Flow injection electrogenerated chemiluminescence determination of vanadium and its application to environmental water sample

A selective flow injection electrogenerated chemiluminescence(CL) method for the determination of vanadium is described in this paper. It was based on the chemiluminescence reaction of luminol with vanadium(II), which was on-line electrogenerated from vanadate using a flow-through carbon electrolytic cell. Under the optimal conditions, the CL intensity was linear to the concentration of vanadium in the range of 5.0x10(-10)-1.0x10(-7) gml(-1) with a detection limit of 2x10(-10) gml(-1) vanadium. The relative standard deviation was 4% for 5.0x10(-8) gml(-1) vanadium in 11 repeated measurements. The method has been successfully applied to the determination of vanadium in environmental water samples.     

电致初生态氧化剂的化学发光行为研究及其分析应用

基于一种新型流通电解池的设计,结合恒电流电解技术与流动注射技术,使电生于电极表面附近的溴具有初生态的化学发光反应活性。它可直接氧化异烟肼而产生强度高、反应速度快的化学发光现象,据此建立了测定异烟肼的电化学发光新方法,同时,提出一种研究、探索初生态试剂化学发光分析的新思想和新方法。     

Flow-injection analysis of hydrogen peroxide based on carbon nanospheres catalyzed hydrogen carbonate-hydrogen peroxide chemiluminescent reaction

A flow-injection chemiluminescence (CL) system with high sensitivity, selectivity, rapidity, and reproducibility is proposed for the determination of hydrogen peroxide (H(2)O(2)) in water samples. The system is based on the reaction of hydrogen peroxide and hydrogen carbonate solution. Carbon nanospheres (CNSs) prepared from aqueous glucose solution are used to enhance the weak CL. The CL intensity was found to be directly proportional to the concentration of H(2)O(2) present in the sample solutions. The effects upon the CL of several physicochemical parameters, including the concentration of the reagents, the mixing order of the reagents, flow rate, pH, particle size of CNSs and other relevant variables, were studied and optimized. The proposed method exhibited advantages in a larger linear range of 5.0 × 10(-8) to 3.0 × 10(-6) mol L(-1) and a lower limit of detection of 1.0 × 10(-9) mol L(-1) (S/N = 3). This method has been successfully applied to the evaluation of H(2)O(2) in tap water and snow water with recoveries from 80 to 110%. The relative standard deviation (RSD) was less than 8% for intra- and inter-assay precision. Based on the kinetic curve, the CL spectrum, fluorescence spectrum, UV-visible spectrum, and electron spin resonance (ESR) spectrum of NaHCO(3)-H(2)O(2)-CNSs system, a possible CL mechanism was proposed. Superoxide ion radical (˙O(2)(-)) and hydroxide radical (˙OH) were generated during the reaction of NaHCO(3) and H(2)O(2). They were the key intermediates for the production of hole-injected and electron-injected CNSs in the CL process.     

在线电生强氧化剂钴(Ⅲ)化学发光法测定地塞米松磷酸钠

本文基于Co3+在硫酸介质中能氧化地塞米松磷酸钠产生化学发光这一特性,建立了一种流动注射化学发光测定地塞米松磷酸钠的新方法。其中不稳定的强氧化剂Co3+是通过在硫酸介质中恒电流电解CoSO4在线产生的,从而消除了由于试剂不稳定性带来的一些不利因素。该方法测定地塞米松磷酸钠的线性范围为1～20 mg/L,检出限为3.2×10－7g/mL(DL=3S/r),相对标准偏差小于5%。该方法已成功地用于地塞米松磷酸钠注射液中地塞米松磷酸钠的测定。     

Diffusion and Reactivity of Ruthenium (II) Tris(bipyridine) and Cobalt (II) Tris(bipyridine) in Organically Modified Silicates

The diffusivity and reactivity of Ru(bpy)²⁺ ₃ and Co(bpy)²⁺ ₃ trapped within organically modified silicate (ORMOSIL) monoliths have been studied using electrogenerated chemiluminescence, voltammetry, and amperometry. For gel-encapsulated Ru(bpy)²⁺ ₃-tripropylamine, the shape and intensity of the luminescence-voltage curve was highly dependent on the amount of organoalkoxysilane introduced into the matrix. Likewise, for gel-encapsulated Co(bpy)²⁺ ₃, the magnitude of the diffusion coefficient and its rate of change with drying was also dependent on the organic modifier in the gel. A comparison of the results to those obtained with the gels prepared solely from tetramethoxysilane revealed enhanced diffusivity and reactivity of the reagents encapsulated in the ORMOSIL matrix.     

Second chemiluminescence behavior of Fe2+, Fe3+ and Cr3+ in the luminal-KMnO4 system.

A novel flow injection chemiluminescence (CL) method has been developed for the determination of three metal ions, namely Fe2+, Fe3+ and Cr3+, based on the second CL (SCL) signal of the mixture of luminal with KMnO4 in a sodium hydroxide medium by the catalysis of Fe2+, Fe3+ or Cr3+. The possible CL mechanism of the systems, the influencing factors, and the optimum conditions for the reactions were investigated based upon the kinetic curve of the CL reaction, CL spectra, UV-visible spectra and some other experiments. Under the optimum conditions, the SCL intensity was directly proportional to the concentration of these metal ions in solution in the range of 0.10 - 100.00 mg l(-1) for Fe(2+), 0.50 - 7.50 and 7.50 - 200.00 mg l(-1) for Fe3+, 0.01 - 0.25 and 0.25 - 10.00 mg l(-1) for Cr3+. The detection limits (3 sigma/s) were 9.87 x 10(-6) g l(-1), 2.71 x 10(-6) g l(-1) and 5.25 x 10(-7) g l(-1) for Fe2+, Fe3+ and Cr3+, respectively.     

Flow Injection Chemiluminescence Determination of Isoniazid Using On-Line Electrogenerated Manganese(III) as Oxidant

A novel flow injection chemiluminescence (CL) system for the determination of isoniazid has been proposed. It is based on the direct CL reaction of isoniazid and Mn(III) in sulfuric acid medium. The unstable Mn(III) was on-line electrogenerated by constant current electrolysis. The CL emission intensity was linear with isoniazid concentration in the range 0.1–10 μg/mL; the detection limit was 3.2 × 10⁻² μg/mL. The whole process could be completed in 1 min with a relative standard deviation of less than 5%. The proposed method is suitable for automatic and continuous analysis and has been applied successfully to the analysis of isoniazid in pharmaceutical preparation.     

Lophine derivatives as versatile analytical tools

Lophine (2,4,5-triphenylimidazole) derivatives as versatile analytical tools in biomedical sciences are described. Chemiluminescence (CL) and fluorescence (FL) properties of the lophine derivatives are first demonstrated including the CL reaction mechanism, effects of substituents on CL yields, FL spectral behaviors, etc. Next, analytical applications to the determination of metal ions such as cobalt (II) and chromium (VI) are discussed. Finally, the application studies of lophine derivatives as CL and FL reagents for the determination of organic substances in biological materials are presented. Among the derivatives, 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) are studied, with their excellent properties as labeling reagents for fatty acids and amines and/or phenols, respectively, in high-performance liquid chromatography. The utility of boronic acid derivatives as CL enhancers is also discussed in this review.     

甲酸存在下 N-四氢苯并噻唑亚胺希夫碱的化学发光

新合成的N(2-四氢苯并噻唑)-2-羟基苯甲亚胺希夫碱与酸性高锰酸钾反应产生微弱的化学发光,甲酸的存在有显著的增敏作用。报道了其荧光光谱、化学发光光谱、紫外可见吸收光谱和化学发光动力学曲线,并建立了流动注射化学发光测定噻唑类希夫碱的方法。该法线性范围为1.0×10-7～8.0×10-5mol/L,检测限为5.0×10-8mol/L,对1.0×10-6mol/L噻唑类希夫碱11次平行测定的相对标准偏差为1.7％。     

Improved microfluidic chip-based sequential-injection trapped-droplet array liquid-liquid extraction system for determination of aluminium

An improved microfluidic chip-based sequential-injection trapped-droplet array liquid-liquid extraction system with chemiluminescence (CL) detection was developed in this work. Two recess arrays were fabricated on both sides of the extraction channel to produce droplet arrays of organic extractant. A chip integrated monolithic probe was fabricated at the inlet of the extraction channel on the glass chip instead of the capillary probe connected to the microchannel, in order to improve the system stability and reliability. A slotted-vial array system coupled with the monolithic probe was used to sequentially introduce sample and different solvents and reagents into the extraction channel for extraction and CL detection. The performance of the system was demonstrated in the determination of Al³⁺ using Al³⁺-dihydroxyazobenzene (DHAB) and tributyl phosphate (TBP) extraction system. The operation conditions, including extraction time, concentration and flow rate of the CL reagents, were optimized. Within one analysis cycle of 12 min, an enrichment factor of 85 was obtained in the extraction stage with a sample consumption of 1.8 μL. The consumption of CL reagent, bis(2-carbopentyloxy-3,5,6-trichlorophenyl)oxalate (CPPO), was 120 nL/cycle. The detection limit of the system for Al³⁺ was 1.6 × 10⁻⁶ mol/L with a precision of 4.5% (R.S.D., n = 6).     

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.     

Characterization of cardiolipin as the sodiated ions by positive-ion electrospray ionization with multiple stage quadrupole ion-trap mass spectrometry

The application of multiple-stage ion-trap (IT) mass spectrometric methods for the structural characterization of cardiolipin (CL), a 1,3-bisphosphatidyl-sn-glycerol that consists of four fatty acyl chains and three glycerol backbones (designated as A, B, and central glycerol, respectively), as the sodiated adduct ions in the positive-ion mode was evaluated. Following collisionally activated dissociation (CAD), the [M - 2H + 3Na]+ ions of CL yield two prominent fragment ion pairs that consist of the phosphatidyl moieties attached to the 1'- and 3'-position of the central glycerol, respectively, resulting from the differential losses of the diacylglycerol moieties containing A and B glycerol, respectively. The results are consistent with those previously described for the [M - H]- and [M - 2H + Na]- ions in the negative-ion mode, thus permitting assignment of the two phosphatidyl moieties attached to the 1'- or 3'-position of the central glycerol. The identities of the fatty acyl substituents and their positions on the glycerol backbones (glycerol A and B) are deduced from further degradation of the above ion pairs that give the fragment ions reflecting the fatty acid substituents at the sn-1 (or sn-1') and sn-2 (or sn-2') positions. The ions that arise from losses of the fatty acid substituents at sn-1 and sn-1', respectively, are prominent, but the analogous ions from losses of the fatty acid substituents at sn-2 and sn-2', respectively, are of low abundance in the MS2 product-ion spectra. This feature further confirms the assignment of the positions of the fatty acid substituents. The similar IT multiple-stage mass spectrometric approaches including MS2 and MS3 for structural characterization of CL using its [M + Na]+ and the [M - H + 2Na]+ ions are also readily applicable. However, their uses for structural characterization are less desirable because formation of the [M + Na]+ and the [M - H + 2Na]+ ions for CL is not predictable.     

利用Cr_2O_3-LaCoO_3-Pt纳米材料催化发光测定大气中的氨分子

研究了氨分子在Cr_2O_3纳米粒子（粒径50 ～ 80 nm）表面的化学发光行为， 发现这种纳米材料对氨分子具有较强的选择性。进一步的研究表明，在掺杂了 LaCoO_3纳米粒子（粒径20 nm）和Pt纳米粒子（粒径≤10 nm）后，化学发光强度 增强了近25倍。在最佳反应条件下，化学发光强度与氨分子的浓度在15.0 * 10~(- 6) ～ 750 * 10~(-6)内呈良好的线性关系（r = 0.995），检出限为4.0 * 10~(- 6)。     

Patterning of polystyrene by scanning electrochemical microscopy. Biological applications to cell adhesion

Polystyrene surfaces may be patterned by Ag(II), NO(3)(?), and OH(?) electrogenerated at the tip of a scanning electrochemical microscope. These electrogenerated reagents lead to local surface oxidation of the polymer. The most efficient surface treatment is obtained with Ag(II). The patterns are evidenced by XPS and IR and also by the surface wettability contrast between the hydrophobic virgin surface and the hydrophilic pattern. Such Ag(II) treatment of a polystyrene Petri dish generates discriminative surfaces able to promote or disfavor the adhesion of proteins and also the adhesion and growth of adherent cells. The process is also successfully applied to a cyclo-olefin copolymer and should be suitable to pattern any hydrogenated polymer.     

Study on Electrochemiluminesce of Ru(bpy3)2+ Immobilized in a Titania Sol‐Gel Membrane

The immobilization of tris(2,2′‐bipyridyl)ruthenium(II), Ru(bpy)₃²⁺, at a glassy carbon electrode was achieved by entrapping the Ru(bpy)₃²⁺ in a vapor deposited titania sol‐gel membrane. The electrogenerated chemiluminescence (ECL) of the immobilized Ru(bpy)₃²⁺ was studied. The Ru(bpy)₃²⁺ modified electrode showed a fast ECL response to both oxalate and proline. The ECL intensity was linearly related to concentrations of oxalate and proline over the ranges from 20 to 700 μmol L^?1 and 20 to 600 μmol L^?1, respectively. The detection limits for oxalate and proline at 3σ were 5.0 μmol L^?1 and 4.0 μmol L^?1, respectively. This electrode possessed good precision and stability for oxalate and proline determinations. The electrogenerated chemiluminescence mechanism of proline system was discussed. This work provided a new way for the immobilization of Ru(bpy)₃²⁺ and the application of titania sol‐gel membrane in electrogenerated chemiluminescence.     

Chemiluminescence flow sensor for folic acid with immobilized reagents.

A novel chemiluminescence (CL) sensor for folic acid combined flow-injection (FI) technology was presented in this paper. The analytical reagents involved in the CL reaction, including luminol and hexacyanoferrate(III), were both immobilized on an anion-exchange column in FI system. The CL signal produced by the reaction between luminol and hexacyanoferrate(III), which were eluted from the column through sodium phosphate injection, was decreased in the presence of folic acid. The CL emission was correlated with the folic acid concentration in the range from 0.01 to 15 microg ml(-1), and the detection limit was 3.5 ng ml(-1) folic acid (3sigma). At a flow rate of 2.0 ml min(-1), including sampling and washing, could be performed in 2 min with a relative standard deviation of < 2.5%. The flow sensor could be reused more than 300 times and has been applied to the analysis of folic acid in pharmaceutical preparations. and the recovery was from 97.4% to 100.4%.     

A green approach for the electroorganic synthesis of 2-[(4-methyl-2-pyridyl)amino]-1,4-benzenediol derivatives in aqueous solution

The electrochemical synthesis of some new 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives was performed via the electrochemical oxidation of hydroquinones in the presence of 2-amino-4-methylpyridine in an aqueous solution. The results demonstrate that electrogenerated p-benzoquinone participated in the Michael-type addition reaction via an electrochemical–chemical (EC) reaction mechanism pathway and converted to the corresponding 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives. These new compounds have been synthesized in high yields and purity without using any toxic reagents or catalyst at the surface of carbon electrode.     

High throughput method for the analysis of cetrizine hydrochloride in pharmaceutical formulations and in biological fluids using a tris(2,2'-bipyridyl)ruthenium(II)-peroxydisulphate chemiluminescence system in a two-chip device

A fast, economic and sensitive chemiluminescence (CL) method has been developed for the analysis of cetrizine hydrochloride (CET) in pharmaceutical formulations and in biological fluids. The CL method is based on the oxidation of tris(2,2′-bipyridyl)ruthenium(II) (Ru (bipy)₃²⁺) by peroxydisulphate in a two-chip device. Up to 180 samples can be analysed per hour, consuming only minute quantities of reagents. Three instrumental setups were tested to find the most economical, sensitive and high throughput setup. In the first setup, a continuous flow of sample and CL reagents was used, whereas in the second setup, a fixed volume (2 μL) of (Ru (bipy)₃²⁺) was introduced into a continuous infusion of peroxydisulphate and the sample. In the third design, a fixed volume of sample (2 μL) was injected while the CL reagents were continuously infused. Compared to the first setup, a 200% signal enhancement was observed in the third setup. Various parameters that influence the CL signal intensity, including pH, flow rates and reagent concentrations, were optimized. A linear response was observed over the range of 50 μg L⁻¹ to 6400 μg L⁻¹ (R² = 0.9959) with RSD values of 1.1% (n = 15) for 1000 μg L⁻¹. The detection limit was found to be 15 μg L⁻¹ (S/N = 3). The amount of consumed sample was only 2 μL, from which the detected amount of CET was found to be 6.5 × 10⁻¹⁴ mol. This procedure was successfully applied to the analysis of CET in pharmaceutical formulations and biological fluids.     

Equilibria occurring between beryllium (II) and salicylate ions

The complexation equilibria between Be2+ and the hydrogen salicylate (HL-) ions have been studied, at 25 degrees C, by potentiometric measurements with a glass electrode in 3 M NaClO4. The concentrations of metal (CM) and ligand (CL) were varied between 10(-3) and 0.03 M and 2 x 10(-3) and 0.03 M, respectively, while 1 < or = CL/CM < or = 3. The hydrogen ion concentration ranged from 10(-3) to 10(-5.3) M when basic salts start to precipitate. The equilibria can be written in the general form as: pBe2+ + rHL- <==> Be(p)H(-q) (HL)r(2p-r-q) + qH+, log beta(pqr). The experimental data have been explained with the formation of BeHL+ (log beta101 = 1.46 +/- 0.05), BeL (log beta111 = -0.897 +/- 0.018), BeL2(2-) (log beta122 = -3.746 +/- 0.021), Be2(OH)L2- (log beta232 = -5.23 +/- 0.09), Be3(OH)3L3(3-) (log beta363 = -14.39 +/- 0.12). The uncertainties represent 3sigma. The predominant complex in the whole concentration range studied is the uncharged mononuclear species BeL.     

Tris (2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence in analytical science

Ru(bpy) ₃ ²⁺ electrogenerated chemiluminescence (CL) has rapidly gained importance as a sensitive and selective detection method in analytical science. The Ru(bpy) ₃ ²⁺ ECL is observed when Ru(bpy) ₃ ³⁺ reacts with Ru(bpy) ₃ ⁺ and yields an excited state Ru(bpy) ₃ ^2+* . ECL emission can also be obtained when a variety of oxidants and reductants react with the reduced or oxidized forms of Ru(bpy) ₃ ²⁺ . Either the reductant or the oxidant can be treated as an analyte. The Ru(bpy) ₃ ²⁺ ECL is used as a detection method for the determination of oxalate and a variety of amine-containing analytes without derivatization in flowing streams such as flow injection and HPLC. When the ECL format is used as a detector for HPLC, unstable post-column reagent addition can often be eliminated and, the problems of both sample dilution and band broadening can be avoided because the Ru(bpy) ₃ ³⁺ species are generatedin situ in the reaction/observation flow cell. Since NADH is sensitively detected with the Ru(bpy) ₃ ²⁺ ECL, many clinically important analytes can be detected by coupling them to dehydrogenase enzymes that utilize -nicotinamide adenine cofactors to convert NAD⁺ to NADH. Ru(bpy) ₃ ²⁺ -derivatives are used as CL labels for immunoassay and PCR assay with Ru(bpy) ₃ ²⁺ /tripropylamine ECL system. The Ru(bpy) ₃ ²⁺ ECL label can be sensitively determined at subpicomolar concentrations, along with an extremely wide dynamic range of greater than six orders of magnitude. Furthermore, it can eliminate disposal and lifetime problems inherent in radio immunoassays. In this paper, basic principles of the Ru(bpy) ₃ ²⁺ ECL are discussed. In addition, analytical applications of the Ru(bpy) ₃ ²⁺ ECL are illustrated with examples.