磁性离子印迹技术用于元素形态分离分析

元素的形态决定了其在环境和生物过程中的不同行为,形态分析正在被分析化学、环境化学、地球化学、生态学、农学和生物医学等众多学科所关注。环境和生物样品基质复杂、化学形态多样、含量低且易转化是元素形态分析面临的挑战,因此对元素形态的甄别、定量、生态毒性评价和生理功能研究需要对原生形态进行高选择性识别和高效率分离。固相萃取是一种有效应对以上难题的方法,但现有材料和方法远不能满足要求。离子印迹聚合物可与印迹金属离子特异性结合,具有准确、灵敏、可靠的特点,近年来在元素形态分离富集和分析检测方面得到了较为广泛的应用。鉴于非磁性吸附剂在固相萃取操作时,需要将分散在样品溶液中的吸附材料经过离心或过滤分离,操作比较繁琐费时,而磁性材料易被外部磁场快速分离,因此操作简便快速的磁固相萃取正成为元素形态分离富集中一种极具潜力的方法。这篇综述系统总结了离子印迹技术的最新进展,包括离子印迹技术的原理、离子印迹聚合物的制备方法,并根据元素形态分析中离子印迹磁固相萃取的发展现状,分析了离子印迹技术所面临的挑战,最后对元素形态分析中离子印迹技术的未来发展方向和策略提出了建议,提出开发基于有机-无机杂化聚合的多功能磁性离子印迹纳米复合物用于样品的前处理是建立识别选择性高、分离能力强、吸附容量大、形态稳定性好的形态分析方法的一种重要举措。     

砷形态分析方法进展

对光变分析法,高效液相色谱法,毛细管电泳法以及气相色谱法在砷形态分析中的应用进行了评述,比较了各种方法的优缺点,引用文献82篇。     

Optimization of capillary zone electrophoresis parameters for selenium speciation

The behaviour of four biologically relevant selenium compounds (Se(VI), Se(IV), selenomethionine and selenocystine) in capillary zone electrophoresis (CZE) was investigated. Parameters which affect the separation, detection and sample introduction were investigated to improve the sensitivity of the analysis. Short-term repeatability was evaluated and detection limits were found to be in the g·l^–1 range.     

离子液体在色谱中的应用

离子液体是当前化学研究领域的一个热点,它在化学的各个领域都有研究和应用。该文就离子液体在毛细管电泳、气相色谱、高效液相色谱中的应用研究进展进行了较为详细的评述,对离子液体的分离检测作了简单的介绍,并对离子液体在色谱研究应用中的发展进行了展望。     

The ICP-MS approach to environmental studies

The certification of marine materials for trace metals is a process which challenges every technique involved, especially if a technique is as recent as inductively coupled plasma mass spectrometry (ICP-MS), Developmental work was required for several materials (natural waters, biological materials, marine sediments). It is reviewed here, in an attempt to show how one can take full advantage of ICP-MS. This includes a review of the digestion procedures developed for the multielement analysis of biological materials and marine sediments in order to minimize spectroscopic interferences. The multielement analysis of natural waters is also reviewed, in particular that of saline waters which requires a separation of the analytes from the alkali and alkaline earths elements and a preconcentration of the analytes on a column of silicaimmobilized 8-hydroxyquinoline. The potential of performing this separation/preconcentration procedure on-line is showed using both published and original results. Finally, the application of ICP-MS to speciation is illustrated by the determination of methylmercury in biological materials after extraction, and by the determination of arsenic species by high performance liquid chromatography coupled to ICP-MS.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, AustriaThe work described was carried out while the author was a Research Associate at the Analytical Chemistry Section, Chemistry Division, National Research Council of Canada, Ottawa, K1A OR9, Canada     

Capillary electrophoresis for the speciation of arsenic

Capillary zone electrophoresis (CZE) with on-line UV-detection was used for the determination of arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine. The method is simple and rapid (<10 min) and allows the determination of six different arsenic species without sample pretreatment. Several instrumental parameters were studied to obtain the best performance (pH of buffer, injection mode, injection time, applied voltage). To determine the arsenic compounds, the instrument was used with a negative potential applied to the injection side of the capillary so that the anions can migrate towards the anode because of their own mobility and charge. The capillary wall was coated with an electro-osmotic flow modifier which reversed the electro-osmotic flow and thus increased also the overall migration of the anions towards the anode. The influence of high concentrations of matrix components such as NaCl, KNO₃ and NaNO₃, as well as the presence of acids such as HNO₃ and HCl was studied. CZE was used for the determination of the oxidation state of arsenic in percolate waters and in the leachate of solidified arsenic containing waste. The lowest detectable concentration was about 100 g/l. A comparison with the results obtained with hydride generation coupled to ICP-MS was made.     

A multinjection strategy for mercury speciation

A multiinjection strategy has been developed to increase the sampling throughput of the high-performance liquid chromatography determination of inorganic-mercury, methylmercury, ethylmercury and phenylmercury. The method involves the injection of samples each 3.5 min, in spite of the fact that phenylmercury retention time corresponds to 9.04 min. In the selected conditions, the sampling frequency was 11 h⁻¹ in front of that of 6 h⁻¹, obtained by conventional injection of each sample after the complete elution of Hg species. Additionally, the analytical reagents consumption was reduced drastically in almost 50%. The main characteristics of the chromatographic separation were maintained and only the resolution of phenylmercury was reduced from 10.3 to 1.7 and that of ethylmercury from 4.6 to 3.1.     

Trace element speciation by ICP-MS in large biomolecules and its potential for proteomics

Latest studies on the chemical association of trace elements to large biomolecules and their importance on the bioinorganic and clinical fields are examined. The complexity of the speciation of metal-biomolecules associations in various biological fluids is stressed. Analytical strategies to tackle speciation analysis and the-state-of-the-art of the instrumentation employed for this purpose are critically reviewed. Hyphenated techniques based on coupling chromatographic separation techniques with ICP-MS detection are now established as the most realistic and potent analytical tools available for real-life speciation analysis. Therefore, the status and potential of metal and semimetals elemental speciation in large biocompounds using ICP-MS detection is mainly focused here by reviewing reported metallo-complexes separations using size-exclusion (SEC), ion-exchange (IE), reverse phase chromatography (RP) and capillary electrophoresis (CE). Species of interest include coordination complexes of metals with larger proteins (e.g. in serum, breat milk, etc.) and metallothioneins (e.g. in cytosols from animals and plants) as well as selenoproteins (e.g. in nutritional supplements), DNA-cisplatin adducts and metal/semimetal binding to carbohydrates. An effort is made to assess the potential of present trace elements speciation knowledge and techniques for "heteroatom-tagged" (via ICP-MS) proteomics.     

Monolithic chromatography for elemental and speciation analysis

Monolithic supports are increasingly used in the field of chromatography. They are appropriate for different applications (e.g., separation of biomolecules, organic acids and inorganic anions). However, only a few research groups are investigating the potential of using monolithic phases for rapid separation of metal cations and elemental speciation analysis.Monolithic supports based on porous monolithic silica have been successfully applied in separation of alkaline-earth and transition-metal cations in environmental waters and high ionic-strength samples.The present review covers applications of monolithic supports for chromatographic separation of metal cations and the potential for using monolithic chromatography in elemental speciation analysis. We critically evaluate the performances and the advantages of monolithic supports and compare them to conventional particle-packed chromatographic supports.     

Studies on organo-mercury compounds speciation

Four studies on organo-mercury compounds speciation carried out in the analytical chemistry laboratory of the University of Santiago are briefly described and discussed. Search for new methods of separation based on liquid chromatography as well as quality control and application studies have been started and the results obtained up to the end of 1990 are presented.     

g-C3 N4 富集结合毛细管电泳与电感耦合等离子体质谱联用分析西瓜中硒形态

硒是人体所必需的微量元素之一,对人身体健康非常重要。该工作称取2.0 g三聚氰胺于反应釜中,在600℃下密闭加热2 h,冷却至室温,取0.5 g上述产物置于烧杯中在室温下超声10 h,静置30 min,取上层乳白色溶液于60℃下烘干,即得类石墨烯氮化碳（g-C₃ N₄ ）。所制备的g-C₃ N₄ 经傅里叶变换红外光谱（FT-IR）、X射线粉末衍射（XRD）、场发射环境扫描电子显微镜（SEM）进行表征,证明g-C₃ N₄ 已经成功合成。建立了毛细管电泳-电感耦合等离子体质谱（CE-ICP-MS）联用技术测定西瓜中硒形态的新方法。用胃蛋白酶作提取剂及超声波辅助提取西瓜中的硒形态,经g-C₃ N₄ 富集、长100 cm内径100 μm毛细管分离,电泳电压为22 kV,缓冲液为8 mmol/L NaH₂ PO₄ -12 mmol/L H₃ BO₃ -0.2 mmol/L十六烷基三甲基溴化铵（CTAB）（pH 9.2）,于11 min内完全分离6种硒形态。所建立的方法检测速度快、灵敏度高,采用CH₄ 作动态反应气消除干扰。硒脲（SeUr）、硒代胱氨酸（SeCys₂ ）、硒代蛋氨酸（SeMet）、亚硒酸钠（Se（Ⅳ））、硒酸钠（Se（Ⅵ））、硒代乙硫氨酸（SeEt）的线性范围（按Se计）分别为0.017~20 μg/L、0.091~50 μg/L、0.032~40 μg/L、0.023~60 μg/L、0.015~75 μg/L、0.015~30 μg/L。各硒形态的线性相关系数均大于0.9995,SeUr、SeCys₂ 、SeMet、Se（Ⅳ）、Se（Ⅵ）、SeEt的检出限分别为6.2、30、11、8.2、48、5.5 ng/L,回收率为96.0%~106%,RSD < 3%。将本方法应用于西瓜中硒形态分析,结果令人满意。     

Organotin speciation in environmental samples by capillary gas chromatography and pulsed flame photometric detection (PFPD)

Pulsed flame photometric detection (PFPD) for gas chromatography was applied to organotin compounds as standards and in environmental samples. Ethylated organotin species (n-propyl-, n-butyl- and phenyl-) were extracted from spiked artificial seawater and from an environmental sample. Selectivity towards tin is shown in the analysis of highly polluted seawater samples from a commercial port where no significant interferences are found. The self-cleaning capability and long-term stability of PFPD is shown in this work during 140 days of continuous operation. The absolute limit of detection for this capillary GC–PFPD technique ranged from 0.2 to 0.4 pg (Sn) for tetraethyl- to tetraphenyl-tin, allowing determination of sub-nanogram/litre concentrations of organotin compounds. © 1997 John Wiley & Sons, Ltd.     

Speciation of arsenic compounds by coupling high-performance liquid chromatography with inductively coupled plasma mass spectrometry

There is considerable evidence that toxicity and physiological behavior of arsenic depends on its chemical forms. Arsenic speciation became therefore the subject of increasing interest in recent years. A sensitive method for the determination of arsenic species has been developed. The proposed procedure involves the use of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Six arsenic compounds were separated by anion-exchange chromatography with isocratic elution using tartaric acid as mobile phase with an elution order: arsenocholine, arsenobetaine, dimethylarsinic acid, methylarsonic acid, arsenous acid and arsenic acid. The chromatographic parameters affecting the separation of the arsenic species were optimized. Analytical characterization of the method has been realized with standard solutions. The detection limits for six arsenic compounds were from 0.04 to 0.6 g/L as As element. The repeatability (expressed by R.S.D) was better than 7% for all investigated compounds. The HPLC-ICP-MS system was successfully applied to the determination of arsenic compounds in environmental and biological samples in g/L level.     

Separation assay of histamine and its metabolites in biological specimens

This review summarizes the determination methods for histamine and the metabolites in biological specimens by separation techniques, such as gas chromatography, liquid chromatography and capillary electrophoresis. The typical applications using these methods are also described in this review together with the characteristics of the methods. Copyright (c) 2008 John Wiley & Sons, Ltd.     

多维高效液相色谱/毛细管电泳模式在蛋白组研究中的应用

对多维高效液相色谱/毛细管电泳模式的发展及其在蛋白质和多肽分析中的应用进行了系统综述。该模式具有快速、重现性好、易于实现自动化的优点,很容易实现和质谱的联用,对于在样品中丰度低和疏水性强的蛋白质的分析也具有明显的优势。引文67篇。     

Evaluation of a purge-and-trap injection system for capillary gas chromatography-microwave induced plasma-atomic emission spectrometry for the determination of volatile selenium compounds in water

A method is presented for the selective determination of the volatile selenium species dimethylselenide and dimethyldiselenide, using a commercially available purge-and-trap injection system coupled to capillary gas chromatography-microwave induced plasma-atomic emission spectrometry. The efficiency of the purging step was evaluated and the parameters affecting the purge and trap processes were optimized. The method was applied to the determination of volatile selenium compounds in lake water. Relative detection limits of 2ng/l for dimethylselenide and dimethyldiselenide, corresponding to an absolute detection limit of 10 pg, were achieved.     

Design of experiment techniques for the optimization of chromatographic analysis conditions: A review

Design of experiment (DoE) techniques have been widely used in the field of chromatographic parameters optimization as a valuable tool. A systematic literature review of the available DoE techniques applied to the development of a chromatographic analysis method is presented in this paper. First, the most common available designs and the implementation steps of DoE are comprehensively introduced. Then the studies in recent 10 years for the application of DoE techniques in various chromatographic techniques are discussed, such as capillary electrophoresis, liquid chromatography, gas chromatography, thin-layer chromatography, and high-speed countercurrent chromatography. Current problems and future outlooks are finally given to provide a certain inspiration of research in the application of DoE techniques to the different chromatographic techniques field. This review contributes to a better understanding of the DoE techniques for the efficient optimization of chromatographic analysis conditions, especially for the analysis of complex systems, such as multicomponent drugs and natural products.     

Front Cover: Method development for the investigation of Mn2+/3+, Cu2+, Co2+, and Ni2+ with capillary electrophoresis hyphenated to inductively coupled plasma–mass spectrometry

The lifetime of lithium ion batteries (LIBs) decreases under continuous cycling due to various degradation processes, such as dissolution of transition metals (TMs) from the electrodes. Therefore, suitable methods to analyze the oxidation states of TMs are mandatory to better understand the dissolution mechanisms of TMs from positive and negative electrodes (LIBs). To investigate the dissolution of Mn²⁺ and Mn³⁺ in electrolytes of LIBs, a previously implemented capillary electrophoresis (CE) method with UV/Vis spectroscopy detection was further developed with the aim of higher sensitivities and additional detection of other dissolved divalent TMs such as Co²⁺, Ni²⁺, and Cu²⁺. Therefore, inductively coupled plasma–mass spectrometry was applied instead of UV/Vis for detection. This also allows the use of Ga³⁺ instead of the previously used Cu²⁺ as an internal standard, which solves the limitation of this method for cycled LIBs due to copper dissolution from the copper-based current collector. The CE buffer based on sodium diphosphate as complexing agent for the stabilization of Mn³⁺ and cetyltrimethylammonium bromide as dynamic capillary wall modifier was optimized in terms of concentrations and pH. Finally, both manganese species and Co²⁺, Ni²⁺, and Cu²⁺ could be analyzed within 15 min. With this improved method, the dissolution of TMs in LIBs for positive electrode materials such as LiNi_0.5Mn_1.5O₄ (LNMO) or LiNi_xCo_yMn_zO₂ (NCM, x + y + z = 1) can be studied in future in more detail.     

Chiral Separations of Pyrethroic Acids Using Cyclodextrin Selectors

Pyrethroid insecticides are broadly used. They have low toxicity for warm-blooded living creatures, but high toxicity for both insects and fish. Therefore, it is important to reduce the environmental impact of pyrethroids. Pyrethroic acids are chiral compounds. An effective way to decrease pollution is to use enantio-pure insecticide products instead of their racemic mixtures. Enantiomer-pure products require enantiomer selective synthesis and analysis. The chiral selective analysis of pyrethroic acids (an intermediate of pyrethroids) is also important in terms of process control and from the point of view of their degradation metabolism in the environment. This study used various enantiomeric selective chromatographic methods for the separation of different pyrethroic acids, including gas chromatography, supercritical fluid chromatography and capillary electrophoresis. Systematic experiments were conducted to find the optimum conditions for their chiral separation. The employed enantio-selective agents were cyclodextrin derivatives with different ring sizes and substitution patterns. The β-cyclodextrin proved to be excellent for the chiral separation of these acids. The different chiral recognition mechanisms were established using different ring-sized cyclodextrins. The results of these systematic studies demonstrated the correlations of the chiral selectivity features of selectors and the structures of analytes.     

Paradigms in isotope dilution mass spectrometry for elemental speciation analysis

Isotope dilution mass spectrometry currently stands out as the method providing results with unchallenged precision and accuracy in elemental speciation. However, recent history of isotope dilution mass spectrometry has shown that the extent to which this primary ratio measurement method can deliver accurate results is still subject of active research. In this review, we will summarize the fundamental prerequisites behind isotope dilution mass spectrometry and discuss their practical limits of validity and effects on the accuracy of the obtained results. This review is not to be viewed as a critique of isotope dilution; rather its purpose is to highlight the lesser studied aspects that will ensure and elevate current supremacy of the results obtained from this method.