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Analytica Chimica Acta (v.541, #1-2)
Chemiluminescence methods for the determination of ofloxacin by Paul S. Francis; Jacqui L. Adcock (pp. 3-12).
Ofloxacin is a synthetic fluoroquinolone antibiotic that has been used in the treatment of respiratory tract, urinary tract and tissue-based infections. Methodology for the determination of ofloxacin based on chemiluminescence detection can be divided into: direct oxidation with tris(2,2′-bipyridyl)ruthenium(III) or permanganate; and enhancement of the emission from either the oxidation of sulfite or the reaction between sodium nitrite and hydrogen peroxide. In this paper, we compare the analytical methodology and evaluate the light-producing pathways that have been proposed for these reactions.
Keywords: Ofloxacin; Fluoroquinolones; Flow-injection analysis; Chemiluminescence spectra
Analytical applications of peroxyoxalate chemiluminescence by Makoto Tsunoda; Kazuhiro Imai (pp. 13-23).
Coupled with high-performance liquid chromatography (HPLC), flow injection analysis or capillary electrophoresis, peroxyoxalate chemiluminescence (POCL) reaction was proved to be a useful, selective and sensitive detection system for the analytes including hydrogen peroxide, native fluorescent compounds and fluorescent derivatized compounds. Its application to quantitation of polycyclic aromatic hydrocarbons (PAHs) and catecholamines has afforded tremendous benefit in the field of environmental and clinical sciences. This review covers the reports on the analytical application of POCL reaction from the late 1970s to the most recent.
Keywords: Peroxyoxalate chemiluminescence; High-performance liquid chromatography; Flow injection analysis; Hydrogen peroxide; Catecholamines
Bio- and chemiluminescence imaging in analytical chemistry by Aldo Roda; Massimo Guardigli; Patrizia Pasini; Mara Mirasoli; Elisa Michelini; Monica Musiani (pp. 25-35).
Bio- and chemiluminescence imaging techniques combine the high sensitivity of bio- and chemiluminescence detection with the ability of current light imaging devices to localize and quantify light emission down to the single-photon level. These techniques have been successfully exploited for the development of sensitive analytical methods relying on the evaluation of the spatial distribution of the light emitted from a target sample. In this paper, we report on recent applications of bio- and chemiluminescence imaging for in vitro and in vivo assays, including: quantitative assays performed in various analytical formats, such as microtiter plates, microarrays and miniaturized analytical devices, used in the pharmaceutical, clinical, diagnostic and environmental fields; luminescence imaging microscopy based on enzymatic, immunohistochemical and in situ hybridization reactions for the localization of metabolites, enzymes, antigens and gene sequences in cells and tissues; whole-body luminescence imaging in live animals for evaluating biological and pathological processes and for pharmacological studies.
Keywords: Bioluminescence; Chemiluminescence; In vivo imaging; Low-light imaging
Recent developments and applications of chemiluminescence sensors by Zhenyu Zhang; Sichun Zhang; Xinrong Zhang (pp. 37-46).
This is a brief review on the developments and applications of chemiluminescence (CL) sensors dated from 1999 to present. Methods and materials for immobilization of CL reagents are introduced. The CL-based sensors, including the sensors for the detection of inorganic species, organic species and biological macromolecules are summarized. The advantages and limitations of CL sensors are discussed.
Keywords: Chemiluminescence sensor; Immobilized reagents; Inorganic and organic species; Nucleic acid; Drug; Antibody; Protein
Sol–gel-immobilized Tris(2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence sensor for high-performance liquid chromatography by Han Nim Choi; Sung-Hee Cho; Yu-Jin Park; Dai Woon Lee; Won-Yong Lee (pp. 47-54).
The sol–gel-immobilized Tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)32+] electrogenerated chemiluminescence (ECL) sensor was applied to the reversed-phase high-performance liquid chromatography (HPLC) determination of phenothiazine derivatives (promazine, chlorpromazine, triflupromazine, thioridazine, and trifluoperazine) and erythromycin in human urine samples. In this method, Ru(bpy)32+ was immobilized in sol–gel-derived titania (TiO2)–Nafion nanocomposite films coated on a dual platinum electrode. This method eliminates an extra pump needed for the delivery of Ru(bpy)32+ reagent into a reaction/observation zone in front of photomultiplier tube because the immobilized-Ru(bpy)32+ is recycled on the electrode surface by an applied potential at +1.3V versus Ag/AgCl (3M NaCl) reference electrode. The resulting analytical performances such as detection limit, working range, sensitivity, and measurement precision were slightly worse than those obtained with the conventional post-column Ru(bpy)32+ addition approach. The lack of significant interferences and the low detection limits for phenothiazine derivatives and erythromycin indicate that the proposed HPLC-Ru(bpy)32+ ECL detection method is suitable for the determination of those compounds in biological fluids.
Keywords: Tris(2,2′-bipyridyl)ruthenium(II); Electrogenerated chemiluminescence; Sol–gel; Phenothiazines; Erythromycin; HPLC
Potentials of multisyringe flow injection analysis for chemiluminescence detection by Manuel Miró; José Manuel Estela; Víctor Cerdà (pp. 55-66).
In this paper, multisyringe flow injection analysis (MSFIA) is presented as a powerful and promising tool for automated liquid-phase chemiluminescence (CL) assays. The capability of operation under discontinuous forward flow regime while handling minute, well-defined volumes of sample and reagents in a multicommuted format offers unrivalled analytical features. As opposed to the parent flow injection (FI) and sequential injection (SI) analysis, CL reactions with divergent pH and kinetic demands can be easily implemented in a single protocol sequence, as demonstrated in the bulk of the text via luminol-based methods. MSFIA is proven extremely suitable for accommodating enzymatic CL assays in a renewable fashion by exploiting soluble enzymes, with no need for the typical immobilization procedures used in FI and SI systems. Solid-phase CL sensors have also gained full advantage of the benefits of MSFIA. In this context, a novel optosensor devised for on-line monitoring of trace levels of orthophosphate is described. Similar configurations are proposed for the selective and sensitive determination of metals, Vitamins, nutrients and saccharides in environmental and biological samples as well as beverages, which denotes the versatility of this automated flow technique. Special emphasis is also given to the simple instrumental set-up, including a dedicated flow-through luminometer, arranged for a multitude of CL assays.
Keywords: Multisyringe flow injection analysis; Chemiluminescence; Automation
Flow injection chemiluminescent determination of N-nitrosodimethylamine using photogenerated tris(2,2′-bipyridyl) ruthenium (III) by Tomás Pérez-Ruiz; Carmen Martínez-Lozano; Virginia Tomás; Jesús Martín (pp. 67-72).
A flow injection configuration was developed and evaluated for the chemiluminescent determination of N-nitrosodimethylamine. The method is based on the on-line cleavage of the NNO bond of the nitrosamine by irradiation with ultraviolet light. The dimethylamine generated was subsequently reacted with tris(2,2′-bipyridyl) ruthenium (III), which was generated through the on-line photo-oxidation of tris(2,2′-bipyridyl) ruthenium (II) with peroxydisulfate.After selecting the best operating parameters, the emitted light showed a linear relationship with the concentration of N-nitrosodimethylamine between 1.5 and 148ngml−1, with a detection limit of 0.29ngml−1. The repeatability was 1.6% expressed as relative standard deviation ( n = 10) and the reproducibility, studied on five consecutive days, was 3.2%. The sample throughput was 50 injections per hour. The method was applied to studying the recoveries of N-nitrosodimethylamine in water and different cured meat products.
Keywords: Nitrosamines; Chemiluminescence; Flow-injection; Tris(2,2′-bipyridyl) ruthenium (III) photogenerated
Electrochemiluminescent determination of methamphetamine based on tris(2,2′-bipyridine)ruthenium(II) ion-association in organically modified silicate films by Changqing Yi; Yin Tao; Bo Wang; Xi Chen (pp. 73-81).
Tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMe–DiMOS) were used as co-precursor to immobilize poly( p-styrenesulfonate) (PSS), then tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+) was successfully immobilized on a glass carbon electrode via ion-association. The immobilized Ru(bpy)32+ shows good electrochemical and photochemical activities. Electrochemical and electrochemiluminescence (ECL) characterizations of the organically modified silicates (ORMOSILs) modified film electrodes were made by means of cyclic voltammetry and chronocoulometry. The ORMOSIL films were investigated by atomic force microscopy, scanning electrochemical microscope, tunnelling electrochemical microscope, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and fluorescence spectroscopy. XPS in-depth profiles revealed a homogeneous distribution of Ru(bpy)32+ inside the silica thin layers. The modified electrode was used for the ECL determination of methamphetamine (METH) and showed high sensitivity. Detection limit was 2.0 × 10−7moll−1 for METH (S/N = 3) with a linear range from 5.0 × 10−7 to 1.0 × 10−3moll−1 ( R = 0.986). The relative standard deviation ( n = 6) was 1.1% for the determination of 1.0 × 10−5moll−1 METH. Furthermore, the Ru(bpy)32+ immobilized modified electrode was applied in the ECL determination of methamphetamine (METH) in scout cases.
Keywords: Ru(bpy); 3; 2+; Sol–gel; Electrochemiluminescence; Modified electrode; Methamphetamine
Hot electron-induced electrogenerated chemiluminescence of SYBR® Green I by Pirita Laakso; Hannamari Anttila; Veli Kairisto; Jarkko Eskola; Sakari Kulmala; Timo Ala-Kleme (pp. 83-87).
Hot electrons can be injected from conductor/insulator/electrolyte (C/I/E) junctions into an aqueous electrolyte solution. Injected hot electrons induce electrogenerated chemiluminescence (ECL) of various luminophores in fully aqueous solutions. Such ECL gives the basis of electrochemiluminoimmunoassays and DNA-probe assays where different luminophores can be used as electrochemiluminescent labels. This work shows that SYBR® Green I is suitable as an ECL label in detection methods based on C/I/E tunnel-emission electrodes such as oxide-coated aluminium, magnesium and silicon electrodes.
Keywords: Electrochemiluminescence; Electrogenerated chemiluminescence; SYBR; ®; Green I; Hot electron; Tunnel junction conductor/insulator/electrolyte electrodes
Luminol chemiluminescence induced by immobilised xanthine oxidase by Shahanara Banu; Gillian M. Greenway; R. Alan Wheatley (pp. 89-95).
The properties of xanthine oxidase, immobilised on controlled-pore glass, were investigated and applied in assays for hypoxanthine and superoxide dismutase. Phosphate buffer (pH 7.8) was passed through a glass reactor packed with immobilised enzyme, immediately mixed with 1.0×10−4M luminol in carbonate buffer at pH 10.0 and CL measured. CL was enhanced 14-fold by EDTA and 57-fold by Fe(II)–EDTA. For soluble enzyme, injected into a similar FIA manifold, CL was enhanced to a lesser extent either by iron(II) or EDTA or iron(II)–EDTA. CL is enhanced more using dialysed enzyme than with crude enzyme. CL signals are initially high due to rapid reaction between iron(II) and oxygen, but the steady emission used for measurement results from the superoxide-driven Fenton reaction, generating hydroxyl radicals that oxidise luminol which then reacts with enzymatically produced superoxide.The calibration for hypoxanthine was linear ( r2=0.9834, n=7) up to 17μM: CL/mV=0.0371[HX]/μM−0.0142. The R.S.D. ( n=4) was 1.69% at 8.24μM and the apparent Km≥16μM, ≥12× greater for immobilised enzyme than for the soluble xanthine oxidase. The chemiluminescence decreased with increased superoxide dismutase (SOD) concentration (IC50=1.2μgml−1 and detection limit=0.25μgml−1) and it was shown to decrease to a lesser extent for catalase.
Keywords: Abbreviations; CPG; controlled pore glass; SOD; superoxide dismutase; XO; xanthine oxidase; AMP; aminophthalate; CL; chemiluminescenceXanthine oxidase; Luminol chemiluminescence; Superoxide dismutase
Molecular imprinting–chemiluminescence sensor for the determination of brucine by Mei Liu; Jiuru Lu; Yunhua He; Jianxiu Du (pp. 97-102).
The brucine-imprinted polymer was synthesized and the binding characteristic of the imprinted polymer to brucine was evaluated by equilibrium binding experiments. Using the imprinted polymer as recognition material, a new chemiluminescence (CL) sensor for the determination of brucine was developed based on the CL reaction of brucine with potassium permanganate in acidic medium. The sensor displayed high selectivity and high sensitivity. The linear response range of the sensor was from 5.0×10−9 to 1.0×10−6g/mL ( r=0.9981) and the detection limit was 2×10−9g/mL. The relative standard deviation for the determination of 1.0×10−7g/mL brucine solution was 2.6% ( n=9). The sensor was applied to the determination of brucine in urine samples with satisfactory results.
Keywords: Brucine; Chemiluminescence; Molecular imprinted polymer; Sensor
Flow injection chemiluminescence determination of tetracycline by Alan Townshend; Wirat Ruengsitagoon; Chalermporn Thongpoon; Saisunee Liawruangrath (pp. 103-109).
A simple flow injection chemiluminometric method for the determination of tetracycline (TC), chlortetracycline (CTC) or oxytetracycline (OTC) has been developed. The method is based on the chemiluminescence (CL) produced the reduction by these tetracyclines of tris(2,2′-bipyridyl)ruthenium(III). The latter is obtained by oxidation of tris(2,2′-bipyridyl)ruthenium(II) by potassium permanganate in dilute nitric acid. A standard or sample solution is injected into the ruthenium(II) stream either before or after it has merged with the potassium permanganate stream. The CL intensity is increased by the presence of manganese(II). Under the optimum conditions, calibration graphs were obtained for 5×10−5 to 5×10−4moll−1 of each tetracycline. The detection limits ( s/ n=3) were 2.0×10−6, 1.9×10−6 and 1.0×10−6moll−1, respectively, and mid-calibration range standard deviations were not greater than 3.7% ( n=10). The method was successfully applied to the determination of these drugs in pharmaceutical formulations with a sample throughput of 50h−1.
Keywords: Chemiluminescence; Tetracycline; Oxytetracycline; Chlortetracycline; Flow injection; Ruthenium(II)
A new strategy for the chemiluminescent screening analysis of total N-methylcarbamate content in water by Jorge Juan Soto-Chinchilla; Laura Gámiz-Gracia; Ana M. García-Campaña; Luis Cuadros-Rodríguez (pp. 111-116).
A new procedure for the screening of total N-methylcarbamate (NMCs) content in water at different concentration levels is here presented. It is based on a previous off-line alkaline hydrolysis of the NMCs, for the production of methylamine (MA), and its subsequent derivatisation with o-phthalaldehyde (OPA). After that, the obtained derivative is involved in the peroxyoxalate chemiluminescent (PO-CL) reaction using imidazole as a catalyst being the CL emission proportional to the total NMC content. The chemiluminescent reaction is carried out in a flow injection analysis (FIA) manifold, employing sodium dodecyl sulphate micellar medium as carrier, which avoids the rapid degradation of POs in water solution. The applicability of the screening method is shown for the monitoring of NMCs in natural waters. Analytical features, as specification limit signal, screening uncertainty, sensitivity and specificity, are calculated.
Keywords: Screening analysis; N; -Methylcarbamates; Chemiluminescence; Flow injection analysis
Detection of pyrrolizidine alkaloids using flow analysis with both acidic potassium permanganate and tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence by Bree A. Gorman; Neil W. Barnett; Richard Bos (pp. 117-122).
For the first time, analytically useful chemiluminescence was elicited from the reactions of the pyrrolizidine alkaloids. Heliotrine, retronecine, supinine, monocrotaline and echinatine N-oxide yielded chemiluminescence upon reaction with tris(2,2′-bipyridyl)ruthenium(II) whilst lasiocarpine, its N-oxide and supinine elicited light upon reaction with acidic potassium permanganate. Detection limits for heliotrine were 1.25×10−7M and 9×10−9M for tris(2,2′-bipyridyl)ruthenium(III) perchlorate with flow injection analysis (FIA) and the silica-immobilised reagent (4-[4-(dichloromethylsilanyl)-butyl]-4′-methyl-2,2′-bipyridine)bis(2,2′-bipyridyl)ruthenium(II) with sequential injection analysis (SIA), respectively. Lasiocarpine was detectable at 1.4×10−7M using acidic potassium permanganate with FIA. Additionally, the silica-immobilised reagent was optimised with respect to the oxidant (ammonium ceric nitrate) concentration and the aspiration times which afforded a detection limit for codeine of 5×10−10M using SIA.
Keywords: Pyrrolizidine alkaloids; Chemiluminescence; Immobilised tris(2,2′-bipyridyl)ruthenium(II); Sequential injection
Flow injection chemiluminescence determination of dobutamine hydrochloride injection using luminol–ferricyanide/ferrocyanide system by Haiyan Liu; Ling Zhang; Jingming Zhou; Yuhong Hao; Pingang He; Yuzhi Fang (pp. 123-127).
It was found that the weak chemiluminescence produced from the reaction of dobutamine hydrochloride with luminol in alkaline solution could be strongly enhanced by potassium ferricyanide and potassium ferrocyanide. Based on this found, a new flow injection chemiluminescence method is proposed for the determination of dobutamine hydrochloride. Under the optimum conditions, the proposed method has a linear range of 1.0×10−10 to 1.0×10−7gml−1, with a detection limit of 2.6×10−11gml−1 for dobutamine hydrochloride (3 σ). A complete analysis could be performed in 40s including washing and sampling, giving a throughout of about 90h−1. The relative standard deviation (R.S.D.) for 11 parallel measurements of 1.0×10−8gml−1 dobutamine is 1.23%. The proposed method has been applied for the determination of dobutamine hydrochloride in its pharmaceutical formulations. The results obtained compared well with those by an official method. The possible mechanism of this chemiluminescence reaction was also proposed.
Keywords: Chemiluminescence; Flow injection; Dobutamine hydrochloride
Chemiluminescence determination of nitrogen oxide in air with a sequential injection method by Yang Wang; Shi-Hua Fan; Shi-Li Wang (pp. 129-134).
A chemiluminescence (CL) method coupled to sequential injection was described for the determination of trace amount of nitrogen oxide in air. The flow cell and holding coil was combined in which the flow cell was as a part of holding coil, which make it easy to track CL reaction for the sequential injection analytical system. Triehanolamine (TEA) solution was used to absorb nitrogen dioxide in air and then converted into nitrite. Nitride reacts with hydrogen peroxide to form peroxynitrous acid in sulfuric acid medium, which is subsequently quenched into peroxynitrite in basic solution and accompanied with CL reaction. Uranine and ethyldimethylcetylammonium bromide were used to enhance the CL intensity during the decomposition of peroxynitrite. The detection limit (3 σ) of 1×10−7M was obtained for 50μl sample. Nitrogen oxide can be determined in the linear range of 1×10−7–1×10−4M with correlation coefficient of 0.9999. The relative standard deviation (R.S.D.) for 11 repeated measurements of 1×10−5M NO2− was 2.7%. The sampling frequency was 80samples/h, and the recoveries were 85–104%.
Keywords: Sequential injection; Chemiluminescence; Nitrogen oxide
Electrochemiluminescence of Tb(III) chelates at optically transparent tunnel emission electrodes fabricated by atomic layer deposition by M. Håkansson; M. Helin; M. Putkonen; Q. Jiang; M. Kotiranta; J. Suomi; A.J. Niskanen; T. Ala-Kleme; S. Kulmala (pp. 135-139).
Atomic layer deposition was used to fabricate optically transparent tunnel emission electrodes for the purpose of generating electrogenerated chemiluminescence from aromatic Tb(III) chelates. Y2O3-coated aluminium-doped ZnO glass working electrodes proved to be suitable for injecting hot electrons into the electrolyte solution during cathodic pulse-polarisation of the electrode. Observed cathodic emission at these electrodes was clearly based on5D4→7FJ radiative transitions of Tb(III) and calibration curves of Tb(III) chelates at these electrodes were found to be linear over several orders of magnitude of concentration down to subnanomolar levels when emission was monitored at 545nm by a photon counting detector and using time-resolved detection.
Keywords: Atomic layer deposition; Tunnel emission electrodes; Hot electrons; Electrogenerated chemiluminescence; Tb(III); Bioaffinity assays
Electrogenerated chemiluminescence (ECL) 79. by Jai-Pil Choi; Allen J. Bard (pp. 141-148).
Hydrogen peroxide (H2O2) can be used as a coreactant to generate reductive-oxidation ECL of Tris(2,2′-bipyridine)ruthenium(II), Ru(bpy)32+ (bpy=2,2′-bipyridine), in pH 7.5 phosphate buffer solution (PBS). Although Ru(bpy)3+ is adsorbed and precipitated on the electrode upon reduction of Ru(bpy)32+ in aqueous solutions, ECL can still be generated and scanning electrochemical microscopy (SECM) experiments verified the presence of some dissolved Ru(bpy)3+ in the solution. When H2O2 is electrochemically reduced, it produces hydroxyl radical (OH). ECL is generated by an energetic electron transfer (ET) reaction between Ru(bpy)3+ andOH. The ECL intensity depends on both the Ru(bpy)32+ and H2O2 concentrations. However, a relatively high concentration of H2O2 (>1mM H2O2 with 0.1mM Ru(bpy)32+) quenches ECL significantly. H2O2 also quenches the photoluminescence of Ru(bpy)32+ with a quenching rate constant of 5.7×106M−1s−1.
Keywords: Tris(2,2′-bipyridine)ruthenium(II); Hydrogen peroxide; Electrogenerated chemiluminescence (ECL); Coreactant; Hydroxyl radical; Quencher
Development of a sensitive flow injection-chemiluminescence detection method for the indirect determination of propranolol by George Z. Tsogas; Dimitrios V. Stergiou; Athanasios G. Vlessidis; Nicholaos P. Evmiridis (pp. 149-155).
A highly sensitive flow injection-chemiluminescence detection (FI-CL) method based on pyrogallol (Pg) chemiluminescent reagent (CL-reagent) oxidized by periodate for the determination of propranolol is presented. The presented method is an indirect CL detection method based on the CL emission generated during the oxidation of Pg with the excess of periodate that remains after oxidation of propranolol within the time period of 10min. The obtained propranolol calibration curve is linear up to 1.0mgl−1 with a sensitivity of −0.95Vmg−1l. At higher than 1.0mgl−1 propranolol concentrations the propranolol calibration curve is still linear up to 20.0mgl−1 with a sensitivity of −0.05Vmg−1l. The detection limit is restricted from the noise level and at S/N=3 was found to be 37.4μgl−1 (3.74ng) with R.S.D.%=0.34 for seven replicate measurements.
Keywords: Propranolol determination; Chemiluminescence detection; Flow injection analysis; Pyrogallol; Periodate
Cathodic electrogenerated chemiluminescence of Ru(bpy)32+ chelate at oxide-coated heavily doped silicon electrodes by Qinghong Jiang; Johanna Suomi; Markus Håkansson; Antti J. Niskanen; Miia Kotiranta; Sakari Kulmala (pp. 157-163).
High amplitude cathodic pulse polarization of ultra thin oxide film-coated heavily doped silicon electrodes induces tunnel emission of hot electrons into aqueous electrolyte solution, which probably results in the generation of hydrated electrons in the vicinity of the electrode surface. The method allows the detection of tris (2,2′-bipyridine) ruthenium(II) chelate at subnanomolar concentration level. This paper shows that both n- and p-type heavily doped silicon electrodes can be used, illustrates the effect of oxide film thickness upon the silicon electrode on the intensity of ECL of tris (2,2′-bipyridine) ruthenium(II) and discusses the basic features of tris (2,2′-bipyridine) ruthenium(II) chelate-specific ECL at these electrodes. Thin oxide film-coated silicon electrodes provide a lower blank emission and a higher ECL intensity of the present ruthenium chelate than oxide-covered aluminium electrodes. This suggests that thin oxide film-coated silicon is a very promising working electrode material, especially in microanalytical systems made fully or partly of silicon.
Keywords: Electrogenerated chemiluminescence; Hot electrons; Ultra thin silicon dioxide films; Tunnel emission; Ru(bpy); 3; 2+; chelate; Labels
Time-resolved detection of electrochemiluminescence of luminol by Johanna Suomi; Markus Håkansson; Qinghong Jiang; Miia Kotiranta; Mika Helin; Antti J. Niskanen; Sakari Kulmala (pp. 165-167).
The luminescence lifetime of the electrochemiluminescence of luminol was studied at oxide-coated silicon and aluminum electrodes. In an undivided cell, the ECL was found to be produced only by cathodic processes, and luminol could be detected down to picomolar levels with time-resolved measurements.
Keywords: Time-resolved electrochemiluminescence; Luminol; Insulating film-coated electrodes; Silicon electrodes; Aluminum electrodes
Direct current-induced electrogenerated chemiluminescence of hydrated and chelated Tb(III) at aluminum cathodes by M. Håkansson; Q. Jiang; A.-M. Spehar; J. Suomi; M. Kotiranta; S. Kulmala (pp. 169-175).
Cathodic DC polarization of oxide-covered aluminum produces electrogenerated chemiluminescence from hydrated and chelated Tb(III) ions in aqueous electrolyte solutions. At the moment of cathodic voltage onset, a strong cathodic flash is observed, which is attributed to a tunnel emission of hot electrons into the aqueous electrolyte solution and the successive chemical reactions with the luminophores. However, within a few milliseconds the insulating oxide film is damaged and finally dissolved due to (i) indiffusion of protons or alkali metal ions into the thin oxide film, (ii) subsequent hydrogen evolution at the aluminum/oxide interface and (iii) alkalization of the electrode surface induced by hydrogen evolution reaction. When the alkalization of the electrode surface has proceeded sufficiently, chemiluminescence is generated with increasing intensity. Aluminum metal, short-lived Al(II), Al(I) or atomic hydrogen and its conjugated base form, hydrated electron, can act as highly reducing species in addition to the less energetic heterogeneously transferred electrons from the aluminum electrode. Tb(III) added as a hydrated ion in the solution probably luminesces in the form of Tb(OH)3 or Tb(OH)4− by direct redox reactions of the central ion whereas multidentate aromatic ligand chelated Tb(III) probably luminesces by ligand sensitized chemiluminescence mechanism in which ligand is first excited by one-electron redox reactions, which is followed by intramolecular energy transfer to the central ion which finally emits light.
Keywords: Chemiluminescence; Electrogenerated luminescence; Lanthanide (III) chelates; Aluminum; Difficult reductions; Determination of sulfate; Determination of peroxodisulfate
Ruthenium(II) tris(2,2′-bipyridine) chelate as a chemiluminophore in extrinsic lyoluminescences of aluminium and magnesium in aqueous solution by Qinghong Jiang; Miia Kotiranta; Kaarina Langel; Johanna Suomi; Markus Håkansson; Anna-Maria Spehar; Timo Ala-Kleme; Jarkko Eskola; Sakari Kulmala (pp. 177-184).
Ruthenium(II) tris(2,2′-bipyridine) chelate shows chemiluminescence (CL) both during dissolution of metallic aluminium in alkaline conditions, and during dissolution of magnesium metal in acidic conditions. The presence of peroxodisulfate ions strongly enhances the CL. Magnesium system provides considerably better detectability of the present chelate giving linear calibration plot spanning over many orders of magnitude of concentration down to subnanomolar concentration levels. The possible primary species generated and luminescence mechanisms are shortly discussed.
Keywords: Chemiluminescence; Generation of free radicals; Al(I); Al(II); Hydrated electron; Sulfate radical; Mg(I); Hydrogen atom; Oxyradicals
Flow-injection chemiluminescence determination of meloxicam by oxidation with N-bromosuccinimide by Haiyan Liu; Ling Zhang; Yuhong Hao; Qingjiang Wang; Pingang He; Yuzhi Fang (pp. 185-190).
A rapid and sensitive flow-injection chemiluminescence method is described for the determination of meloxicam based on its reaction with N-bromosuccinimide (NBS) in alkaline medium. Under the optimum conditions, the proposed method allows the measurement of meloxicam over the range of 2.2×10−7 to 2.8×10−5mol/l with a detection limit of 7.7×10−8mol/l. The relative standard deviation for 11 parallel measurements of 2.8×10−6mol/l meloxicam is 2.14%. The method has been applied satisfactorily to the determination of meloxicam in pharmaceutical preparations. The results agree well with those obtained by spectrophotometry. The mechanism of the chemiluminescence reaction is briefly explained with spectroscopic evidence.
Keywords: Chemiluminescence; Flow-injection; N; -Bromosuccinimide; Meloxicam
Investigation of RuBPS–Ce(IV) chemiluminescence reaction and its application in determination of two diuretics by Juan Xi; Xinghu Ji; Shaohong Zhang; Xinping Ai; Zhike He (pp. 191-196).
The chemiluminescence mechanism of tris-(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)ruthenium(II) (RuBPS)–Ce(IV) system and the effects of two diuretics, hydrochlorothiazide and furosemide, on its chemiluminescence intensity were investigated in detail. It was found that each of the two diuretics could enhance the chemiluminescence emission intensity of RuBPS–Ce(IV) system, based on which, they were sensitively detected by chemiluminescence analysis, respectively. Under the optimum experimental conditions, the linear range and detection limit of hydrochlorothiazide were 2.5×10−3 to 6.0×10−1μgml−1 and 1.0×10−3μgml−1, respectively; those of furosemide were 1.0×10−2 to 4.0μgml−1 and 8.8×10−3μgml−1, respectively. The proposed method has been applied to analyze the pharmaceuticals with satisfied results.
Keywords: Tris-(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)ruthenium(II); Chemiluminescence; Hydrochlorothiazide; Furosemide
Comparison and development of two different solid phase chemiluminescence ELISA for the determination of albumin in urine by Lixia Zhao; Jin-Ming Lin; Zhenjia Li (pp. 197-205).
Two chemiluminescence enzyme-linked immunosorbent assay (ELISA) methods based on avidin–biotin system and Fluorescein-iso-thiocyanate (FITC)-anti-FITC system as two different solid phase for the determination of albumin in urine were optimized, characterized and compared. Avidin or anti-FITC antibody was coated in the microplates to provide a universal solid phase which improved the variability and sensitivity. Alkaline phosphatase (ALP) labeled albumin and albumin from standard or patient samples compete for biotinylated-antibody or FITC labeled antibody binding sites. Enzyme activity in the bound fraction was detected with the chemiluminescence substrate 4-methoxy-4-(3-phosphatephenyl)-spiro-(1,2-dioxetane-3,2′-adamantane) (AMPPD). The influence of several physico-chemical parameters, such as incubation time, detergent concentration and solid phase conditions were also studied. For the two solid phase, both the linear range and the limit of detection of albumin were 0.15–15 and 0.089μg/mL, compared with the commercially ELISA kit, a good correlation were obtained. Moreover, three different solid phases include avidin–biotin system, FITC–anti-FITC system and the anti-albumin Ab directly coated the microtitre plates were compared mainly from the cost and precision, the results showed: (1) when the avidin–biotin system as solid phase, the amounts of the antibody used was only the 1/10 than those of the anti-FITC antibody as solid phase and antibody directly coated the microtiter plates; (2) the C.V. of these two solid-phase CL ELISA methods were lower than that of antibody directly coated solid phase.
Keywords: Albumin; Avidin–biotin system; FITC–anti-FITC system; Solid phase; CL-ELISA