Flow-Based Methods with Chemiluminescence Detection for Food and Environmental Analysis: A Review

This paper presents an overview of flow-based methods in food and environmental analysis using chemiluminescence (CL) detection covering the period from 2005 to the present. The review discussses both automated flow methods of analysis [such as flow-injection analysis (FIA), sequential-injection analysis (SIA) and their variants] and separation techniques [liquid chromatography (LC) and capillary electrophoresis (CE) coupled to CL detection]. The most widely used CL reactions are presented together with representative applications in food and environmental analysis (determination of naturally occurring compounds, contaminants, additives as well as determination of inorganic and organic compounds).     

毛细管电泳与化学发光检测联用方法的研究进展

毛细管电泳由于其超高的分离效率广泛应用于生物医药、环境监测、食品科学以及公共安全等领域。然而,由于毛细管电泳具有进样量较少、检测光程较短等缺点,需要与高灵敏度检测器联用实现低浓度样品的分析。化学发光检测由于其背景信号低而具有超高的灵敏度。毛细管电泳-化学发光检测联用方法将毛细管电泳的高效分离特性与化学发光检测的高灵敏性相结合,成为一种非常重要的分析方法,广泛用于化学分析、药物筛选以及环境监测等领域。该文对近年来毛细管电泳-化学发光检测联用方法的基本原理进行概述,并对其发展趋势和应用前景进行了展望。     

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

In this work, using benzo(a)pyrene (BaP) as marker, the analytical merits of on-line flow-injection cloud-point extraction (FI CPE), including preconcentration factor, extraction efficiency, sample throughput, and analysis time were evaluated by use of peroxyoxalate chemiluminescence (CL) detection. Moreover, by detailed discussion of several preconcentration conditions for traditional and on-line FI CPE the advantages of on-line FI CPE became conspicuously apparent. When coupled with separation techniques such as high-performance liquid chromatography (HPLC) or capillary electrophoresis (CE), on-line FI CPE–CL has much potential for analysis of low concentrations of polycyclic aromatic hydrocarbons (PAH) in environmental samples.     

无固定相分离-电感耦合等离子体质谱法在环境中痕量金属纳米颗粒分析中的应用

环境中金属纳米颗粒的分析检测不仅需要关注其浓度和化学组成,还需要对其形状、粒径和表面电荷等进行表征.此外,环境中金属纳米颗粒的分析需要解决其低赋存浓度以及复杂基质干扰的难题.无固定相分离技术与电感耦合等离子体质谱(ICP-MS)的在线联用,具有较强的颗粒分离能力和较低的元素检出限,能够快速准确地提供金属纳米颗粒的粒径分...     

Use of capillary electrophoresis with chemiluminescence detection for sensitive determination of homocysteine

A sensitive capillary electrophoresis (CE) method with chemiluminescence (CL) detection was developed for the determination of homocysteine (HCys) in human plasma. In this work, N‐(4‐aminobutyl)‐N‐ethylisoluminol was used as tagging reagent to label the analyte for achieving high assay sensitivity. N‐(4‐Aminobutyl)‐N‐ethylisoluminol‐tagged HCys after CE separation reacted with hydrogen peroxide in the presence of horseradish peroxidase, producing CL emission. Experimental conditions for labeling analyte, CE separation, and CL detection were studied. The CL intensity was proportional to the concentration of HCys in the range of 2.5×10^?8 to 5.0×10^?6 M. Detection limit (S/N=3) was 7.6×10^?9 M. Human plasma samples from healthy donors were analyzed by the presented method. HCys levels were found to be in the range of 9.50–15.3 μM.     

Advances and analytical applications in chemiluminescence coupled to capillary electrophoresis

The present review presents the state of the art of the developments, key strategies and analytical applications of chemiluminescence detection coupled to CE (CE‐CL). Different parts considering the most common CL systems have been included, such as the tris(2,2′‐bipyridine)ruthenium(II) system, the luminol and derivatives reaction, the peroxyoxalate CL or direct oxidations. New advances in homemade configurations and applications in different fields such as clinical, pharmaceutical, environmental and food analysis have been included. The focus is on studies which appeared from 2000 to the end of 2009.     

Determination of phenothiazines in pharmaceutical formulations and human urine using capillary electrophoresis with chemiluminescence detection

A CE instrument coupled with chemiluminescence (CL) detection was designed for the determination of promethazine hydrochloride (PTH) and promazine hydrochloride (PMH) in real samples. An important enhancement of the CL emission of luminol with potassium ferricyanide was observed in the presence of these phenothiazines; so this system was selected for their detection after CE separation. Parameters affecting the electrophoretic separation were optimized in a univariate way, while those affecting CL detection were optimized by means of a multivariate approach based on the use of experimental designs. Chemometrics was also employed for the study of the robustness of the factors influencing the postcolumn CL detection. The method allows the separation of the phenothiazines in less than 4 min, achieving LODs of 80 ng/mL for PMH and 334 ng/mL for PTH, using sample injection by gravity. Electrokinetic injection was used to obtain lower LODs for the determination of the compounds in biological samples. The applicability of the CE-CL method was illustrated in the determination of PTH in pharmaceutical formulations and in the analysis of PMH in human urine, using a previous SPE procedure, achieving an LOD of 1 ng/mL and recoveries higher than 85%.     

An on-column fracture/end-column reaction interface for chemiluminescence detection in capillary electrophoresis

Chemiluminescence (CL) offers a sensitive detection method for capillary electrophoresis (CE), but the implementation of CE–CL is usually under compromised operating conditions for CE, such as the prerequisite of extreme pH buffer for optimal CL reaction at the capillary outlet. This has sometimes significantly deteriorated the separation of CE. In this study, the development of a new interface makes it possible to optimize the operating conditions for CE separation and CL detection independently. The interface consists of an on-column fracture being installed in a reservoir near the capillary end to create an electrical connection and also serve as reagent addition entrance. The capillary terminal is inserted into an end-column reservoir for CL reaction and detection. In this arrangement, the applied electric field has been decoupled from the CL detection, which is proved to effectively improve CE's performance by allowing the use of optimal CE buffers. At the same time, it enables the optimization of CL detection independently. The applicability of this interface was evaluated by using acridinium ester (AE) and luminol systems. For AE system, the interfering products of CL reagent (⁻OH, HO₂⁻) have been prevented, and the pH range of CE buffer can be independent to the optimal pH value of AE CL reaction, which is usually below 3. The AE was detected using running buffer at pH 8.7, giving a detection limit of 0.1 nM (S/N = 3), and the theoretical plate numbers is as high as 56 000. The on-column fracture based configuration is simple, sensitive and easy to implement.     

聚(2-甲基-2-噁唑啉)在毛细管电泳分离蛋白质中的应用

毛细管电泳作为一种常见的液相分离技术,因其分析速度快、分离效率高、样品消耗量少等特点,在蛋白质分离分析领域有广泛应用。然而,常用的熔融硅毛细管容易吸附蛋白质,导致电渗流不稳定,分离结果重现性变差;此外,商用毛细管电泳中常用的紫外检测器由于光程短,使得毛细管电泳的检测灵敏度往往不能达到低丰度蛋白质的直接分析要求。因此寻找能够阻止蛋白质吸附、同时能够提高检测灵敏度的涂层是毛细管电泳分离分析蛋白质的重要课题之一。聚（2-甲基-2-噁唑啉）（PMOXA）作为一种类肽类亲水性聚合物,具有与抗蛋白质吸附聚合物聚乙二醇类似的亲水性、抗蛋白质吸附性和生物相容性,而且其类肽结构使之具有较聚乙二醇更好的稳定性,因此近年来在生物质传递、药物载体和阻抗蛋白质吸附等领域得到越来越多的应用。该文主要从两个方面对聚（2-甲基-2-噁唑啉）在毛细管电泳中的应用进行了阐述。一是利用多巴胺作为黏合层将其涂覆在毛细管内壁作为抗蛋白质吸附涂层,这种涂层不仅能成功分离多种蛋白质的混合物（如溶菌酶、细胞色素C、核糖核酸酶A和α-胰凝乳蛋白酶原A）,而且在定量检测奶粉中三聚氰胺、乳铁蛋白的过程中,能阻抗其他蛋白质的非特异性吸附,提高了毛细管电泳对奶粉中三聚氰胺、乳铁蛋白的检测效率。二是将其与具有刺激响应性的聚合物（如聚丙烯酸）构成二元混合刷涂层,在一定的pH和离子强度条件下,涂层可吸附目标蛋白质（如牛血清白蛋白、溶菌酶）,在另一pH和离子强度条件下可将吸附的目标蛋白质全部释放,同时在释放过程中,处于涂层表面的聚（2-甲基-2-噁唑啉）会进一步阻止蛋白质的吸附,释放的蛋白质在电渗流和电泳的双重作用下快速迁移,到达检测器的蛋白质瞬时浓度大大增加,使目标蛋白质得到富集,目标蛋白质的检测信号得到放大,从而达到了提高低丰度蛋白质检测灵敏度的目的。此外,该文还对聚（2-甲基-2-噁唑啉）在毛细管电泳分离蛋白质中的未来发展趋势进行了展望。     

Chemiluminescence detection in capillary electrophoresis using an ultra-fast co-catalyzed peroxyoxalate chemiluminescent reaction and electrokinetic reagent delivery

Summary Despite the impressive limits of detection and inherent selectivity afforded by peroxyoxalate chemiluminescence (POCL) detection, efficient coupling of POCL to capillary electrophoresis (CE) remains limited by the relatively slow kinetics of the reactions that drive imidazole-catalyzed chemiluminescence. Moreover, oxalate esters, used in POCL, are sparingly soluble in polar solvents and hydrolyze rapidly, presenting an additional challenge with respect to detection following aqueous phase separations. In this paper, a novel method for coupling an ultrafast POCL reaction to CE is presented. Post separation electrokinetic delivery of the POCL reagent bis(2,4,6-trichlorophenyl)oxalate (TCPO) was accomplished using a commercially available micro tee. Electrokinetic addition of TCPO allowed for precise control of the ratio of TCPO to the chemiluminescence (CL) reagents 1,2,2,6,6-pentamethylpiperidine (PMP) and 1,2,4-triazole (triazole), spiked into the running buffer. This novel method for CL reagent delivery avoided the problems and costs associated with using pressure or mechanical pumps to deliver reagents post separation. Use of this dual-component system (PMP and triazole) resulted in intense CL with half-lives of less than 2 seconds. Optimum conditions for CE-POCL detection were investigated using stopped-flow kinetics. The detection limit for 3-aminofluoranthene, following separation by CE, was<0.95 nM.     

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。     

A capillary electrophoresis detection scheme for underivatized amino acids based on luminol-BrO- chemiluminescence system

A novel chemiluminescence (CL) detection scheme has been developed for detecting underivatized amino acids following capillary electrophoresis (CE) separation. This detection was based on the inhibitory effect of amino acids on the CL reaction between luminol and BrO⁻ in alkaline aqueous solution. Detection of amino acids was accomplished with a borate-based background electrolyte at pH 9.2. The luminol was used as a component of the separation carrier electrolyte. Parameters affecting CE-CL separation and detection, such as the pH value, the concentration of electrolyte and CL reagent on the resolution were optimized. The relative standard deviation for the analysis of amino acids was less than 1.5% for the migration time and 4% for the peak height. The mass limits of detection were from 7 to 144 fmol for the 7 amino acids. This method has been applied of 7 amino acids in amino acid injection.     

Light‐emitting‐diode‐induced chemiluminescence detection for capillary electrophoresis

In this work, an LED‐induced‐chemiluminescence (LED‐CL) system was developed to extend the application of CL detection in CE. In the LED‐CL, the analyte photooxidizes luminol under the irradiation of LEDs and generates CL. Taking the advantage of the small size nature of LEDs, the constructed photoreactor is greatly miniaturized, and especially suitable as a CE detector. The feasibility of the proposed detector was evaluated by detection of riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) after CE separation. Under the optimized conditions, the LODs for RF, FMN and FAD were 0.007, 0.02 and 0.1 μg/mL, respectively, better than those by UV detection. The RSDs were 3.4, 3.6 and 4.1% for 0.5 μg/mL RF, 2 μg/mL FMN and 5 μg/mL FAD, respectively. The LED‐CL detector features low cost, miniaturization, fast response, high sensitivity and good reproducibility.     

Application of Capillary Electrophoresis for Determination of Inorganic Analytes in Waters

Aside from HPLC and GC, capillary electrophoresis (CE) is one of the most important techniques for high-performance separations in modern analytical chemistry. Its main advantages are the possibility of using different detection techniques, the possibility of in-capillary sample processing for preconcentration or derivatization, and ease of instrumental miniaturization down to the microfluidic scale. Those features are utilized in the separation of macromolecules in biochemistry and in genetic investigations, but they can be also used in determinations of inorganic ions in water analysis. This review, based on about 100 original research works, presents applications of CE methods in water analysis reported in recent decade, mostly regarding conductivity detection or indirect UV detection. The developed applications include analysis of high salinity sea waters, as well as analysis of other surface waters and drinking waters.     

毛细管电泳用于药物分析的研究进展

药物分析是毛细管电泳（CE）的重要应用领域,所有CE分离模式与检测方法都在各种药物及其不同形式样品的分离分析中显示出特色和应用能力。该文从药品分析领域中的小分子药物（包括手性药物）及其有关物质、中药与天然产物、体内药物分析、生物制品药物分析等几个方面,综述了近几年CE在这些传统药物分析领域应用的研究进展。限于篇幅,未包括现代药物分析研究比较活跃的理化常数测定、亲和毛细管电泳与结合常数研究（药物与受体间的相互作用等）、临床生物标志物分析、代谢组学和微流控芯片CE分析等方面的内容。根据目前传统药物分析领域的发展,该文关注到近期CE在顺应药物分析的法规需求、电容耦合非接触电导检测（CE-C⁴ D）、改进检测灵敏度与精密度、CE-十二烷基硫酸钠（SDS）毛细管电泳、全柱成像毛细管等电聚焦（icIEF）、抗体分析等方面的新进展。该文结合文献,讨论了目前传统药物分析领域的需求,以及CE在其中的地位、挑战和机遇。对目前CE主要作为互补分析方法在化学药和中药分析中的应用研究提出了一些针对性的建议,期待CE在生物制品分析中的特色和能力得到进一步的发挥,同时提出CE-MS和对CE分析重复性改进等新进展可能对未来CE应用领域的大幅度扩展。该综述主要涉及近3年（2017年1月到2020年2月）及部分2016年的相关文献。     

毛细管电泳新型手性分离体系研究进展

在现代分离科学中,手性化合物的分离分析一直是研究的重点和难点。相比于高效液相色谱（HPLC）、气相色谱（GC）等传统色谱分析方法,毛细管电泳（CE）技术凭借其高效率、低消耗、分离模式多样化等诸多优势,已经发展成为手性分离研究领域最有应用前景的分析方法之一。近年来,研究人员在CE手性分析方法的构建过程中,基于毛细管电动色谱（EKC）、配体交换毛细管电泳（LECE）、毛细管电色谱（CEC）等各种基础电泳模式,不断地对传统手性分离体系进行优化和改造,构建出了许多高性能的新型手性CE分离体系。如利用各类功能化离子液体以"手性离子液体协同拆分""手性离子液体配体交换""离子液体手性选择剂"等模式设计出多种基于离子液体的CE手性分离体系;利用纳米材料独特的尺寸效应、多样性、可设计性等特点,直接或与传统手性选择剂有机结合构建CE手性分离体系。此外,金属有机骨架材料修饰、低共熔溶剂修饰、非连续分段式部分填充等各式新颖的CE手性分离体系也都被研究人员成功开发,并表现出较大的发展潜力。该综述将对近年来（尤其是2015~2019年）此类新型CE手性分离体系的发展状况进行梳理,并结合相应的手性识别机理研究和手性CE方法实际应用情况,对该领域存在的问题及发展前景进行分析和展望。     

21世纪毛细管电泳技术及应用发展趋势

在21世纪，毛细管电泳技术面临着新的挑战和机遇，在其检测手段，仪器的小型化和集成化，以及分离模式上都存在着极大的发展空间，文中针对这三方面的发展趋势和毛细管电泳的应用进行了讨论。     

Recent advances of capillary electrophoresis in pharmaceutical analysis

This review covers recent advances of capillary electrophoresis (CE) in pharmaceutical analysis. The principle, instrumentation, and conventional modes of CE are briefly discussed. Advances in the different CE techniques (non-aqueous CE, microemulsion electrokinetic chromatography, capillary isotachophoresis, capillary electrochromatography, and immunoaffinity CE), detection techniques (mass spectrometry, light-emitting diode, fluorescence, chemiluminescence, and contactless conductivity), on-line sample pretreatment (flow injection) and chiral separation are described. Applications of CE to assay of active pharmaceutical ingredients (APIs), drug impurity testing, chiral drug separation, and determination of APIs in biological fluids published from 2008 to 2009 are tabulated.     

毛细管电泳和毛细管电色谱技术在农药残留检测中的应用

由于毛细管电泳（CE）和毛细管电色谱（CEC）具有所需样品体积小、分离效率高等特点,越来越多的学者已将它们应用到农药残留（简称农残）检测中,并将它们同各种不同的检测器以及样品浓缩方法相结合,以提高检测的灵敏度。本文对CE和CEC两种方法中所涉及的常见的样品预浓缩方法进行了简要的介绍。对各种不同类型的检测器（如紫外检测、荧光检测、电化学检测以及质谱检测等）的优缺点及其在农残检测中的应用情况进行了评述;同时对手性农药的CE和CEC分离检测情况进行了特别介绍;并对CE和CEC在农残分析与检测中的应用前景进行了展望。     

Capillary electrophoresis system with flow injection sample introduction and chemiluminescence detection on a chip platform

A capillary electrophoresis (CE) system with chemiluminescence (CL) detection was combined with flow injection (FI) sample introduction on a chip platform. A falling-drop interface was applied to perform FI split-flow sample introduction while achieving electrical isolation from the CE high voltage. A tubular reservoir at the capillary outlet served as both the CL reaction and detection cell for the luminol-peroxide-metallic ion chemiluminescent reaction, with the luminol included in the separation buffer and CL reagent H2O2 continuously introduced into the outlet reservoir. An optical fiber was positioned within the outlet reservoir directly opposite, and 300 microns away from, the capillary outlet for collecting and transferring the generated CL to the PMT. The peak height signals and the separation efficiency were almost independent of the reagent flow-rate, making the system a robust one. The performance of the system was illustrated by the separation of Co(II) and Cu(II), achieving baseline separation in 60 s. Detection limits (3 sigma) were 1.25 x 10(-8) and 2.3 x 10(-6) mol dm-3 for Co(II) and Cu(II), respectively. Peak height precision was 1.9% RSD (n = 9) at the 10(-7) mol dm-3 Co level.