悬浮液进样-火焰原子吸收光谱法测定地黄中锌和锰

怀地黄、怀山药、怀牛膝、怀菊花合称"四大怀药",是享誉海内外的名贵中药材,其中,怀地黄有"以邑供天下"的威名,素有"怀参"之美称[1].中药材的性味功能与微量元素具有一定相关性,特别是微量元素锌和锰与人体多种酶有关,对于调节人体的生理机能有独特的作用.对锌、锰元素含量的测定为此药材的品质、疗效提供科学依据.在样品分析中,前处理是一个重要步骤,怀地黄(包括生地黄、干地黄、熟地黄)的预处理方法通常有干法(灰化)、湿法(加酸消化)及微波消化法,前两种方法消化时间长、操作环节多,被测元素丢失或被污染的机会多;后种方法溶样不完全,重现性易受影响.悬浮液进样一原子吸收光谱法测定粮食、茶叶、中草药中微量元素已有报道[2-5].本法采用悬浮液进样处理怀地黄样品,并用火焰原子吸收光谱法测定地黄中锌和锰.     

火焰原子吸收光谱法测定四大怀药中10种元素

对四大怀药(即怀山药、怀地黄、怀菊花及怀牛膝)中的8项微量元素(铜、铁、锌、锰、镍、钴、铬和铅)、2种常量元素钾及钙,用火焰原子吸收光谱法做了测定。比较了水煎酸化和硝酸-高氯酸(4+1)混合酸直接消解两种溶样方法,结果表明:用后一种溶样方法可使上述10种元素从药材中更完全地提取。在所述的最优分析条件下,上述10种元素的质量浓度与其相应吸光度在一定范围内呈线性关系。对方法的回收率和精密度做了试验,测得回收率在97.0%～105.0%之间,相对标准偏差(n=5)均小于5%。     

中草药样品不同预处理方法对微量元素测定结果的影响

探讨了采用不同的预处理方法对中草药中微量元素含量测定结果的影响。结果表明，湿式消化法优于干式灰化法，所测中草药中锌、铜、锰、铁、铅和镉的数值较高，这可能与湿式消化法处理样品时，元素被挥发、损耗和吸附较少有关。     

火焰原子吸收光谱法测定猪肝中铜铁锌

用悬浮液技术及非完全消化法分别处理猪肝样品,建立了悬浮液技术和非完全消化-火焰原子吸收光谱法快速测定猪肝中铜、铁、锌的分析方法。试验表明,在悬浮液中加入适量盐酸可显著提高被测元素的吸光度,试液的粘度与空白溶液的一致,无背景吸收干扰。对非完全消化法样品处理条件、悬浮液的稳定时间及酸的影响进行了考察。相对标准偏差小于4.0%,测定结果与灰化法一致,相对误差小于±1.8%(悬浮液法),±2.7%(非完全消化法)。     

非完全消化-火焰原子吸收光谱法测定水果中铜铁锌

用非完全消化法处理杏、油桃和草莓样品,即在低温下用浓硝酸-高氯酸(3+1)混合酸消解样品,再加入乳化剂TX-10溶解消化过程中所产生的油脂,将所得橙红色的均匀透明溶液用火焰原子吸收光谱法测定其中铜、铁和锌元素的含量.对样品处理条件、混合酸中杂质及共存TX-10的干扰进行了试验.铜、铁和锌的检出限(3s/k)分别为0.019,0.145,0.009 mg·L-1.用此法测定水果实样中铜、铁和锌的含量,所得结果与灰化法测定结果相一致.     

电感耦合等离子体原子发射光谱法测定枸杞中11种元素含量

采用电感耦合等离子体原子发射光谱法测定了枸杞中锌、铅、锰、铁、铬、镁、钙、铜、钠、钾和镉11种元素含量。选择硝酸(2+98)溶液作为介质,选择波长为213.86,220.35,257.61,259.94,267.72,279.08,324.75,317.93,589.59,766.49,226.50 nm 11条谱线依次作为测定锌、铅、锰、铁、铬、镁、钙、铜、钠、钾和镉的分析线,测得11种元素的检出限(3δ)均低于0.07 mg·L~(-1),相对标准偏差(n=11)在0.72%～2.40%之间。比较了常规湿法消化法、高压消化罐法和微波消解法处理样品对测定结果的影响。研究表明,高压消化罐法和微波消解处理样品精密度好。     

ICP-AES法同时测定电铜中九种杂质元素

电铜中微量杂质元素的测定对电铜质量控制十分必要。以往测电铜中微量元素的方法有石墨炉原子吸收光谱法、吸光光度法、电弧粉末发射光谱法等 ,这些方法不同程度地存在缺陷 [1,2 ] 。鉴于 ICP-AES法技术上的逐步成熟 ,本文采用电解法除去主量铜 ,用 BAIRD PS- 6型多道等离子体发射光谱仪测定残液中九种元素 ,方法简便、快速 ,结果准确 ,可用于日常分析。1　试验部分1 .1　仪器与试剂BAIRD ICP2 0 0 0 /PS- 6多道等离子体发射光谱仪单元素标准储备溶液 :分别用光谱纯金属配成1 mg· ml-1溶液 [硝酸 (5 95)介质 ]九种元素混合标准溶…     

微波消解-原子吸收光谱法测定粮谷中铅、铜、镉、镁、锰、铁

用微波消解法进行样品消解,原子吸收光谱法测定了小麦粉国家标准物质中铅、铜、镉、镁、锰、铁6种元素的含量.其中镁、锰、铁用火焰原子化法,铅、铜、镉用石墨炉原子化法,方法的相对标准偏差分别为1.43%(镁),4.72%(镉),5.20%(锰),6.04%(铜),13.8%(铁)及18.7%(铅),检出限分别为0.001(铅及铜),0.000 1(镉),0.01(锰)及O.02(镁和CA)mg·kg-1.     

杏鲍菇多糖和微量元素的含量测定

采用苯酚-硫酸法测定了景宁产杏鲍菇中多糖的含量,并采用等离子体发射光谱法(ICP-AES法)测定了其微量元素的含量.结果表明,多糖测定波长为490nm,在2.04～10.20μg/mL范围内吸光度与被测物含量呈良好的线性关系,r=O.9992,方法的平均回收率为100.8%,RSD=1.3%.杏鲍菇含有丰富的多糖及铜、铁、锰、锌、硒等微量元素,药食两用,具有很高的经济价值和药用价值.多糖测定方法简便、准确、重现性好,可作为杏鲍菇多糖含量的测定方法.     

电感耦合等离子体发射光谱法测定植物油中的磷

用电感耦合等离子体发射光谱法(ICP-AES)测定了植物油中的磷.采用多谱线拟合技术(MSF)校正了铜对P213.617 nm和P214.914 nm光谱干扰.比较了活性炭炭化灰化法和微波消解法两种样品前处理方法对分析结果的影响.结果表明这两种前处理方法所得结果都能与国标磷钼蓝分光光度法的分析结果吻合,其中活性炭炭化灰化法的方法检出限(0.053 mg/kg)较微波消解法的方法检出限(0.42 mg/kg)更低,所以对低含量的磷的检测结果其相对误差及精密度更好.该法应用于植物油中磷的测定.     

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.