化学蒸气发生-电感耦合等离子体原子发射光谱法测定岩石中的痕量金

使用电感耦合等离子原子发射光谱（ICP-AES）研究了金和硼氢化钠在酸性水溶液中的化学蒸气发生反应的条件,并结合活性炭分离富集技术成功测定了地质标样中的痕量金。研究结果表明,在硼氢化钠和样品溶液流速为2mL／min、废液排放流速为5mL／min的条件下获得最佳蒸气发生条件为：载气流速0．3L／min、蒸气发生反应所用王水酸度1．0mol／L、硼氢化钠浓度为1．2％（m／v）。研究中获得的金化学蒸气进样效率是常规的气动雾化进样效率的5．7倍,检出限是1．0μg／L稍好于气动雾化法;线性范围高端至少可达1500μg／L;线性相关系数是0．9988;1KSD是1．23％。用本法测定国家金地质标样与参考值有很好的吻合。     

一次溶样矿石中金银的测定

目前矿石中金的分析方法主要采用泡塑或活性炭吸附富集,灰化或解析测定金。岩石中银测定主要是酸溶后用原子吸收直接测定。岩石中痕量金一般用石墨炉原子吸收测定,岩石中痕量银一般用发射光谱测定。本文试图在同一个样品处理后直接测定金和银。试验了用甲基异丁基酮萃取富集金,在有机相中测定金,在水相中测定银的方法。方法灵敏度高,快速简单,结果合格率满足分析要求,运用于矿物中0.4μg/g金和1.0μg/g银以上样品分析。     

动力学光度法测定高纯碳酸锂中的痕量铜

基于过氧化氢能氧化桑色素并使之褪色的现象,测定了高纯碳酸锂中痕量铜。该法检出限为0．006μg／mL,线性范围为（0．1～0．6）μg／25mL铜,符合比尔定律,碳酸锂中铜的测定结果与萃取—原子吸收法测定结果相吻合,标准加入回收率为95％～105％。适用于高纯碳酸锂中痕量铜的测定。     

流动顺序注射分离富集-火焰原子吸收光谱法检测污水和废水中Pb Cd Cu Zn

采用D412螯合树脂作为流动顺序注射分离富集微柱填充材料,同火焰原子吸收光谱仪联用,结合所优化的样品酸度,进样速度,淋洗条件和洗脱条件,快速测定污水和废水样品中Pb,Cd,Cu和Zn的含量,样品上柱10 mL富集时,相对标准偏差(RSD)<5.00%,以空白溶液11次测定的标准偏差的3倍求得检出限Pb:1.3μg/L,Cd:0.56μg/L,Cu:0.91μg/L,Zn:0.48μg/L,加标回收率89%-98%。     

痕量亚硝酸盐催化分光光度法测定

介绍使用动力学分光光度法测定痕量(0．003～1．000μg／mL)NO2^-。方法建立在酸性介质中NO2^-对KBrO3和PGR反应的催化效应上。大多数共存离子不干扰测定，特别对于大量NO3^-和NH4^ 。该法成功应用于天然水中痕量NO2^-测定。     

火焰原子吸收光谱法测定涂料中的铅

采用火焰原子吸收光谱法测定涂料中铅的含量，铅在0．5μg／mL～20．0μg／mL范围内具有良好的线性关系。重点讨论了样品的灰化温度、空心阴极灯灯电流对铅含量测定的影响。测定结果RSD≤3．7％，回收率在99．8％，方法简便，结果准确。     

铽-洛美沙星体系荧光光度法测定铽含量

在pH=6．00～6．50条件下,铽(Ⅲ)与洛美沙星反应生成能产生较强Tb^3 特征荧光的配合物。据此反应建立了一种新的测定铽的方法,并对测定条件进行了优化。在最佳实验条件下．测定铽的线性范围为0．012～4．72μg／mL,检测限为1．6ng／mL。对0．236μg／mL Tb^3 标液测定的相对标准偏差2．7％(n=7)。此法用于合成稀土样品的测定,结果令人满意。     

一种新型吸附剂在痕量重金属分析中的应用

以二苯并18-冠-6交联席夫碱型壳聚糖作为新型吸附剂，用石墨炉原子吸收分光光度法测定了经过滤处理后的燃煤烟气中痕量铬、镉和铅的含量。经过滤处理后的燃煤烟气含铬1．42／μg／m3，其中三价铬占54．20％，为0．77μg／m3，镉0．256μg／m3，铅5．30μg/m3。     

聚氨酯泡塑富集-石墨炉原子吸收法测定土壤样品中的痕量金

本文论述了一种聚氨酯泡塑预富集-石墨炉原子吸收法测定土壤化探样品中痕量金的方法。样品经马弗炉700℃灼烧3～4h,再经王水溶解、泡塑振荡吸附、硫脲解脱,以抗坏血酸作基体改进剂消除基体影响,用石墨炉原子吸收进行痕量金的测定。方法测定痕量金的检出限为0.03μg/g。用本方法测定土壤样品中痕量金,回收率为91.6%～102.6%,方法精密度(RSD)为3.45%～7.33%。     

微波消解-火焰原子吸收光谱法测定土壤中的铅、镍、铜

应用微波消解和火焰原子吸收光谱法测定土壤中的铅、镍、铜。考察了土壤的最佳微波消解条件,样品用HNO3-HCl04-HF混合酸经微波消解后,溶解时间由原来的3～5h缩短到3min。以原子吸收光谱法测定土壤中铅、镍、铜。铅、镍、铜的测定波长分别为283．3、232．0、324．8nm;检出限分剐为0．0005、0．0004、0．0001μg／mL;工作曲线的线性范围为0．002～30．00μg／mL,0．001～50．00μg／mL,0．001～6．00μg／mL。方法用于土壤样品的分析,铅、镍、铜的相对标准偏差分别小于0．31％、1．52％、3．29％,回收率在98．00％～102．00％。     

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。