微波消解样品-火焰原子吸收光谱法测定白花蛇舌草中微量元素

提出了火焰原子吸收光谱法测定白花蛇舌草中微量铁、铜、锌、镁、钙、锰的含量.采用浓硝酸、高氯酸和过氧化氢(体积比8:1:2)混合液对样品进行消解.测定钙、镁时,加入二氯化锶,以消除共存物的干扰.用6种元素的标准溶液制作了各自的标准曲线,所得线性回归方程的相关系数在0.986 9～0.999 6之间.在白花蛇舌草样品的基础上,加入一定量6种元素的标准溶液作回收率试验,得回收率在98%～101%之间.     

沉淀分离金-电感耦合等离子体原子发射光谱法测定镀金溶液中铁、钴、镍、铜、银、铅

提出了用电感耦合等离子体原子发射光谱法测定镀金槽液中铁、钴、镍、银、铜及铅6元素,镀液中的金预先用硫酸及过氧化氢沉淀法予以分离,对试样的处理,沉淀分离,AES测定及仪器工作参数等分析条件作了试验并予以优化,测得上述6元素的检出限(3S)在0.002 4～0.067 mg·L-1之间.按所提出方法分析了两种低氰镀金槽液样品,并在此基础上加入不同量的6元素标准溶液后进行回收试验,所得回收率在83.0%～120.0%之间,相应测定值的相对标准偏差(n=5)在2.36%～11.839,6之问.     

微波消解试样-火焰原子吸收光谱法测定粉煤灰中重金属元素

提出了火焰原子吸收光谱法测定粉煤灰中微量铅、铬,镍、铜、锌和锰含量的方法。采用硝酸和氢氟酸(体积比8比1)混合酸对试样进行消解,再加入硼酸溶解铝、钙、镁所生成的难溶氟化物。用6种元素的标准溶液制作了各自的标准曲线,所得线性回归方程的相关系数在0.999 1~1.000 0之间。在粉煤灰试样的基础上,加入一定量6种元素的标准溶液作回收试验,得到回收率在94.9%~102.4%之间。     

气相色谱法测定蔬菜中22种多氯联苯残留量

用丙酮及正己烷(1+1)混合溶剂在ASE 200型微波提取仪中提取蔬菜样品,所得提取液经无水硫酸钠脱水后蒸缩至近干,用正己烷熔解残渣,所得溶液通过弗罗里硅柱纯化。用正己烷淋洗弗罗里硅层析柱,收集合并淋出液,蒸缩后定容为2.0 mL,供气相色谱测定。所测定的22种多氯联苯的质量浓度与各自对应的峰面积在一定范围内呈线性关系,由各线性回归方程求得的相关系数均在0.999以上。以大白菜样品作基体,加入22种多氯联苯单体的混合标准溶液作方法的回收试验,测得回收率在84.0%～99.0%之间。在一种浓度的混合标准溶液水平上进行6次测定,求得相对标准偏差在0.90%～2.69%之间。     

微波消解样品-火焰原子吸收光谱法测定人发中10种微量元素

0.200 0g人发试样经5.0mL硝酸和1.0mL过氧化氢消解,用火焰原子吸收光谱法测定其中钙、铁、锌、锰、铜、铅、镉、钴和镍的含量,用氢化物发生-火焰原子吸收光谱法测定硒的含量。测定钙时,加入镧溶液,以消除共存物的干扰。用10种元素的标准溶液制作了各自的标准曲线,所得线性回归方程的相关系数在0.998 5～0.999 9之间,检出限(3σ)为0.002～0.009mg.L-1之间。以人发样品为基底,加入一定量10种元素的标准溶液做回收试验,得到回收率在95.6%～103.5%之间。     

微波消解-电感耦合等离子体质谱法探讨青海不同产地枸杞中微量元素的差异

采集了生长于青海省6个不同地区的枸杞样品150个,并制取分析用样品。每个样品称取约0.5g置于石英管中,加入水1mL和硝酸4mL,按程序进行微波消解,所得溶液在电感耦合等离子体质谱工作条件下测定其中24种微量元素(钾、钠、钙、镁、铁、锌、铜、锰、钴、镍、铅、砷、镉、铬、硒、钼、锑、锶、锡、镨、钆、镝、汞、铽)。用各元素的标准溶液绘制标准曲线。测得各元素的检出限(3s)在0.008～10μg·L-1之间。选用都兰地区的样品进行精密度和回收试验,24种元素测定值的相对标准偏差(n=6)在0.95%～6.6%之间。在回收试验中,称取4份样品,其中1份样品的测定值为本底值,其余3份样品中分别加入3个浓度水平的15种元素的标准溶液,按方法测得各元素的含量,计算得回收率在85.0%～107%之间。运用仪器自带的MPP软件对所有样品所测得的24种元素的分析数据进行主成分分析和聚类分析。结果表明:钠、镁、钙、锰、铁、钴、镍、铜、锌、镉、铅、钼、镨等元素含量在不同个体样品中差异较明显;来自德令哈与格尔木的样品区分度较好;都兰、乌兰和诺木洪的样品散布比较广,样品间的差异不明显;在青海省各地产出的枸杞的24种元素中,钆与镝存在高度相关。     

电感耦合等离子体原子发射光谱法测定镍基高温合金中铬、钛、铌、铝、铁、硼的含量

在对各元素的分析谱线的选择及基体元素镍对相关元素测定的干扰作了系统研究的基础上,提出用电感耦合等离子体原子发射光谱法(ICP-AES)同时测定镍基高温合金中铬、钛、铌、铝、铁及硼6种合金元素的方法。上述6种元素的检出限(3s/k)在0.006 9~0.13 mg.L-1范围内。取GH 33镍基高温标准样品按所提出方法分析,测定值与标准值相互一致,测得相对标准偏差值(n=10)均小于1.5%。在基体镍溶液中加入各被测元素的标准溶液做回收试验,上述6种元素的回收率在98.3%~101.0%之间。为对此方法的准确性作进一步考核,对GH 4145高温镍基合金样品进行分析,各元素的测定值与国家标准方法的测定值相符合。     

火焰原子吸收光谱法测定土壤中金属元素

土壤样品用硝酸-氢氟酸-高氯酸(5+5+3)混合酸消解后,采用火焰原子吸收光谱法分别测定了试样溶液中铁、锰、铜、锌、铅、镉和镍的含量。因消解过程中加入了氢氟酸,大部分硅生成四氟化硅气体除去,可在此溶液中直接测定其中铁、锰、铜、锌及镍的量。考虑到SiO_3~(2-)、Ti(Ⅳ)及Al~(3+)对锰测定有负干扰,加入一定量的氯化钙溶液作为释放剂消除其干扰。如试样含铁量较高,须加入硝酸镧溶液作释放剂以克服其对锌测定的干扰。测定铅及镉时须加入碘化钾溶液使之生成碘化物络阴离子后,用4-甲基-2-戊酮作溶剂进行萃取分离,随后在有机相中测定铅与镉的含量。用7种元素的标准溶液制作了各自的标准曲线,所得线性回归方程的相关系数在0.999 2～0.9996之间。以土壤样品为基体,加入一定量7种元素的标准溶液做回收试验,得到回收率在96.8%～99.9%之间,相对标准偏差(n=6)在0.9%～2.0%之间。     

微波消解-电感耦合等离子体原子发射光谱法测定催干剂中金属元素含量

应用电感耦合等离子体原子发射光谱法(ICP-AES)测定了不同种类催干剂中9种金属元素,即钴、锰、铅、钙、锌、钒、锆、镧和铈。样品置于聚四氟乙烯溶样罐中加入浓硝酸及高氯酸,盖紧罐盖后按预设程序分两步进行微波加热,加压消解,所得溶液稀释至一定体积供ICP-AES分析。对上述元素的谱线中选择合适的谱线作分析线,达到了9元素的同时测定。同混合标准溶液制备各元素的工作曲线,其线性范围均在100.0 mg·L~(-1)以内。以一催干剂样品为基体,用标准加入法作回收试验,测得回收率在93.8%～109.9%之间,测定值的相对标准偏差(n=6)在0.11%～1.56%之间。不同来源的5个催干剂样品的分析结果表明所测得的金属元素的类别和含量显著差异。试验还证实所提出的方法具有操作快速、简单、方便,适合应用于日常分析工作。     

火焰原子吸收光谱法测定温里类中草药中痕量元素

应用火焰原子吸收光谱法测定了6种温里类中草药(即香附子、干姜、肉桂、细辛、高良姜及小茴香)中4种痕量元素铜、铁、锌及锰的含量。样品用硝酸-高氯酸(4+1)混合酸消解后加入过氧化氢,并蒸发至近干,残渣溶于硝酸(1+99)溶液中后用于火焰原子吸收光谱法分析,标准曲线分别用上述4种元素的标准溶液制作。按此方法分析了上述6种中草药中铜、铁、锌及锰4种痕量元素,并在此基础上用标准加入法作了回收试验,测得4种痕量元素的回收率在93.5%~109.0%之间。     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

Use of NAA in marine environment and in archaeology in Greece

Neutron activation analysis (NAA) is a very sensitive and accurate multielement analytical method that is widely applied to the investigation of environmental and archaeological problems. The first part of this paper is a review of pollution studies of toxic trace elements in sediments, seawater and marine organisms of Saronikos Gulf, Greece by NAA. The second part of this paper is a review of provenance studies based on minor and trace element research in ancient ceramics, obsidian, flint, limestone, marble and lead by Instrumental NAA, performed at the NCSR Demokritos.     

Electrolysis in nanochannels for in situ reagent generation in confined geometries

In situ generation of reactive species within confined geometries, such as nanopores or nanochannels is of significant interest in overcoming mass transport limitations in chemical reactivity. Solvent electrolysis is a simple process that can readily be coupled to nanochannels for the electrochemical generation of reactive species, such as H(2). Here the production of hydrogen-rich liquid volumes within nanofluidic structures, without bubble nucleation or nanochannel occlusion, is explored both experimentally and by modeling. Devices comprised of multiple horizontal nanochannels intersecting planar working and quasi-reference electrodes were constructed and used to study the effects of confinement and reduced working volume on the electrochemical reduction of H(2)O to H(2) and OH(-). H(2) production in the nanochannel-embedded electrode reactor output was monitored by fluorescence emission of fluorescein, which exhibits a pH-dependent emission intensity. Initially, the fluorescein solution was buffered to pH 6.0 prior to stepping the potential cathodic of E(0)' for the generation of OH(-) and H(2). Because the electrochemical products are obtained in a 2:1 stoichiometry, local measurements of pH during and after the cathodic potential steps can be converted into H(2) production rates. Independent experimental estimates of the local H(2) concentration were then obtained from the spatiotemporal fluorescence behavior and current measurements, and these were compared with finite element simulations accounting for electrolysis and subsequent convection and diffusion within the confined geometry. Local dissolved H(2) concentrations were correlated to partial pressures through Henry's Law and values as large as 8.3 atm were obtained at the most negative potential steps. The downstream availability of electrolytically produced H(2) in nanochannels is evaluated in terms of its possible use as a downstream reducing reagent. The results obtained here indicate that H(2) can easily reach saturation concentrations at modest overpotentials.     

乙基香兰素研究前景

报导了近几十年来国内外关于乙基香兰素的研究进展与动态,并简单介绍了本文作者在该方面所取得的研究成果,参考文献33篇。     

Reactions in droplets in microfluidic channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.     

Conferences in Chemistry Held in 2022

Russian Chemical Bulletin -