石墨炉原子吸收法测定美白化妆品中铅和镉

本文采用石墨炉原子吸收法测定了美白化妆品中铅、镉含量.铅、镉测定的线性范围分别为0～176 ng/mL、0～88 ng/mL,相关系数r均为0.9998,回收率分别为98.2%～101.1%和98.9%～101.8%,相对标准偏差分别为1.73%和1.46%.     

纳米Al2O3微柱分离/富集-石墨炉原子吸收法测定环境试样中的痕量铅和镉

本文将纳米氧化铝微柱分离系统与石墨炉原子吸收光谱法联用,用于测定环境水样中的痕量铅和镉。较系统地考察了纳米Al2O3材料对镉和铅离子的吸附性能及影响因素;在优化的实验条件下本法对Pb和Cd的检出限(3σ)分别为0.189 ng/mL和0.0039 ng/mL;RSD%分别为3.9%和2.9%。     

微波消解-石墨炉原子吸收法测定酵母粉中的微量铅和镉

本文采用微波消解-石墨炉原子吸收法直接测定酵母粉中微量铅和镉的含量。利用硝酸和过氧化氢消解样品,对微波消解的条件,基体改进剂的选择,铅原子化温度的效果以及常见元素对测定的干扰进行了研究。在优化的实验条件下,方法对铅和镉的检出限(3σ)分别为0.062 ng/mL和0.013 ng/mL,相对标准偏差(RSD)分别为0.64%~1.11%、0.75%~4.70%,加标回收率在95.00%~102.0%之间。本法已用于酵母粉中微量铅和镉的测定,分析结果与电感耦合等离子体-质谱(ICP-MS)法具有良好的一致性。     

微波消解石墨炉原子吸收法测定人发中的铅、镉

采用石墨炉原子吸收分光光度法(GFAAS)测定人发中的铅、镉含量.采用微波消解法消解样品,加入(NH4)2SO4+KH2PO4基体改进剂消除干扰,对消化剂种类、消解压力、仪器条件等进行了探索.方法简便、准确度高,Pb和Cd的平均回收率分别为101.8%和107.1%,相对标准偏差(RSD)为5.14%和6.80%,方法检出限Pb为9.53 ng/mL,Cd为0.78 ng/mL.     

微波消解–石墨炉原子吸收光谱法测定露酒中的铅

建立一种微波消解–石墨炉原子吸收光谱法测定露酒中铅的方法。样品蒸干后经微波消解前处理,然后用石墨炉原子吸收光谱法测定露酒中的铅的浓度,铅的浓度在0.0~20.0 ng/mL范围内呈良好的线性关系,线性相关系数为0.9996,取样2.00 mL定容至25.0 mL,得方法的检出限为0.003 mg/L,方法的定量限为0.010 mg/L。测定结果的相对标准偏差为3.4%~5.5%,加标回收率为88%~104%。该法具有灵敏度高,准确度、精密度良好,检测过程快速、省力等优点,适合日常批量检测。     

微波消解–石墨炉原子吸收法测定化妆品中的铅

建立了微波消解–石墨炉原子吸收光谱法测定化妆品中铅的方法。探讨了样品前处理条件、基体改性剂的选择和优化、石墨炉升温条件等对测定结果的影响。在优化的试验条件下,铅的质量浓度在0~100 ng/mL范围内与吸光度具有良好的线性关系,线性相关系数r=0.9991,检出限为0.33 ng/mL。用该法对5种化妆品中的铅进行测定,加标回收率在95.0%~106.1%之间,测定结果的相对标准偏差不大于3.6%。该方法可应用于化妆品中痕量铅的分析。     

石墨炉原子吸收法测定人发中镉和铅

本法用酸消化发样,然后用石墨炉原子吸收法测定其中的镉和铅。该法与萃取火焰原子吸收法比较,其优点是操作简便,灵敏度和准确度较高。测定镉和铅的最低量分别为2×10~(12)克、1.6×10~(11)克;相对标准偏差分别为0.005,0.095;回收率分别为95—108％、96.3—104％。     

石墨炉原子吸收法快速测定血液中铅和镉

建立了快速测定血液中铅和镉的石墨炉原子吸收光谱法。使用5%硝酸溶液对样品进行脱蛋白处理,然后在旋涡混合器上振摇,离心后取上清液上石墨炉原子吸收进行测定。 结果表明,Pb、Cd工作曲线线性关系良好,相关系数均大于0.9994;方法检出限分别为4.32μg/L和0.27μg/L;Pb的回收率为91.60%～97.31%,镉的回收率为97.04%～98.86%;Pb测定的RSD（n=7）为2.35%,Cd测定的RSD（n=7）为1.53%。冻干牛血铅、镉标准物质GBW09139k和GBW09140k的测定值与参考值吻合。该方法快速准确,精密度、准确度、检出限等测定结果令人满意。可以作为日常血铅、血镉的检测的方法。     

双硫腙修饰纳米TiO2分离富集石墨炉原子吸收光谱法测定水样中痕量金属离子

建立了双硫腙修饰纳米TiO2分离富集-石墨炉原子吸收光谱法测定水样中痕量镉、铬和铅的新方法,优化了纳米TiO2-双硫腙对试样中这3种痕量物质的吸附和解吸条件。结果表明,在pH 5.0时,镉、铬和铅可被定量吸附,静态饱和吸附容量分别为13.3、5.5、21.8 mg/g。吸附的各种金属离子可用5 mL 0.1mol/L的硝酸完全洗脱。该方法对Cd2+、Cr3+和Pb2+的检出限(3σ,n=11)分别为0.18、0.51、1.92 ng/L,相对标准偏差分别为2.8%、2.3%和1.0%,加标回收率为96%～101%。该方法已成功应用于环境水样中镉、铬和铅的测定。     

石墨炉原子吸收光谱法快速测定血液中铅和镉

建立了石墨炉原子吸收光谱法快速测定血液中铅和镉的方法。使用5%硝酸溶液对样品进行脱蛋白处理,然后在旋涡混合器上振摇,离心后取上清液在石墨炉原子吸收光谱仪上进行测定。结果表明,Pb、Cd工作曲线线性关系良好,相关系数均大于0.999 4;方法检出限分别为4.32μg/L和0.27μg/L;Pb的加标回收率为91.6%～97.3%,镉的加标回收率为97.0%～98.9%;Pb测定的RSD(n=7)为2.4%,Cd测定的RSD(n=7)为1.5%。冻干牛血铅、镉标准物质GBW09139k和GBW09140k的测定值与参考值吻合。方法快速准确,精密度、准确度、检出限等测定结果令人满意,可以作为日常血铅、血镉的检测的方法。     

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。     

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.     

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.     

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。     

Gemini表面活性剂合成进展*

系统总结了近百种Gemini表面活性剂的合成路线和方法,并且按照其结构特点分门别类地进行比较和归纳,对今后Gemini表面活性剂的合成发展方向提出了一些看法,这对促进此类新颖表面活性剂的工业化进程将具有指导意义。     

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.     

Trends in education in analytical chemistry

Summary At the session of the WPAC of Fechem on education in analytical chemistry it was concluded that it is now essential to include chemometrics and basic knowledge of computers in all courses on analytical chemistry.

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Tendenzen in der analytisch-chemischen Ausbildung

Zusammenfassung Bei einer Tagung der WPAC über die Lehre auf dem Gebiet der analytischen Chemie wurde bei der Betrachtung neuer Aspekte festgestellt, daß vor allem Chemometrie und Grundkenntnisse in Computertechnik in die Ausbildung aufgenommen werden sollten.

     

钙与人体及临床

钙是宏量元素，是人体中含量较高的元素之一，体内99％的钙构成骨骼和牙齿以及维持骨骼结构，1％的钙调节人体重要生理功能。钙的含量过高或过低都与许多疾病有关，只有保持一种平衡状态，才能使机体处于正常环境。     

AGET ATRP in the Presence of Air in Miniemulsion and in Bulk

Summary: The recently developed initiation system, activators generated by electron transfer (AGET), is used in atom transfer radical polymerization (ATRP) in the presence of a limited amount of air. Ascorbic acid and tin(II ) 2‐ethylhexanoate are used as reducing agents in miniemulsion and bulk, respectively. An excess of reducing agent consumes the oxygen present in the system and, therefore, provides a deoxygenated environment for ATRP. ATRP of butyl acrylate is successfully carried out in miniemulsion and in the presence of air. During polymerization the radical concentration remains constant. The polymerization reaches over 60% monomer conversion after 6 h, which results in polymers with a predetermined molecular weight = 14 000 g · mol⁻¹ and a low polydispersity ( = 1.23). AGET ATRP of styrene is also successful in bulk in the presence of air, as evidenced by linear semi‐logarithmic kinetics, which leads to polystyrene with an of 13 400 g · mol⁻¹ and a low polydispersity index ( = 1.14).

Appearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).