Determination of Tramadol in Human Serum by Capillary Electrophoresis with the End-Column Electrochemiluminescence Detection

A capillary electrophoresis (CE) coupled with end-column electrochemiluminescence (ECL) detection method for the analysis of tramadol (TMD) has been investigated. ECL detection was working electrode biased at 1.2 V in a 20mmol·L-1 sodium phosphate buffer (pH = 8.0) containing 5 mmol·L-1 Ru (where bpy = 2,2’-bipyridyl). Linear correlation (r ≥ 0.997) between ECL intensity and drug concentration was obtained in the range 3 × 10-4 - 6 × 10-6 mol·L-1. The limits of detection (LODs) for tramadol in water was 3.012 × 10-8 mol·L-1(S/N = 3). The relative standard deviation values on peak size (10-5 mol·L-1 level) and migration time for the tramadol were 4.58% and 1.39% (n = 10), respectively. Applicability of the CE-ECL method to the analysis of human serum spiked with tramadol was

Highly-sensitive electrochemiluminescence biosensor for detection of inosine monophosphate in meat based on graphdiyne/AuNPs/luminol nanocomposites

Inosine monophosphate(IMP),as a critical umami substance,is one of the most important indicators for evaluating the quality of meat products.Here,a sensitive electrochemiluminescence(ECL)biosensor based on graphdiyne(GDY)/AuNPs/luminol nanocomposites was constructed to detect IMP.The GDY/AuNPs/luminol nanocomposites were synthesized by using simple one-pot method.GDY utilized its 2D framework to disperse and fix gold nanoparticles,which inhibited the agglomeration of gold nanoparticles and greatly improved its stability and catalytic properties.Importantly,GDY/AuNPs/luminol nanocomposites showed excellent catalytic ability and superior ECL activity towards luminol-H_(2)O_(2) systems due to the synergistic effect of GDY and AuNPs.Under optimal conditions,the prepared biosensor exhibited a wide linear range from 0.01 g/L to 20 g/L,a satisfactory limit detection of 0.0013 g/L,as well as an excellent specificity.Moreover,we carried out the precise analysis of IMP in actual meat samples with acceptable results compared to the liquid chromatography.We believe that this work could offer an efficient ECL platform for accurate and reliable report of IMP levels,which is significant for maintaining food quality and safety.

Advances of Electrochemical and Electrochemiluminescent Sensors Based on Covalent Organic Frameworks

Covalent organic frameworks(COFs),a rapidly developing category of crystalline conjugated organic polymers,possess highly ordered structures,large specific surface areas,stable chemical properties,and tunable pore microenvironments.Since the first report of boroxine/boronate ester-linked COFs in 2005,COFs have rapidly gained popularity,showing important application prospects in various fields,such as sensing,catalysis,separation,and energy storage.Among them,COFs-based electrochemical(EC)sensors with upgraded analytical performance are arousing extensive interest.In this review,therefore,we summarize the basic properties and the general synthesis methods of COFs used in the field of electroanalytical chemistry,with special emphasis on their usages in the fabrication of chemical sensors,ions sensors,immunosensors,and aptasensors.Notably,the emerged COFs in the electrochemiluminescence(ECL)realm are thoroughly covered along with their preliminary applications.Additionally,final conclusions on state-of-the-art COFs are provided in terms of EC and ECL sensors,as well as challenges and prospects for extending and improving the research and applications of COFs in electroanalytical chemistry.

An electrochemiluminescent magneto-immunosensor for ultrasensitive detection of hs-cTnI on a microfluidic chip

Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix has become an important area of research.For example,the detection of high-sensitivity cardiac troponin I (hs-cTnI) is strongly recommended in clinical guidelines for early diagnosis of acute myocardial infarction.Based on the use of an electrode modified by single-walled carbon nanotubes (SWCNTs) and a Ru(bpy)32+-doped silica nanoparticle (Ru@SiO2)/tripropylamine (TPA) system,a novel type of electrochemiluminescent (ECL) magnetoimmunosensor is developed for ultrasensitive detection of hs-cTnI.In this approach,a large amount of[Ru(bpy)3]2+is loaded in SiO2(silica nanoparticles) as luminophores with high luminescent efficiency and SWCNTs as electrode surface modification material with excellent electrooxidation ability for TPA.Subsequently,a hierarchical micropillar array of microstructures is fabricated with a magnet placed at each end to efficiently confine a single layer of immunomagnetic microbeads on the surface of the electrode and enable 7.5-fold signal enhancement In particular,the use of transparent SWCNTs to modify a transparent ITO electrode provides a two-order-of-magnitude ECL signal amplification.A good linear calibration curve is developed for hs-cTnI concentrations over a wide range from 10 fg/ml to 10 ng/ml,with the limit of detection calculated as 8.720 fg/ml (S/N=3).This ultrasensitive immunosensor exhibits superior detection performance with remarkable stability,reproducibility,and selectivity.Satisfactory recoveries are obtained in the detection of hs-cTnI in human serum,providing a potentia analysis protocol for clinical applications.

Capillary electrophoresis with electrochemiluminescence detection for the analysis of quinolone drugs and pharmacokinetics study

A novel method for the determination of two quinolone drugs norfloxacin （NOR） and levofloxacin （LVX） was described by capillary electrophoresis with electrochemiluminescence detection. The good relationship （r ≥ 0.9991） between peak area and concentration of analytes was established over two orders of magnitude. The limits of detection （LOD, S/N = 3） in standard solution are 4.8 × 10^-7 mol/L for NOR and 6.4 × 10^-7 mol/L for LVX, respectively. The limits of quantitation （LOQ, S/N = 10） in real human urine samples are 1.2 × 10^-6 mol/L for NOR and 1.4 × 10^-6 mol/L for LVX, respectively. The present method was successfully applied to the determination of NOR and LVX in human urine and the studv of oharmacokinetics of NOR.

Solid-state electrochemiluminescence of a novel iridium(Ⅲ) complex

The solid-state ECL behavior of a water-insoluble bis-cyclometalated （pq）2Ir（N-phMA） complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/（pq）2Ir（N-phMA） film, MWNTs/Ru（bpy）3^2＋ film and （pq）2Ir（N-phMA） directly modified glassy carbon electrode were fabricated; only the MWNTs/（pq）2Ir（N-phMA） film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.

Photoluminescence and electrochemiluminescence studies of chosen rare earths systems

Eu（Ⅲ） complexes with chosen Keggin polyoxomatalates, POM, containing organic counter cations （tetrabutylarnmonium, tetrabutylphosphonium, triphenylethylphosphonium）, were synthesized, and their photophysical properties were studied. The synthesized complexes had the general formula of XnH5-n[EuSiW11O39], formulated based on the results of elemental and thermogravimetric analysis and FTIR spectroscopy. The photophysical properties of the obtained compounds were investigated using photoluminescence and electrochemiluminescence, ECL, methods in solutions and solids. The most intense luminescence of Eu（Ⅲ） was observed for the complexes with tetrabutylarnmonium cations. After the addition of phenanthroline to the XnH5-n[EuSiW11O39] solutions, a large increase in the Eu（Ⅲ） luminescence intensity and a lengthening of its luminescence lifetime were observed as a result of the formation of ternary complexes. Attempts to apply ECL as a method of light emission by generating species capable of forming excited states in Ln/POMs, i.e., Tb（Ⅲ） and Eu（Ⅲ） in the Na9EuW10O36 and Na9TbW10O36 complexes, were made. The influence of the POM complexes on the ECL was also tested using the Tb/EDDHA （EDDA=ethylenediamine di（o-hydroxyphenylacetic acid）） complex, which is effective in generating ECL.

Spectral analysis in ultraweak emissions of chemi-and electrochemiluminescence systems

Investigation of ultraweak emissions in the processes of chemiluminescence, CL, and electrochemiluminesce, ECL, requires special techniques of their recording and spectral analysis. From among the hitherto proposed methods of detection of the emission spectra of these processes, that of the cut-off filter was most sensitive. The usefulness of this method in interpretation of the CL and ECL systems of the quantum yields in the range 1×10^-9-1×10^-11 containing ions and complexes of Eu（Ⅲ）, Tb（Ⅲ） and Dy0ID was shown. Exceptional character of the emission bands of lanthanide ions, being a result of the f-f electron transitions and in particular their low FWHM, permitted the appli- cation of the cut-off filter method to their analysis. The results obtained for CL and ECL on the basis of analysis of ultraweak emission proved to be successful in analytical applications. The systems containing Eu（Ⅲ） ions hydrated or complexed with organic ligands enabled inferring changes in the coordination sphere of the ions.

Detection of telomerase activity by combination of telomeric repeat amplification protocol and electrochemiluminescence assay

A highly sensitive telomerase detection method that combines telomeric repeat amplification protocol （TRAP） and magnetic beads based electrochemiluminescence （ECL） assay has been developed. Briefly, telomerase recognizes biotinylated telomerase synthesis primer （B-TS） and synthesizes extension products, which then serve as the templates for PCR amplification using B-TS as the forward primer and tris-（2′2′-bipyridyl） ruthenium （TBR） labeled ACX （TBR-ACX） as the reversed primer. The amplified product is captured on streptavidin-coated paramagnetic beads and detected by ECL. Telomerase positive HeLa cells were used to validate the feasibility of the method. The experimental results showed down to 10 cancer cells can be detected easily. The method is a useful tool for telomerase activity analysis due to its sensitivity, rapidity, safety, high throughput, and low cost. It can be used for screening a large amount of clinical samples.

An On-line Galvanic Cell Generated Electrochemiluminescence and Flow Injection Determination of Calcium in Milk and Vegetable

An on-line Ag/Al galvanic cell is investigated and employed to generate electrochemiluminescence (ECL). The potential of the galvanic cell could be adjusted by varying the components of flow reagent. The cell performed perfect capability of supplying a stable potential for ECL generation. Based on the weak ECL of calcein blue could be greatly sensitized by the presence of calcium in alkaline solution, calcium contents in milk samples and in cabbage were assayed and the results were compared with those from ICP-AES method.

An improved electrochemiluminescence polymerase chain reaction method for the detection of Fusarium wilts

An improved electrochemiluminescence polymerase chain reaction （ECL-PCR） method was developed and applied to detect Fusarium wilt. Briefly, the internal transcribed spacer （ITS） sequence of Fusarium oxysporumf, sp Cubense （FOC） was amplified by PCR. Two universal fragments, which were complimentary to Ru（bpy）3^2＋ （TBR） labeled probe and Biotin labeled probe, respectively, were connected to the tail of primers so that all the PCR products got universal sequences. Then biotin labeled probes and TBR labeled probes were hybridized with the PCR products at the same time. Through the specific interaction between biotin and streptavidin, the PCR products were captured by streptavidin coated magnetic bead and then detected by ECL assay. The experiment results showed that the healthy banana samples and infected ones can be discriminated by this ECL-PCR method. This improved ECL-PCR approach is useful in Fusarium wilt detection due to its high sensitivity, simplicity and stability.

Determination of Amino Acids by Ru(bpy)_3^(2+) Cathodic Electrochemiluminescence with High Sensitivity

The unique cathodic electrochemiluminescence（ECL） emission of Ru（bpy）3^2＋（bpy=2,2′-bipyridine） was observed via Nation film at Au electrode[Au/Nafion/Ru（bpy）3^2＋] at about 0.20 V（vs. Ag/AgCl） and applied to the determination of several amino acids without prior derivatization with high sensitivity. The cathodic electrochemiluminescence（ECL） exhibits the detection limits and linear ranges of several amino acids comparable to or better than those of capillary electrophoresis with conventional ECL detection method（at 1.10-1.20 V vs. Ag/AgCl） based on precolumn derivatization. The results suggest that the cathodic ECL is promising for the detection of amino acids in bioanalysis.

Enantiomeric Separation of Antidepressant Trimipramine by Capillary Electrophoresis Combined with Electrochemiluminescence Detection in Aqueous-organic Media

The antidepressant trimipramine（Tri） enantiomers were successfully separated by capillary electrophoresis（CE） coupled with electrochemiluminescence（ECL） detection in aqueous-organic media. A dual cyclodextrin（CD） system combining β-CD and hydroxypropyl-β-cyclodextrin（HP-β-CD） was used as chiral selector. Acetonitrile（ACN） was added to the running buffer to improve the separation efficiency, detection sensitivity and repeatability. The method was also successfully applied to the chiral separation of Tri in spiked human urine sample.

A Kind of Electrode Enhanced the Electrochemiluminescence

Three kinds of platinum electrodes with different geometry were designed. The relation of the electrochemiluminescence (ECL) intensity with the geometry of these electrodes has been investigated. The optical character of these electrodes was directly studied by observation of ECL image and measurement of the ECL intensity. The results showed that the ECL not only concentrated on the edge of the electrode but also concentrated on the edge of holes, which contain in the electrode. The ECL intensity from Ru(bpy)3Cl2·6H2O on round electrode was about half of that on four-hole round disk electrode for a same concentration of Ru(bpy)3Cl2·6H2O, so the detection limit was improved to 10-18 mol/L Ru(bpy)3Cl2·6H2O on four-hole round disk electrode, three times higher than that on round disk electrode.

Tris(2,2'-bipyridyl)ruthenium(Ⅱ) electrochemiluminescence (ECL) enhanced by rutin on platinum electrode

Ru（bpy）3^2＋ electrochemiluminescence （ECL） was applied to determination of rutin. ECL intensity of Ru（bpy）3^2＋ could be enhanced in the presence of rufin in basic solution on platinum electrode. At pH 9.9, light emission intensity was found to be linear with rutin in the range of 1-50μmol/L.

Allele-specific amplification and electrochemiluminescence method for single nucleotide polymorphism analysis

A new approach combined the specificity of allele-specific amplification （ASA） with the sensitivity of electrochemiluminescence （ECL） assay for single nucleotide polymorphism （SNP） analysis was proposed. Briefly, target gene was amplified by a biotin-labeled allele-specific forward primer and a Ru（bpy）3 ^2＋（TBR）-labeled universal reverse primer. Then, the amplicon was captured onto streptavidin-coated paramagnetic beads through biotin label, and detected by measuring the ECL signal of TBR label. Different genotypes were distinguished according to the ECL values of the amplicons by different genotypic primers. K-ras oncogene was used as a target to validate the feasibility of the method. The experiment results show that the different genotypes can be clearly distinguished by ASA-ECL assay. The method is useful in SNP analysis due to its sensitivity,safety, and simplicity.

Determination of Trace Molybdenum in Plant Seeds by Electrochemiluminescence Method

[ Objective] This study aimed to establish an electrochemiluminescence method for determining the trace molybdenum in plant seeds. [ Method ] The equipment used in this study consisted of an electrogenerated reagent system and a flow-injection chemiluminescence detection system. The optimal electric poten- tial, reagent acidity, flow rate of sample solution, as well as the concentration and alkalinity of luminal were screened to measure the trace molybdenum in plant seeds. [ Result I The unstable molybdenum （III） was on-line electrogenerated from molybdenum （VI） via controlled potential electrolysis technique using a home- made flow-through carbon electrolytic cell at the potential of -0.60 V （vs Ag/AgC1）. The method allowed the determination of 5.0 × 10-10 _ 5.0 ×10-7 g/ml mo- lybdenum with a detection limit of 5 × 10 u g/ml molybdenum （VI）. The relative standard deviation was 2.6% for the 1.0 × 10 -9 g/ml molybdenum solution in 11 measurements. [ Conclusion] Compared with the previous methods, this electrochemilum^nescence method not only improved the selectivity of the determina- tion, but also avoided the use of toxic reagent mercury.

Capillary electrophoresis coupled with electrochemiluminescence for determination of cloperastine hydrochloride

Objective To investigate the electrochemiluminescence (ECL) behavior of cloperastine hydrochloride. Methods ECL intensity of tris (2,2′-bipyridyl) rutheniumo(Ⅱ) was enhanced, the method for the determination of cloperastine hydrochloride was established using capillary electrophoresis (CE) coupled with electrochemilumolinescence (ECL) detection. Results Under the optimum conditions, ECL intensity varied linearly with cloperastine hydrochloride concentration from 7.0×10-6g/mL to 1.0×10-4g/mL. The detection limit (S/N=3) was 8.05×10-7g/mL. The relative standard deviation of the ECL intensity and the migration time for 11 consecutive injections of 1.0×10-5g/mL cloperastine hydrochloride was 2.9% and 1.5%, respectively. This method was successfully applied to cloperastine hydrochloride tablet determination. Conclusion The method has been established, validated and applied for determination of cloperastine hydrochloride.

Determination of Trace Silver( Ⅰ ) in Basic Aqueous Solution by Electrochemiluminescence of a New Reagent 6-(2-Hydroxy-4-Diethylaminophenylazo)-2,3-Dihydro-1,4-Phthalazine-1,4-Dione

The electrochemiluminescence (ECL) of a new reagent 6- (2-hydroxy- 4 diethy laminophenylazo)-2,3-dihydro-1 ,4-phthalazine-1,4-dione (HDEA) in a basic aqueous so lution was studied by using the apparatus designed by ourselves. Trace amounts of silver ( Ⅰ ) shows a significant effect on the efficiency of light emission of HDEA during a positive trigonometrical wave pulse was exerted on the solution. The linear relationship between the light intensity and the concentration of silver( Ⅰ ) occurs in the range of 5. 0×10-8 to 3. 0×10-8 mol/L Ag(Ⅰ ) in a medium of KOH-KCl-HDEA (pH= 12. 8). The detection limit of the method is 2. 0×10-8 mol/LAg( Ⅰ ), and the r. s. d. for 1.0×10-7 mo)/L Ag ( Ⅰ ) is 5%. Of 21 metal ions concerned, only nickel( Ⅱ ), cerium( Ⅳ ) and cobalt( Ⅱ ) interfere the silver detection seriously; Ⅰ and Br also have some interference.