加入磷酸氢二铵、硝酸钯、硝酸镁、硝酸钯-硝酸镁混合基体改进剂消除干扰,用石墨炉原子吸收光谱测定。通过对基体改进剂、灰化温度、原子化温度的研究,优化了测定土壤中镉的条件。最终确定以0. 2%硝酸钯为基体改进剂,样品进样为10μL,基体改进剂进样4μL,灰化温度分别为400℃和900℃,原子化温度为1900℃,净化温度为2600℃,氩气作保护气时进行土壤中镉测定的适宜条件。该方法线性良好,相关系数为0. 9995,相对标准偏差3. 46%和1. 15%,方法检出限为0. 012mg/kg。对土壤标样ESS-5和ESS-14的测定结果符合标准值要求。该方法简单,基体干扰少,结果准确,适用于土壤中镉含量的测定。     

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.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

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。