Capillary Electrophoresis Chemiluminescence Detection Research Articles

Capillary electrophoresis-chemiluminescence detection for carcino-embryonic antigen based on aptamer/graphene oxide structure

A new strategy is proposed for determination of carcino-embryonic antigen (CEA) based on aptamer/graphene oxide (Apt/GO) by capillary electrophoresis-chemiluminescence (CE-CL) detection system. CEA aptamer conjugated with horseradish peroxidase (HRP) firstly mixes with GO, and the CL will be quenched because the stack of HRP–Apt on GO leads to chemiluminescence resonance energy transfer (CRET). When CEA exists, the specific combination of HRP–Apt and CEA can form HRP–Apt–CEA complex, which dissociates from GO. Then, the CL catalyzed by HRP–Apt–CEA complex can be detected without any CRET, and the content of CEA can be estimated by the CL intensity. It has been proved that the interference issue resulted from free HRP–Apt is solved well by mixing GO firstly with HRP–Apt, which blocks the free HRP–Apt's CL signal due to CL quenching effect of GO; and the interference resulted from GO to CL is also solved by CE, then the sensitivity and accuracy can be greatly improved. Results also showed that the CL intensity had a linear relationship with the concentration of CEA in the range from 0.0654 to 6.54ng/mL, and the limit of detection was approximately 4.8pg/mL (S/N=3). This proposed method with high specificity offers a new way for separation and determination of biomolecule, and has good potential in application of biochemistry and bioanalysis.

Electrophoresis–chemiluminescence detection of phenols catalyzed by hemin

Based on the catalytic activity of hemin, an efficient biocatalyst, an indirect capillary electrophoresis-chemiluminescence (CE-CL) detection method for phenols using a hemin-luminol-hydrogen peroxide system was developed. Through a series of static injection experiments, hemin was found to perform best in a neutral solution rather than an acidic or alkaline medium. Although halide ions such as Br(-) and F(-) could further enhance the CL signal catalyzed by hemin, it is difficult to apply these conditions to this CE-CL detection system because of the self-polymerization of hemin, as it hinders the CE process. The addition of concentrated ammonium hydroxide to an aqueous/dimethyl sulfoxide solution of hemin-luminol afforded a stable CE-CL baseline. The indirect CE-CL detection of five phenols using this method gave the following limits of detections: 4.8 × 10(-8) mol/L (o-sec-butylphenol), 4.9 × 10(-8) mol/L (o-cresol), 5.4 × 10(-8) mol/L (m-cresol), 5.3 × 10(-8) mol/L (2,4-dichlorophenol) and 7.1 × 10(-8) mol/L (phenol).

Determination of alkaloids inSinomenium acutumby field-amplified sample stacking in capillary electrophoresis with chemiluminescene detection

A simple and rapid capillary electrophoresis (CE) with an acidic potassium permanganate chemiluminescence (CL) detection method was developed to determine three alkaloids (curine, sinomenine and magnoflorine) simultaneously. A laboratory-built CE-CL detection interface was used. The field-amplified sample stacking technique was applied to the online concentration of alkaloids. Experimental conditions for CE separation and CL detection were investigated in detail to acquire optimum conditions. Under optimal conditions, the three alkaloids were baseline separated within 6 min, and the detection limits (S/N = 3) ranged from 0.03 µg/mL to 0.49 µg/mL. This method was successfully applied to determine the above three alkaloids in Sinomenium acutum, and the result of the determination of sinomenine was in good agreement with those given by high-performance liquid chromatography and CE methods. In addition, a possible CL reaction mechanism of sinomenine-KMnO4-H2SO4 was proposed.

Development and Evaluation of a Rotary Cell for Capillary Electrophoresis−Chemiluminescence Detection

Many efforts have been made toward the advancement of capillary electrophoresis chemiluminescence (CE-CL) detection and its applications through continuous development and improvement of interfaces. In this study, a novel rotary cell for CE-CL detection was fabricated and evaluated. A ring-shaped narrow channel with a quartz bottom is made in a cell body to hold CL reactants and act as the reaction chamber. The CE capillary is placed closely to the bottom of the reaction chamber where analyte is deposited into the CL reactants for reactions to occur. Detection is achieved with a photomultiplier tube below the reaction channel. An advantage of the rotary reaction cell is that it renews the reactants at the capillary end as it revolves at a preset speed during experiments. The rotary detection cell presents a new concept to the conventional coaxial-flow configuration by solving the problems of bubble formation and flow blockage that often interrupt the electrophoresis. Two standard proteins, horseradish peroxidase (HRP) and hemoglobin (Hb), were used to evaluate the interface's performance with luminol/H(2)O(2) CL system. Satisfactory sensitivities (LOD of 0.91 x 10(-9) M for HRP, and 4.37 x 10(-8) M for Hb at S/N = 3) were obtained in this proof-of-concept experiment. This novel design provides a straightforward and robust interface for CE-CL hyphenation.

Electrogeneration of Ferrate(VI) in Low-concentration NaOH Solution for Capillary Electrophoresis–Chemiluminescence Detection

Abstract A novel, eco-friendly, and stable homogeneous luminescent system for capillary zone electrophoresis (CE) detection was established, based on the chemiluminescence (CL) flash caused by mixing ferrate(VI) with luminol solution. It was found that the stable ferrate(VI) could be freshly electrogenerated in low-concentration NaOH solution for direct analytical application. To test this CL system, 8-hydroxyquinoline (HQ) was chosen as a model sample by CE detection.

Cover Picture: Electrophoresis 11'09

AbstractIssue no. 11 is a regular issue consisting of 22 research articles distributed over 5 parts including: (i) Proteins and Proteomics, (ii) EKC and CEC, (iii) Detection and Preconcentration Approaches, (iv) Enantioseparation and (v) Methodologies and Assays.Selected articles are:Quantifying Western blots: pitfalls of densitometry ((10.1002/elps.200800720))Light emitting diode‐induced chemiluminescence detection for capillary electrophoresis ((10.1002/elps.200800708))Double sample preconcentration by in‐line coupled large volume single drop microextraction and sweeping in capillary electrophoresis ((10.1002/elps.200800759))

Quantification of Carcinoembryonic Antigen by Capillary Electrophoresis–Chemiluminescence Detection using Internal Standard Method

Sensitive determination of tumor marker carcinoembryonic antigen (CEA) by capillary electrophoresis–chemiluminescence detection (CE-CL) has been developed using an internal standard method. Parameters affecting the CE separation and CL detection were systematically optimized. Under the optimal conditions, the free horseradish peroxidase (HRP)–labeled antibody (Ab*), the bound Ab*-antigen complex (Ab*-Ag), and HRP used as internal standard were well separated within 5 min. The proposed method was successfully applied for the quantification of CEA in human sera obtained from both healthy persons and patients.

Recent Advances in Chemiluminescence Detection for Capillary Electrophoresis

Abstract Miniaturization, integration, and automation in analytical chemistry are a clear trend. In this article, we present a review of the miniaturization, integration, and automation in chemiluminescence detection for capillary electrophoresis with 65 references.

On-capillary Chemiluminescence Detection for Capillary Electrophoresis with a Single Capillary

On-capillary chemiluminescence detection for capillary electrophoresis with a single capillary was reported. A hole (about 30 microm diameter) was made on the capillary wall at about 50.5 cm from the inlet end. Hydrogen peroxide solution could enter the capillary from the hole, and mixed with luminol and copper(II) to produce chemiluminescence. The chemiluminescence was detected by a PMT under the hole. Several factors that influenced chemiluminescence intensity were investigated. The detection limits for luminol and N-(4-aminolbutyl)-N-ethylisoluminol (ABEI) were 1 x 10(-11) and 2 x 10(-10) mol L(-1), respectively. The method features simple construction and no dead volume.

Monitoring the reaction of hemoglobin with hydrogen peroxide by capillary electrophoresis-chemiluminescence detection

The reaction of hemoglobin (Hb) with hydrogen peroxide (H 2O 2) leads to fluorescent product and heme degradation. We applied capillary electrophoresis-chemiluminescence (CE-CL) detection to monitor the course of Hb reacting with H 2O 2. Hb and released free iron ion (Fe 3+) were detected based on their enhancement effects on CL of the luminol-H 2O 2 system. In this study, we discovered an intermediate of this reaction which intensely enhances the luminol-H 2O 2 CL system. The ratio of max CL signals of Fe 3+, Hb and this intermediate is circa 1:10:60.

Enhancing Effect of Phenylboronic Acid Compounds and Their Interactions with the Diol Groups of Saccharides in a Capillary Electrophoresis-Chemiluminescence Detection System

In our previous study, we proposed molecular recognition of mono- and disaccharides making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis with a chemiluminescence detection system. Here, to extend our knowledge of molecular recognition, we first examined the enhancing effects of four phenylboronic acid compounds other than p-iodophenylboronic acid i.e., 4-biphenylboronic acid, 4-octyloxyphenyl-boronic acid, 3-octyloxyphenylboronic acid, and 4-dodecyloxyphenylboronic acid, for luminol-hydrogen peroxide-horseradish peroxidase reaction in the capillary electrophoresis-chemiluminescence detection system. Only 4-biphenylboronic acid showed an enhancing effect similar to that of p-iodophenylboronic acid; the effect was determined over the range of 0.5-10 microM in this system. Second, we estimated the apparent stability constants between the diol groups of saccharides (1-methyl-D-glucoside, D-saccharose, and D-fructose) and the boronic acid moieties of the two enhancers, p-iodophenylboronic acid and 4-biphenylboronic acid. The apparent binding constants obtained here provided insight to confirm the principle of molecular recognition for the saccharides examined here.

Capillary electrophoresis-chemiluminescence detection system equipped with a consecutive sample-injection device.

We have developed a consecutive sample-injection device for capillary electrophoresis, which comprises one four-way cock, two syringe pumps, and an interface part taking advantage of two three-way Teflon joints. Sample introduction into the capillary is made hydrodynamically by pressure, caused by the flow of the sample solution at the tip of the capillary inlet. We combined the injection device with a capillary electrophoresis-chemiluminescence detection system. A mixture solution of N-(4-aminobutyl)-N-ethylisoluminol, isoluminol isothiocyanate, and luminol was analyzed as a model sample by the present system. The sample solution was consecutively injected and detected with about a 230 s interval. The present capillary electrophoresis-chemiluminescence detection system with the consecutive sample injection device features easy and rapid operation, an inexpensive apparatus, high sensitivity, as well as consecutive analysis.

Capillary Electrophoresis of Polyamines with Universal Indirect Chemiluminescence Detection, Using Cobalt (II) as a Probe Ion

Highly sensitive indirect chemiluminescence detection for capillary electrophoresis (CE) of polyamines was demonstrated in this paper. In the indirect chemiluminescence (CL) detection system, a strong and stable background CL signal can be generated by the luminol‐hydrogen peroxide reaction catalyzed by cobalt (II) probe ion in the running buffer. Displacement of the cobalt (II) probe ion in the running buffer, by migrating polyamine cations, results in a decrease in the background signal. Some factors affecting the separation of polyamines, such as buffer pH, buffer concentration, and additives, were systematically investigated using a commercial CE instrument with an in‐house‐built CL detector. Under the optimal conditions, three polyamines, putrescine (PUT), spermidine (SPD), and spermine (SPM) were well separated in less than 4.5 min. The detection limits of the concentration for PUT, SPD, and SPM were 1.0 × 10−8, 5 × 10−9, and 1.2 × 10−8 mol/L (S/N = 3), respectively. This sensitivity is about three orders better than that in the UV detection, and is almost the same as in the laser induced fluorescence detection. Our data further demonstrated that CE with indirect CL detection was a powerful tool for analysis of organic cations.

Ultrasensitive chemiluminescence detection of aM vanadium(IV) by capillary electrophoresis

Ultrasensitive chemiluminescence (CL) detection of aM vanadium(IV) in capillary electrophoresis (CE) is first reported. In this work, inclusion of the luminol in the electrophoretic carrier electrolyte avoids the loss of light signal that occurs when luminol and hydrogen peroxide are mixed in advance, as in the conventional method in CE–CL detection. The detection limit (S/N ratio=3) for V(IV) is 2.4×10 −17 M (24 aM), which has been improved by a factor of 10 4 as compared with that of the most sensitive metal ion detection (Co 2+ 0.5 pM) reported previously. In addition, the separation of V(IV) and V(V) has been performed successfully.

Sensitive and universal indirect chemiluminescence detection for capillary electrophoresis of cations using cobalt(II) as a probe ion.

Highly sensitive and universal indirect chemiluminescence detection for capillary electrophoresis of cations was described. This novel method is based on use of the ultrasensitive cobalt(II) as a probe ion in the running buffer. A strong and stable background chemiluminescent signal can be generated by the luminol-hydrogen peroxide reaction catalyzed by cobalt(II) ion. Displacement of the cobalt(II) probe ion in the running buffer by a migrating sample cation results in a quantifiable decrease in the background signal. The conditions for electrophoresis and the chemiluminescent reaction were systematically investigated using a commercial capillary electrophoresis instrument with an in-house-built chemiluminescence detector. Under the optimal conditions, the detection limits of the concentration for manganese(II), cadmium(II), nickel(II), lead(II), and 14 lanthanides were (3.0-6.0) x 10(-9) mol/L (S/N = 3), which was approximately 3 orders of magnitude better than indirect UV detection and 2 orders better than indirect laser-induced fluorescent detection. A mixture of 18 metal ions including 14 lanthanides was efficiently separated within 3.5 min using lactate to partially complex the metal ions. Our data demonstrated that CE with indirect CL detection was a powerful and universal tool for analysis of inorganic and organic cations.

Improvement of a capillary electrophoresis-chemiluminescence detection system for using a polyacrylamide-coated capillary.

Improvement of a capillary electrophoresis-chemiluminescence detection system for using a polyacrylamide-coated capillary.

Immunoassay Using Chemiluminescence Detection of Dyestuff-Containing Liposomes as a Labeling Reagent

A new immunoassay using chemiluminescence detection of dyestuff-containing liposomes as a labeling reagent is proposed. Human serum albumin labeled with Eosin Y containing-liposomes was employed as a labeling reagent for an immunoassay. After the immune reaction was carried out in the presence of an antibody-immobilized glass bead, the reactant solution was subjected to the capillary electrophoresis–chemiluminescence detection system. That is, the bound/free separation was conducted by use of glass beads, also, other coexisting compounds which might influence chemiluminescence detection were easily separated from the labeled human serum albumin by capillary electrophoresis. The labeled human serum albumin in the reactant solution was detected with high sensitivity. The amount of the labeled human serum albumin showed a good relationship to that of human serum albumin as an analyte through immune reaction. Human serum albumin could be determined over the range of 1 × 10−6 − 5 × 10−4 M. The present method was also applicable to the determination of protein in a serum sample without being interfered with by coexisting constituents.

Determination of morphine, oripavine and pseudomorphine using capillary electrophoresis with acidic potassium permanganate chemiluminescence detection.

A simple and robust capillary electrophoresis chemiluminescence detection system for the determination of morphine, oripavine and pseudomorphine is described, based upon the reaction of these analytes with acidic potassium permanganate in the presence of sodium polyphosphate. The reagent solution was contained in a quartz detection cell which also held both the capillary and the anode. The resultant chemiluminescence was monitored directly using a photomultiplier tube mounted flush against the base of the detection cell. To ensure that no migration of the permanganate anion occurred, the anode was placed at the detector end whilst the electroosmotic flow was reversed by the addition of hexadimethrine bromide (0.001% m/v) to the electrolyte. The three analytes were separated counter to the electroosmotic flow via their interaction with alpha-cyclodextrin. The methodology realised detection limits (3 x S/N) of 2.5 x 10(-7) M for both morphine and oripavine and 5 x 10(-7) M for pseudomorphine. The relative standard deviations of the migration times and the peak heights for the three analytes ranged from 0.6 up to 0.8% and from 1.5 up to 2.1%, respectively.

Microchip capillary electrophoresis using on-line chemiluminescence detection

Chemiluminescence detection was used in capillary electrophoresis integrated on a microchip. Quartz microchips have two main channels and four reservoirs. Dansyl-lysine and -glycine were separated and detected with bis[(2-(3,6,9-trioxadecanyloxycarbony)-4-nitrophenyl]oxalate as peroxyoxalate chemiluminescent reagent. These dansyl amino acids came into contact with the chemiluminescence reagent to produce visible light at the interface between the separation channel and chemiluminescence reagent-containing reservoir. The detection limit ( S/N=3) for dansyl-lysine was 1·10 −5 M, which corresponded to the very small mass detection limit of ca. 0.4 fmol. However, the concentration sensitivity in the present system was approximately two orders of magnitude lower than that in the conventional capillary electrophoresis–chemiluminescence detection system. The relative standard deviations of migration time and peak height for dansyl-lysine were 4.2 and 4.5%, respectively. A channel conditioning before every run and an appropriate control of voltages were needed for the reproducible results. The present system had advantages in rapid separation time (within 40 s), small (several 10 pl) and accurate sample injection method using a cross-shaped injector, and simplification and miniaturization of the detection device.

On-line chemiluminescence detection for capillary electrophoresis based on the reaction of barium peroxide with luminescence reagents

On addition of trace amounts of luminol or lucigenin to the milligram amounts of barium peroxide (BaO 2) solid powder, strong chemiluminescent phenomena have been observed. Based on this observation, a novel on-line solid-phase chemiluminescence detector was designed for capillary electrophoresis. A 27 cm×75-μm I.D. column with a 0.3-cm length detection window was used. A small amount of BaO 2 powder was packed into the detection window section. After the separation of luminol, lucigenin and N-(4-aminobutyl)- N-ethylisoluminol (ABEI), the analytes may be detected on-line. The optimum conditions for the capillary electrophoresis separation and detection were investigated. The detection limits were 5×10 −8, 7×10 −8 and 1×10 −8 mol/l for lucigenin, ABEI and luminol, respectively. The proposed method was also used for the separation and detection of two amino acids labeled with ABEI.