离子色谱法同时测定大气可吸入颗粒物PM10中14种水溶性离子

采用离子色谱法同时测定了大气可吸入颗粒物PM10中的多种水溶性阴阳离子。样品采用超纯水超声萃取各种水溶性离子,优化的萃取溶液体积为40mL,萃取时间为15 min,萃取液用0.45μm纤维滤膜过滤,阴、阳离子分别采用响应的离子色谱柱分离,流动相分别采用3.6 mmol/L Na2CO3溶液+0.6 mmol/L NaHCO3溶液,2 mmol/L HNO3溶液,其中阳离子检测未使用抑制器,电导检测器检测。14种离子在一定浓度范围内线性关系良好,相关系数r都>0.999,F-,BrO3-,Cl-,NO2-,Br-,NO3-,PO42-,SO42-等8种阴离子的检出限分别为1.5,7.5,1.6,4.2,6.5,12.5,10.4,3.3μg/L,Li+,NH4+,Na+,K+,Mg2+,Ca2+等6种阳离子的检出限分别为4.6,12.3,8.5,19.8,12.4,17.9μg/L,平均回收率为92.3%~99.7%,标准偏差小于5%。方法适用于同时测定PM10中的多种水溶性离子。     

北京大气颗粒物PM10和PM2.5中水溶性阴离子的组成及特征

利用离子色谱技术对北京PM10和PM2.5中的水溶性阴离子（F^-,Cl^-,NO3^-和SO4^2-）进行了分析测定,并讨论了它们的分布、浓度变化和来源.F^-,Cl^-,NO3^-和SO4^2-离子的总质量分别占PM10和PM2.5总量的18.2%和24.2%,是大气颗粒物的重要组分.其中F^-主要存在于PM10的粗颗粒中,而Cl^-,NO3^-和SO4^2-则主要在细颗粒中富集.PM10和PM2.5中Cl^-在总氯中所占的比例分别达到了49.5%和40.3%,并与总氯具有非常好的相关性.氯在大气中明显富集,其主要的人为来源为煤的燃烧.SO4^2-和NO3^-具有比较好的相关性,其浓度在7月份最高,9、10月较低,进入冬季采暖期之后浓度升高.在PM10和PM2.5中NO3^-与SO4^2-的质量之比分别在0.1～0.6和0.1～0.5之间,说明燃煤对它们的贡献要大于汽车尾气.     

探究黑枸杞中花青素稳定性的生活化实验设计

以黑枸杞为研究对象,从溶液酸碱性、温度、离子种类等方面探究影响黑枸杞中花青素稳定性的因素。结果表明,花青素在弱酸弱碱、低温,含Na+,K+,Mg2+,Ba2+,Cl-,SO42-等离子的溶液中较稳定;在强酸强碱、高温,含Ca2+,NO3-,CO32-等离子的溶液中稳定性较差。Ca2+是造成蒸馏水和自来水提取液颜色差异的主要因素。基于此设计的生活化实验简单、安全、有趣味,易于操作。     

PM_(2.5)中水溶性离子采样及前处理注意事项的探讨

本文采用四通道采样器,使用Teflon和石英膜对环境空气中的PM2.5样品进行采样,并使用超声振荡-离子色谱法对其中的水溶性离子进行分析。分析结果表明,石英膜和Teflon膜本底结果差异性不大,但石英膜本底离子浓度范围相对较宽。Teflon膜适合于PM2.5质量浓度的测量,石英滤膜更适合于冬季PM2.5水溶性离子的检测分析。     

微晶酚酞分离富集分光光度法测定铊(Ⅲ)

建立了利用无毒的微晶酚酞作为固相萃取剂分离富集溶液中痕量Tl(Ⅲ)的方法。在H3PO4介质中,Tl(Ⅲ)在水相中与I-和结晶紫(CV+)形成离子缔合物而被微晶酚酞定量吸附,富集后的Tl(Ⅲ)可直接用光度法测定。控制一定的条件,Tl(Ⅲ)能与常见离子Na+,K+,Al3+,Cu2+,Pb2+,Zn2+,Ba2+,Mn2+,Ca2+,Cd2+,Fe2+等完全分离,且基本不受Cl-,Br-,SO42-,NO3-等阴离子的影响。方法可直接应用于环境水样中痕量Tl3+的测定,富集倍数可达100倍,回收率95.6%~101.8%,检出限为13 ng/L。     

金属离子Na+,Li+及Mg2+与C1O4-和NO3-形成的无水离子缔合物种的从头算量子化学研究

采用量子化学计算方法在B3 LYP/6-311++G**水平下对Na+,Li+和Mg2+与ClO4-和NO3-形成的离子缔合物种的结构以及v1-频率进行了研究,并将结果与SO42-和上述3种阳离子形成的物种进行了对比.在缔合物种结构方面,当阳离子数目≤2时,与SO42-体系相似,ClO4-和NO3-主要与阳离子形成双齿缔合结构,而当阳离子数目＞2时,特别是具有2个正电荷的Mg2+离子数目较多时,由于阳离子间的斥力更大,与阳离 子结合能力较弱的ClO4-和NO3-较难与其形成稳定的离子团簇,而在SO42-体系中,则易形成单齿缔合结构.在v1-频率的变化趋势方面,3种阴离子形成的缔合物种大体相同,说明无水离子团簇的频率变化主要受阳离子性质和缔合结构影响.虽然阴离子性质也有部分影响,但不占主要地位.     

新型水溶性中氮茚衍生物的合成及铜离子荧光探针行为

设计合成了2个新型水溶性中氮茚季铵盐化合物4a{氯化2-[N'-(3-氰基-中氮茚-1-甲酰基)肼基]酰乙基-1-吡啶鎓盐}和4b{氯化2-[N'-(3-氰基-中氮茚-1-甲酰基)肼基]酰乙基-1-(2-甲基吡啶)鎓盐},采用红外光谱、核磁共振、质谱和元素分析对其进行了结构表征,并研究了它们的光谱性质.选取Cu2+,Zn2+,Ca2+,Cr3+,Co2+,Al3+,Mn2+,Ni2+,Ba2+,Hg2+,Fe3+,Cd2+,Mg2+,Pb2+,Li+和Ag+等16种常见金属离子,对2个化合物进行了离子识别实验.结果表明,化合物4a和4b在一定浓度范围内对铜离子均具有良好的选择性识别能力,受常见离子干扰小.由于空间位阻的影响,化合物4a具有比4b更高的灵敏性.     

双通道毛细管离子色谱法同时测定降水中阴、阳离子

采用离子色谱法测定降水中的阴阳离子。F–,Cl–,NO2–,NO3–,SO42–,PO43–6种阴离子的检出限在0.002~0.015 mg/L之间,Na+,NH4+,K+,Mg2+,Ca2+5种阳离子的检出限在0.010~0.025 mg/L之间。阴离子加标回收率在88.4%~109%之间,相对标准偏差小于5%;阳离子加标回收率在85.0%~112%之间,相对标准偏差小于7%。用离子色谱法测定降水中的阴阳离子,操作简单、快捷,灵敏度高。     

替代模板印迹-高效液相色谱测定空气PM2.5中的羰基化合物

以替代模板法制备了分子印迹固相萃取柱（MISPE），该柱能够有效去除空气PM2.5样品分析过程中过量的衍生剂2，4-二硝基苯肼（2，4-DNPH），并能够大幅度浓缩样品溶液，提高羰基化合物的富集效率和监测灵敏度，缩短采样时间。与高效液相色谱联用，实现了对空气PM2.5中的羰基化合物的快速检测。本研究解决了传统固相萃取材料选择性低，不能去除2，4-DNPH干扰的瓶颈问题。本方法用于研究广州市大学城早春季节雾霾天和非霾天羰基化合物水平及其来源，结果发现无论是灰霾天气还是正常天气，14种目标羰基化合物均被检出。研究发现，在污染物排放和天气因素的影响下，灰霾天气羰基化合物总量增高，尤其是异戊醛增长迅速，并且与丙醛浓度变化呈现高度正相关。通过相关性分析，证明除了光化学反应等自然因素，人类活动对广州羰基化合物水平的干扰严重，应引起重视。     

多分离模式液相色谱法同时分析阴、阳离子的研究

采用基于纳米聚合物-硅胶混合技术,同时具有反相、阴、阳离子交换的多分离模式色谱分离功能的Acclaim Trinity P1色谱柱,直接电导检测,建立了同时分析Li+,NH+4,K+,HCOO!,NO!2,Cl!,NO!3和Br!8种离子的分析方法。通过探讨淋洗液对离子保留的影响,优化得到实验条件如下:淋洗液:25 mmol/L乙酸钠+50%(V/V)乙腈,用冰醋酸调至pH 5.0;柱温:30℃;流速:0.50 mL/min;直接电导检测。8种阴阳离子(Li+,NH+4,K+,HCOO!,NO!2,Cl!,NO!3和Br!)能够同时被分离和检测。化肥样品经稀释溶解过滤后直接进样,结果表明,8种离子的线性范围为0.5~200 mg/L,线性相关系数均大于0.9997,相对标准偏差RSD(n=9)为1.3%~2.5%,检出限(S/N=3)在0.16~1.70 mg/L之间。将本方法用于化肥中阴阳离子的测定,加标回收率为95.8%~103.8%。     

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.     

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。     

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。     

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).