Comparison of ion chromatography and capillary electrophoresis for the determination of inorganic ions

The techniques of ion chromatography and capillary electrophoresis are compared as analytical methods for the determination of inorganic anions and cations. Comparison is made in the areas of stage of development, separation efficiency, separation selectivity, analytical performance parameters, method development procedures, applications, strenghts and weaknesses, and future directions. It is shown that the two techniques are complementary rather than competitive, especially with regard to their separation selectivities and the type of applications to which they are most suited.     

The importance of capillary electrophoresis,capillary electrochromatography,and ion chromatography in separations of inorganic ions

The importance of capillary electrophoresis (CE), capillary electrochromatography (CEC), and ion chromatography (IC) in inorganic ion analyses is outlined. Methods for improving the reliability of the CE measurements are briefly described. Selectivity optimization in CE analyses of inorganic cations and anions is discussed. Using the Peakmaster program, CE system peaks (system zones, eigenmobilites) and some important CE parameters, such as effective mobilities, electromigration dispersion, indirect UV, and direct conductivity signals, are predicted and compared with experimental analyses.     

Rapid inorganic ion analysis using quantitative microchip capillary electrophoresis

Rapid quantitative microchip capillary electrophoresis (CE) for online monitoring of drinking water enabling inorganic ion separation in less than 15 s is presented. Comparing cationic and anionic standards at different concentrations the analysis of cationic species resulted in non-linear calibration curves. We interpret this effect as a variation in the volume of the injected sample plug caused by changes of the electroosmotic flow (EOF) due to the strong interaction of bivalent cations with the glass surface. This explanation is supported by the observation of severe peak tailing. Conducting microchip CE analysis in a glass microchannel, optimized conditions are received for the cationic species K+, Na+, Ca2+, Mg2+ using a background electrolyte consisting of 30 mmol/L histidine and 2-(N-morpholino)ethanesulfonic acid, containing 0.5 mmol/L potassium chloride to reduce surface interaction and 4 mmol/L tartaric acid as a complexing agent resulting in a pH-value of 5.8. Applying reversed EOF co-migration for the anionic species Cl-, SO42- and HCO3- optimized separation occurs in a background electrolyte consisting of 10 mmol/L 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 10 mmol/L HEPES sodium salt, containing 0.05 mmol/L CTAB (cetyltrimethylammonium bromide) resulting in a pH-value of 7.5. The detection limits are 20 micromol/L for the monovalent cationic and anionic species and 10 micromol/L for the divalent species. These values make the method very suitable for many applications including the analysis of abundant ions in tap water as demonstrated in this paper.     

Derivatization of inorganic ions in capillary electrophoresis

This review gives a short overview of the main approaches to the derivatization of inorganic ions in capillary electrophoresis (CE) with emphasis on the most recent works. Various derivatization procedures and detection methods are discussed. A brief account of their advantages and limitations is given. More specific areas such as microchip CE, simultaneous separation of anions and cations, and speciation analysis are also briefly discussed.     

毛细管区带电泳技术快速分离检测爆炸残留物中的无机离子

利用间接紫外毛细管区带电泳方法完成了对爆炸残留物中7种无机离子(K+,NH+4,NO-2,NO-3,SO2-4,ClO-3,ClO-4)的分离检测。阳离子测定采用的缓冲体系为10 mmol/L吡啶（pH 4.5）-3 mmol/L冠醚,K+和NH+4在2.6 min内达到基线分离,检出限分别为0.25 mg/L和0.10 mg/L(S/N=3)。阴离子测定采用的缓冲体系为40 mmol/L硼酸-1.8 mmol/L重铬酸钾-2 mmol/L硼酸钠（pH 8.6）,氢氧化四甲铵为电渗流改性剂,5种阴离子在4.6 min内达到基线分离,检出限为0.10～1.85 mg/L。该方法已成功地应用于实际爆炸物样品种类的判定分析,取得了很好的结果。     

Developments in sample preparation and separation techniques for the determination of inorganic ions by ion chromatography and capillary electrophoresis.

A review is presented of sample preparation and separation techniques for the determination of inorganic ions by ion chromatography (IC) and capillary electrophoresis (CE). Emphasis has been placed on those sample treatment methods which are specific to inorganic analysis, and the developments in separation methods which are discussed are those which enhance the capabilities of IC and CE to handle complex sample matrices. Topics discussed include solid-phase extraction for sample clean-up and preconcentration, dialytic methods, combustion methods, matrix-elimination IC, electrostatic IC, electrically polarised ion-exchange resins, electromigration sample preparation in CE, chromatographic sample preparation for CE, use of high-ionic strength background electrolytes, buffering of background electrolytes in CE, use of capillary electrochromatography for inorganic determinations, and methods for the manipulation of separation selectivity in both IC and CE. Finally, some possible future trends are discussed.     

Advances in detection of inorganic ions in capillary electrophoresis

Recent advances in capillary electrophoresis methodology to improve the detection sensitivity for inorganic ions are briefly reviewed. Specifically discussed are current developments of nonabsorbance-based CE detectors and on-capillary enrichment techniques as well as some possible future perspectives.     

Recent advances and trends in capillary electrophoresis of inorganic ions

Capillary electrophoresis (CE) continues its invasion into the domain of inorganic analysis. This review summarizes the progress and significant developments of CE of inorganic ions over the first two years of the new century. As manifested by the substantial number of published articles, this field is still witnessing a growing activity of many separation scientists. To provide an in-depth treatment of fundamental and methodological aspects of inorganic ion analysis by CE, an extensive fraction of the relevant literature is covered whereas only most innovative application reports are briefly considered. Most of the recent advancements have focused on CE system modernization designed to improve a limited detection sensitivity, which still remains a major obstacle to overcome in order to ensure the method's wider practical acceptance. Attention is also given to how and in which directions the future research could be performed to implement CE in routine inorganic analysis.     

Application of capillary isotachophoresis and capillary zone electrophoresis to the determination of inorganic ions in food and feed samples

The purpose of this review is to summarise critically the possibilities of capillary isotachophoresis and capillary zone electrophoresis for the determination of inorganic ions in food and feed samples. This article covers papers published since 1977.     

Determination of inorganic ions in food and beverages by capillary electrophoresis

A review of the applications of electrophoresis to the determination of inorganic anions (sulphate, sulphite, phosphate, nitrate, nitrite and halides) and inorganic cations (ammonium, alkali and alkaline metals and trace elements) in food and beverages is presented.     

Evaluation of weak ion association between tetraalkylammonium ions and inorganic anions in aqueous solutions by capillary zone electrophoresis

The evaluation of weak ion association between eleven (11) inorganic anions (charge -1 to -3) and five n-tetraalkylammonium ions, R4N+ (R: methyl, Me; ethyl, Et; propyl, Pr; butyl, Bu; pentyl, Am) in aqueous media at 25 degrees C was studied. The analysis of ion association equilibria was carried out under acidic condition (formate buffer, pH 3.5) at low separating potential (-10 kV) using a coated capillary with suppressed electroosmotic flow (micro = 4 x 10(-5) cm2 V(-1) s(-1)). Direct UV detection was done at anode (lambda = 220 nm). The combination of the aforementioned conditions ensured that ion association constants, Kass, between n-tetraalkylammonium ion and the small inorganic anions were reliably determined after a non-linear least squares (NLLS) treatment of the measured anion's mobility. Like their larger counterparts, small anions showed increased interaction with an increase in size of pairing ions. Moreover, for a specific cation, the interaction of small anions increased with an increase in size of the hydrated anions as reflected by the relationship between the Kass and the Stokes' radius. A favourable comparison exists between the results presented in this work and those previously documented from other analytical techniques like conductometry. Qualitatively, the mobility of the anions appeared to obey the Hückel's model more closely than the more elaborate Zwanzig and Hubbard-Onsager models.     

Analysis of inorganic and small organic ions with the capillary electrophoresis microchip

Capillary electrophoresis microchip devices are receiving considerable attention due to their versatility, portability, and sample handling capabilities. This article is a comprehensive review of the analysis of inorganic and small, charged organic species on microchip platforms. The application of conductivity, amperometry, laser-induced fluorescence, absorbance, and chemiluminescence detection methods are discussed. The potential utilization of these devices for miniaturized analytical systems is described.     

毛细管区带电泳技术快速分离检测爆炸残留物中的无机离子

利用间接紫外毛细管区带电泳方法完成了对爆炸残留物中7种无机离子(K+,NH+4,NO-2,NO-3,SO2-4,ClO-3,ClO-4)的分离检测。阳离子测定采用的缓冲体系为10 mmol/L吡啶（pH 4.5）-3 mmol/L冠醚,K+和NH+4在2.6 min内达到基线分离,检出限分别为0.25 mg/L和0.10 mg/L(S/N=3)。阴离子测定采用的缓冲体系为40 mmol/L硼酸-1.8 mmol/L重铬酸钾-2 mmol/L硼酸钠（pH 8.6）,氢氧化四甲铵为电渗流改性剂,5种阴离子在4.6 min内达到基线分离,检出限为0.10～1.85 mg/L。该方法已成功地应用于实际爆炸物样品种类的判定分析,取得了很好的结果。     

Simultaneous determination of inorganic and organic gunshot residues by capillary electrophoresis

A capillary electrophoresis method was developed to analyze simultaneously 11 organic and 10 inorganic components of gunshot residues as a cheaper and possibly more specific method comparing to traditional techniques. Pre-capillary complexation and simultaneously a micellar phase were combined to determine not only the metal but also the organic residues from a firearm. In order to test the possibility to apply the developed method to real cases, residues from shot samples from different firearms were analyzed and their results were compared with those obtained with electrothermal atomic absorption spectroscopy, an established technique for gunshot residue analysis. Good agreement between both techniques for lead was found.     

Direct determination of bromide ions in seawater by capillary zone electrophoresis using polyethyleneimine-coated capillaries

A rapid and simple capillary electrophoretic method was developed for the direct determination of bromide ion in seawater. We have found an effective method, based on the use of polyethyleneimine-coated capillaries and the addition of sodium chloride to the background electrolyte. The use of coated capillaries with a cationic polymer changes the direction of the electroosmotic flow in the capillary, which favors the migration speed of the bromide ion and enables the use of low salt concentrations in the separation electrolyte. Bromide ion in seawater can be determined within 2 min using this system and 20 mmol L^-1 NaCl-containing separation electrolyte. The detection limit for the bromide ion was 0.45 g ml^-1. The method was applied to the determination of bromide ion in seawater samples collected from the Bosphorus and the Black Sea. Bromide contents in samples from 0 to 72 m depths varied between 33.2 and 72.8 mg L^-1 with a mean 3.0% RSD.     

Environmental monitoring of wastewater using capillary ion electrophoresis

Capillary ion electrophoresis (CIE) is a capillary electrophoretic technique which has been developed for the rapid analysis of low-molecular-mass inorganic and organic ions. Anion and cation analysis of wastewater samples from a meat processing plant will be discussed. The wastewater samples were collected above, at point of discharge, and at various points downstream from the plant. The purpose of the analysis was to investigate dilution effects of the wastewater as it mixes with the stream water. CIE allows for rapid analysis times (typically less than 5 min) with little sample preparation required.     

毛细管区带电泳法间接测定红细胞中的主要无机阳离子

建立了间接测定红细胞中主要无机阳离子的毛细管区带电泳方法, 考察了背景溶液pH、咪唑和酒石酸浓度等对无机离子分离效果及峰面积的影响. 以10 mmol/L咪唑-4 mmol/L酒石酸(pH 5.5)为背景, 在15 kV、214 nm的条件下, 对红细胞中K 、Mg2 、Ca2 和Zn2 进行了定性、定量分析, 回收率在96%～104%之间, 迁移时间和峰面积的相对标准偏差分别低于0.76%和2.8%(日内), 0.85%和3.7%(日间). 所建方法有望成为一种测定细胞内离子含量的辅助方法.     

毛细管电泳分析中手性化合物的定性检测

毛细管电泳(CE)作为一种新型分离分析技术,具有分离效率高、分析速度快、样品用量少、分离模式灵活多样等众多优势,在手性物质分离等领域应用广泛。在以往的工作中,手性化合物的CE分离模式、手性拆分剂选择及提高分离度等研究已作了详尽报道,而成功分离后的手性物质定性、对映体出峰顺序确认等问题也至关重要。该文以CE手性化合物分离分析中是否依赖标准品分类,及其定性检测方法进行了总结。利用CE分离分析手性样品,若待测物有手性对映体标准品时,其定性通常通过比较标准品迁移时间或标准加入法完成。基于检测器的不同,依赖标准品的CE分析主要分为光学、质谱和电化学3类检测模式。其中光学检测又包含紫外-可见(UV)、激光诱导荧光(LIF)、化学发光(CL)等多种检测方式。不同的检测方式决定了样品前处理方式的差异,随之形成的谱图及手性化合物定性方式也大相径庭。当缺少手性对映体标准品时,可用的CE手性分离分析方法主要有酶消解和抗体添加法、计算法等。前两种方法主要依据对映体与特定消解酶或抗体间的相互作用,完成手性物质的选择定性,适用范围均较局限。相比较,借助理论计算,使CE结合圆二色光谱(CD)的计算法操作简单,定性准...     

Monolithic stationary phases for fast ion chromatography and capillary electrochromatography of inorganic ions

The focus of this review is on current developments in monolithic stationary phases for the fast analysis of inorganic ions and other small molecules in ion chromatography (IC) and capillary electrochromatography (CEC), concentrating in particular on the properties of organic (polymer) monolithic materials in comparison to inorganic (silica-based) monoliths. The applicability of these materials for fast IC is discussed in the context of recent publications, including the range of synthesis and modification procedures described. While commercial monolithic silica columns already show promising results on current IC instrumentation, polymer-based monolithic stationary phases are currently predominantly used in the capillary format on modified micro-IC systems. However, they are beginning to find application in IC particularly under high pH conditions, with the potential to replace their particle-packed counterparts.     

Application of capillary electrophoresis to the analysis of inorganic ions in environmental samples

A comprehensive review is presented of the state-of-the-art of capillary electrophoresis for application to the analysis of inorganic species, mainly ions, in environmental samples. This brief review covers the developments principally in sensitivity and matrix interference for the determination of inorganic ions in the following samples: drinking, mineral, surface, and ground waters, rainwater, snow, seawater, brine and waste waters, aerosol, and others. References published mainly from 1995 to 1997 were summarized in this review.