Homogeneous chemiluminescence system in neutral and near neutral aqueous solution with ClO2 as oxidant and its analytical application

Using ClO₂ as chemiluminescence (CL) oxidant, a novel homogeneous CL system in neutral and near neutral aqueous solution is proposed in this paper. ClO₂ could oxidize sulfite in pH 5.0–8.5 acetate buffer to produce CL emission, and pipemidic acid could sensitize the CL system. The ClO₂–SO₃²⁻–pipemidic acid reaction was used as a model CL system and explored the possibility of highly active and eco-friendly ClO₂ being used as CL oxidant in neutral and near neutral aqueous solution. Combined with flow-injection analysis, the proposed CL system was applied to the automated dissolution testing of pipemidic acid tablet. Compared with the common strong acidic or strong basic CL system, this proposed CL owns its advantages.     

Silver nanoparticle-initiated chemiluminescence reaction of luminol-AgNO3 and its analytical application

Ag⁺ has been regarded as an inert chemiluminescent oxidant. In this work, it was found that in the presence of silver nanoparticles (AgNPs), AgNO₃ could react with luminol to produce strong chemiluminescence (CL). The AgNPs with smaller size could initiate stronger CL emission. To investigate the CL mechanism of the AgNPs–luminol–AgNO₃ system, the UV–visible spectra and the CL spectrum of the CL system were obtained. The CL reaction mechanism involving catalysis was proposed. Compared with the reported nanoparticles–luminol–H₂O₂ CL system, the AgNPs–luminol–AgNO₃ CL system has the advantages of low background and good stability. Moreover, the new CL system was used in immunoassay for IgG.     

Synthesis and characterization of the SO(2)N(3)(-), (SO(2))(2)N(3)(-), and SO(3)N(3)(-) anions

SO(2) solutions of azide anions are bright yellow, and their Raman spectra indicate the presence of covalently bound azide. Removal of the solvent at -64 degrees C from CsN(3) or N(CH(3))(4)N(3) solutions produces yellow (SO(2))(2)N(3)(-) salts. Above -64 degrees C, these salts lose 1 mol of SO(2), resulting in white SO(2)N(3)(-) salts that are marginally stable at room temperature and thermally decompose to the corresponding azides and SO(2). These anions were characterized by vibrational and (14)N NMR spectroscopy and theoretical calculations. Slow loss of the solvent by diffusion through the walls of a sealed Teflon tube containing a sample of CsSO(2)N(3) in SO(2) resulted in white and yellowish single crystals that were identified by X-ray diffraction as CsSO(2)N(3).CsSO(3)N(3) with a = 9.542(2) A, b = 6.2189(14) A, c = 10.342(2) A, and beta = 114.958(4) degrees in the monoclinic space group P2(1)/m, Z = 2, and Cs(2)S(2)O(5).Cs(2)S(2)O(7).SO(2), respectively. Pure CsSO(3)N(3) was also prepared and characterized by vibrational spectroscopy. The S-N bond in SO(2)N(3)(-) is much weaker than that in SO(3)N(3)(-), resulting in decreased thermal stability, an increase in the S-N bond distance by 0.23 A, and an increased tendency to undergo rotational disorder. This marked difference is due to SO(3) being a much stronger Lewis acid (pF(-) value of 7.83) than SO(2) (pF(-) value of 3.99), thus forming a stronger S-N bond with the Lewis base N(3)(-). The geometry of the free gaseous SO(2)N(3)(-) anion was calculated at the RHF, MP2, B3LYP, and CCSD(T) levels. The results show that only the correlated methods correctly reproduce the experimentally observed orientation of the SO(2) group.     

The (SO2)2N3- anion

The recently proposed (SO2)2N3- anion was structurally characterized by single-crystal X-ray diffraction of the [Cs][(SO2)2N3] salt (P2(1)/c, a = 8.945(2) A, b = 10.454(2) A, c = 8.152(2) A, beta = 109.166(3) degrees, Z = 4, and R1 = 0.0329 at 130 K). In the (SO2)2N3- anion, both SO2 ligands are coordinated to one terminal nitrogen atom of the N3- anion.     

Enhanced fluorescence of 3-(naphthalene-2-ylimino)-1-phenylbutan-1-one-Tb with 1,10-phenanthroline ternary system and its analytical application

A new Schiff base ligand: 3-(naphthalene-2-ylimino)-1-phenylbutan-1-one (NPB) was synthesized. Its fluorescence intensity with terbium(III) was greatly enhanced by the addition of 1,10-phenanthroline (Phen) in the chloroform solution. The mechanism of fluorescence enhancement was studied. The results indicate the formation of a ternary NPB-Phen-Tb complex. In the ternary system, Phen can transfer the energy absorbed by Phen and NPB to Tb(3+).     

Three-component synthesis of 3-(diarylmethyl)indoles using Fe(ClO4)3/SiO2 as catalyst

Russian Journal of Organic Chemistry - Three-component reaction of indole, aromatic aldehyde, and N,N-dimethyl aniline in the presence of silica-supported Fe(ClO4)3 as catalyst afforded the...     

A new chemiluminescence system: MnO(-)(4)-Na(2)CO(3)-KOH and its application in the determination of manganese

A new, fast and simple inorganic chemiluminescence method for the determination of trace amounts of manganese is described. When MnO(-)(4) is injected into 0.40M Na(2)CO(3)-0.70M KOH mixed solution in a reaction cell, the strong chemiluminescence occurs and is recorded. The detection limit is 0.1 ppb Mn and the linear range extends from 0.1 to 10 ppb Mn. A 5-ppb Mn concentration can be determined with a relative standard deviation of 5.6% (15 replicates). The commonly encountered cations do not interfere with the determinations. This method has been successfully applied to the direct determination of manganese in bauxite. The reaction mechanism is also briefly discussed.     

Flow-injection chemiluminescence determination of chlortetracycline using on-line electrogenerated [Cu(HIO(6))(2)](5-) as the oxidant

A novel chemiluminescence (CL) flow system for the determination of chlortetracycline is described. It is based on the direct CL reaction of chlortetracycline and [Cu(HIO₆)₂]⁵⁻ in KOH medium. The unstable [Cu(HIO₆)₂]⁵⁻ was on-line electrogenerated by constant-current electrolysis. The CL intensity was linear with chlortetracycline concentration in the range of 0.1–100 μg ml⁻¹. The determination limit was 5.3×10⁻⁸ g ml⁻¹. The whole process could be completed in 1 min. The proposed method is suitable for automatic and continuous analysis, and has been applied satisfactorily to analysis of chlortetracycline in biological fluid.     

Flow-injection chemiluminescence study of Ce(IV)-Na2SO3-Tb(III)-fluoquinolone antibiotic system with DNA

A novel flow injection chemiluminescence (CL) system is developed to determine DNA. According to the fact that DNA linearly quenches the CL intensity of Ce(IV)-Na(2)SO(3)-Tb(III)-fluoquinolone antibiotic (FLUQ) system, DNA concentration is determined. The calibration graphs are linear in the range of 0.04-10 microg/ml (for both natural and denatured DNA), and the 3sigma limits of detection are 7.8 ng/ml (natural DNA) and 9.5 ng/ml (denatured DNA). According to fluorescence spectrum and CL spectrum, and through studying the reaction of Ce(IV)-Na(2)SO(3)-Tb(III)-FLUQ with nucleotides and bases, we conclude that DNA counteracts the energy transfer from FLUQ to Tb(III), and this function is related to both bases and phosphate groups in DNA.     

Spectrophotometric studies and analytical application of Ce(III) chelates with 1-(2-pyridylazo)-2-naphthol (PAN)

A sensitive procedure for spectrophotometric determination of cerium(III) has been developed. AtpH 10.2 cerium reacts with 1-(2-pyridylazo)-2-naphthol in 40% ethanol to form a red complex which has an absorption maximum at 545 nm. The molar absorptivity at 545 is 3.95·10³ mol^–1. Maximum stability of the complex was attained in pure ethanol. The stoichiometries and structures of the chelates were studied applying conductometric titration, visible spectrophotometry and IR spectrophotometry. The IR spectra revealed that coordination takes place through the N=N, C-OH and pyridyl group.

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Spektrophotometrische Untersuchungen und analytische Anwendung von Ce(III)-Chelaten mit 1-(2-Pyridylazo)-2-naphthol (PAN)

Zusammenfassung Es wurde eine empfindliche Methode zur spektrophotometrischen Bestimmung von Cer(III) entwickelt. Bei einempH von 10,2 reagiert Cer mit 1-(2-Pyridylazo)-2-naphthol in 40% Ethanol unter Bildung eines roten Komplexes mit einem Absorptionsmaximum bei 545 nm (=3 950). Der Komplex besitzt in reinem Ethanol ein Maximum an Stabilität. Die Stöchiometrien und Strukturen der gebildeten 1:1- und 1:2-Chelate wurden mittels konduktometrischer Titration, Elektronen- und IR-Spektrometrie untersucht. Die IR-Daten zeigen, daß die Koordination über N=N, C-OH und Pyridyl erfolgt.

     

Effect of gold nanoparticle as a novel nanocatalyst on luminol-hydrazine chemiluminescence system and its analytical application

In this work the catalytic role of unsupported gold nanoparticles on the luminol–hydrazine reaction is investigated. Gold nanoparticles catalyze the reaction of hydrazine and dissolved oxygen to generate hydrogen peroxide and also catalyze the oxidation of luminol by the produced hydrogen peroxide. The result is an intense chemiluminescence (CL) due to the excited 3-aminophthalate anion. In the absence of gold nanoparticles no detectable CL was observed by the reaction of luminol and hydrazine unless an external oxidant is present in the system. The size effect of gold nanoparticles on the CL intensity was investigated. The most intensive CL signals were obtained with 15-nm gold nanoparticles. UV–vis spectra and transmission electron microscopy studies were used to investigate the CL mechanism. The luminol and hydroxide ion concentration, gold nanoparticles size and flow rate were optimized. The proposed method was successfully applied to the determination of hydrazine in boiler feed water samples. Between 0.1 and 30 μM of hydrazine could be determined with a detection limit of 30 nM.     

Simultaneous potentiometric determination of ClO(3)(-)-ClO(2)(-) and ClO(3)(-)-HClO by flow injection analysis using Fe(III)-Fe(II) potential buffer

A rapid potentiometric flow injection technique for the simultaneous determination of oxychlorine species such as ClO₃⁻–ClO₂⁻ and ClO₃⁻–HClO has been developed, using both a redox electrode detector and a Fe(III)–Fe(II) potential buffer solution containing chloride. The analytical method is based on the detection of a large transient potential change of the redox electrode due to chlorine generated via the reaction of the oxychlorine species with chloride in the potential buffer solution. The sensitivities to HClO and ClO₂⁻ obtained by the transient potential change were enhanced 700–800-fold over that using an equilibrium potential. The detection limit of the present method for HClO and ClO₂⁻ is as low as 5×10⁻⁸ M with use of a 5×10⁻⁴ M Fe(III)–1×10⁻³ M Fe(II) buffer containing 0.3 M KCl and 0.5 M H₂SO₄. On the other hand, sensitivity to ClO₃⁻ was low when a potential buffer solution containing 0.5 M H₂SO₄ was used, but could be increased largely by increasing the acidity of the potential buffer. The detection limit for ClO₃⁻ was 2×10⁻⁶ M with the use of a 5×10⁻⁴ M Fe(III)–1×10⁻³ M Fe(II) buffer containing 0.3 M KCl and 9 M H₂SO₄. By utilizing the difference in reactivity of oxychlorine species with chloride in the potential buffer, a simultaneous determination method for a mixed solution of ClO₃⁻–ClO₂⁻ or ClO₃⁻–HClO was designed to detect, in a timely manner, a transient potential change with the use of two streams of potential buffers which contain different concentrations of sulfuric acid. Analytical concentration ranges of oxychlorine species were 2×10⁻⁵–2×10⁻⁴ M for ClO₃⁻, and 1×10⁻⁶–1×10⁻⁵ M for HClO and ClO₂⁻. The reproducibility of the present method was in the range 1.5–2.3%. The reaction mechanism for the transient potential change used in the present method is also discussed, based on the results of batchwise experiments. The simultaneous determination method was applied to the determination of oxychlorine species in a tap water sample, and was found to provide an analytical result for HClO, which was in good agreement with that obtained by the o-tolidine method and to provide a good recovery for ClO₃⁻ added to the sample.     

Flow-injection chemiluminescence determination of quinine using on-line electrogenerated cobalt(III) as oxidant

A novel chemiluminescence (CL) flow system for the determination of quinine is described. It is based on the direct chemiluminescence reaction of quinine and cobalt(III) in sulfuric acid medium. The unstable Co(III) was on-line electrogenerated by constant-current electrolysis. The chemiluminescence intensity was linear with a quinine concentration in the range of 0.1-100 mug ml(-1). The determination limit was 3.3x10(-8) g ml(-1). The whole process could be completed in 1 min. The proposed method is suitable for automatic and continuous analysis, and has been applied successfully to the analysis of quinine in pharmaceutical preparation.     

Localized orbital calculations of the bonding in SO,SO2F2, ClO3F and SOCL2

Localized valence molecular orbitals have been obtained for SO, SO₂F₂, ClO₃F and SOCl₂ by the method due to Boys and Foster. The bonding in these molecules, in which the second row atom is exhibiting an excess valency, is discussed in terms of the form of these localized orbitals. The bonding of the second row atom to an oxygen atom is described by three bent bond orbitals, whilst bonding to a halogen atom is described by a single bond orbital. The participation of 3d functions in the various bonding and nonbonding orbitals is analysed in this localized orbital framework.     

Resonance Rayleigh scattering spectra of Cu2+-adenine-WO4(2-) system and its analytical application

In pH 6.6-7.2 Tris-HCl buffer, Cu(2+) could react with adenine (A) to form a 1:1 coordination cation [CuA](2+), which only resulted in minor change of the absorption spectrum. However, when this cation further combined with WO(4)(2-) to form a 1:1 ternary ion-association complex [CuA]WO(4), the absorption spectrum changed a lot, and the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) enhanced significantly. The maximum wavelengths of RRS, SOS and FDS were located at 310, 592 and 395 nm, respectively. The enhanced intensities of the three methods were proportional to the concentration of adenine in certain ranges, and the detection limit of the most sensitive RRS method was 7.4 × 10(-9) mol L(-1) (1.0 ng mL(-1)), indicating that this method could detect trace adenine. In this work, the optimum reaction conditions and the influencing factors have been studied, some potential interferences and the composition of the ion-association complex have been investigated. Meanwhile, the construction of the product and the reaction mechanism have been investigated by atomic force microscopy, transmission electron microscope and quantum chemical calculation. Accordingly, a novel RRS method for determination of adenine has been proposed and applied to detect adenine in real samples with satisfactory results.     

A direct hydrogen-1 and phosphorus-31 nuclear magnetic resonance cation solvation study of Al(ClO4)3, Ga(ClO4)3, In(ClO4)3, UO2(ClO4)2, and UO2(NO3)2 in water-acetone-dimethylsulfoxide and water-acetone-hexamethylphosphoramide mixtures

A competitive solvation study of Al(ClO₄)₃, Ga(ClO₄)₃, In(ClO₄)₃, UO₂(ClO₄)₂, and UO₂(NO₃)₂ in water-acetone-dimethylsulfoxide (DMSO) and water-acetone-hexamethylphosphoramide (HMPT) mixtures has been carried out by direct H¹ and P³¹ nuclear magnetic resonance (NMR) techniques. At low temperature, proton and ligand exchange are slow enough in these systems to permit the observation of signals for bulk and coordinated molecules of water and the organic bases (DMSO and HMPT). Both DMSO and HMPT compete effectively with water for coordination sites in the Al³⁺, Ga³⁺, and In³⁺ systems, with steric effects dominating the HMPT results. Both Al³⁺ and In³⁺ are able to bind a maximum of two to three HMPT molecules, for example. In contrast, UO²⁺ is solvated selectively by the organic molecules to the allowed maximum of 4 molecules per cation. H¹ and P³¹ NMR spectral results support the formation of only the mono-, tri-, and tetra-HMPT solvation complexes.     

Study on the chemiluminescence behavior of bovine serum albumin with luminol and its analytical application

In this paper, the luminescence behavior of bovine serum albumin (BSA) and luminol was first studied by flow injection chemiluminescence (CL). It was found that the hyperchromic effect of luminol in the presence of BSA led to the acceleration of the electrons transferring rate of excited 3-aminophthalate, which greatly enhanced the CL intensity of luminol/dissolved oxygen reaction. The increments of CL intensity were proportional to the concentrations of BSA with a linear range from 0.01 to 7 nmol L(-1). It was also found that azithromycin could inhibit the CL intensity of luminol/BSA reaction. The decrements of CL intensity were logarithm over the concentrations of azithromycin ranging from 0.1 to 700 ng mL(-1). At a flow rate of 2.0 mL min(-1), a complete analytical process, which included sampling and washing, could be performed within 30s with relative standard deviations of less than 3.1%. This proposed method was successfully applied in assaying azithromycin in pharmaceutical and human serum samples with recoveries from 91.0 to 104.3%. The possible luminescence mechanism of luminol/BSA/azithromycin reaction was discussed in detail by CL, UV and fluorescence methods.     

Colour reaction of gold with 5-(4-sodium sulphonatephenylazo)-8-aminoquinoline and its analytical application

The synthesis of 5-(4-sodium sulphonatephenylazo)-8-aminoquinoline (SPAQ) is described, and a simple, rapid, selective and sensitive new spectrophotometric method for determination of gold is developed. SPAQ reacts with gold(III), and in the presence of cetyl trimethyl ammonium bromide cationic surfactant and upon making the solution alkaline, forms a blue-green 1:3 (metal:ligand) with an absorption maximum at 605 nm. Beer's law is obeyed over the concentration range 0-2 microg/ml gold. The molar absorptivity and Sandell's sensitivity of the method are 1.48 x 10(5) 1.mole(-1).cm(-1) and 0.0013 microg/cm(2), respectively. The interference of various ions has been studied and the method has been used for the determination of microamounts of gold in ores and anode slimes.     

Selective light-triggered chemiluminescence between fluorescent dyes and luminol, and its analytical application

We report herein a novel chemiluminescence (CL) phenomenon triggered by light irradiation when a fluorescent dye, for example hematoporphyrin, fluorescein, eosin, or methylene blue is present in the luminol solution. A possible mechanism is proposed for the photoinduced chemiluminescence (PICL) reaction. Compared with reported methods for CL triggering, for example flow-injection, static reagent injection, and the electrochemical technique, the proposed in-situ PICL method presented has three advantages. First, the method is more selective, because the PICL signal of the target fluorescent dyes is initiated by excitation at a selective wavelength only. Second, the space and time resolution of the PICL method are better. Last, and most important, compared with injecting a reagent or inserting a electrode into the CL system to initiate the CL reaction, with the in-situ PICL method there is no physical interference with the target detecting system. All these advantages of the PICL method indicate it has many potential applications in the analytical sciences. The proposed method was applied to analysis of urine containing adrenaline. The linear range for adrenaline is 2.0?×?10^?10–1.0?×?10^?7 g mL^?1 and the detection limit is 6.0?×?10^?11 g mL^?1.