An ECL biosensor for glucose based on carbon-nanotube/Nafion film modified glass carbon electrode

Glucose oxidase was encapsulated in carbon-nanotube/Nafion film modified glass carbon electrode and was used as electrochemiluminescence (ECL) biosensor for glucose. The glucose oxidase can be fixed firmly in the Nafion film and carbon nanotubes offer excellent electrocatalytic activity toward luminol and hydrogen peroxide liberated in enzymatic reaction between glucose oxidase and glucose, which would enable sensitive determination of glucose. Under the optimum condition, the linear response range of glucose was found to be 5.0 × 10⁻⁶ to 8.0 × 10⁻⁴ mol/L, and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) was 2.0 × 10⁻⁶ mol/L. The present carbon-nanotube/Nafion biocomposite glucose oxidase ECL biosensor showed excellent properties for sensitive determination for glucose with good reproducibility and stability, and it has been used to determine the glucose concentrations in real serum samples with the satisfactory results.     

Neodymium (III) hexacyanoferrate (II) nanoparticles induced by enzymatic reaction and their use in biosensing of glucose

The formation of neodymium (III) hexacyanoferrate (II) (NdHCF) nanoparticles (NPs) on the surface of carbon-paste electrode induced by enzymatic reaction was described and characterized. The conditions for biosensing of glucose were optimized through various experiments. Results showed that the optimized condition of the glucose oxidase (GOx)-induced NdHCF NPs for the biosensing of glucose were 2.0 mM Nd³⁺, 40.0 mM Fe(CN)₆³⁻ and 20 μg/mL GOx. The biocatalyzed generation of NdHCF NPs in the presence of O₂/glucose and GOx enabled the development of an electrochemical biosensor for glucose. Furthermore, this system avoids the interferences from other species for the biosensing of glucose.     

鲁米诺-过氧化氢体系对敌敌畏的检测分析

通过化学发光（CL）技术，基于碱性鲁米诺－H2O2体系与敌敌畏的反应，直接对敌敌畏进行检测，并对反应条件进行优化。为有机磷农药的检测提供方便、可靠的分析方法。     

Self-assembly electrode based on silver nanoparticle toward electrogenerated chemiluminescence analysis of glucose

Electrogenerated Chemiluminescence (ECL) involves applying a certain electric potential to a chemical reaction, resulting in the oxidation or reduction of the substance which reacts to produce light. We determined the amount of glucose by its reaction to glucose oxidase (GO _X ) on the surface of the proposed modified electrode, which results hydrogen peroxide (H₂O₂) as side product. After that the reactions between luminol and H₂O₂ under oxidizing conditions generate dependent light which can be used to analyze. In the current article at first we proposed a convenient method to obtaining a self-assembly modified electrode. A nano based modified glassy carbon (GC) electrode (Glucose oxidase/Ag nanoparticles/cysteamine (CA)/p-aminobenzene sulfonic acid/GC electrode) was prepared, and the ECL behavior of luminol in the presence of glucose was examined. Compared to the bare GC electrode, the modified electrode incorporating glucose oxidase significantly enhanced the response of the ECL biosensor to glucose due to the enhanced specificity of the modified surface to enzymatic reaction, and the sensitivity of the luminol ECL reaction. Under optimal conditions, the electrode was established to respond linearly to glucose in the concentration range 5.0×10^?7 to 8.0×10^?3 mol/L, and the detection limit was established to be a glucose concentration of 4.0×10^?8 mol/L.     

鲁米诺化学发光体系应用新进展

综述了近几年来鲁米诺化学发光法在无机、有机和免疫分析中应用的最新进展。     

KMnO_4-L-cys包覆ZnCdSe量子点化学发光对头孢羟氨苄的测定

试验发现KMnO4可氧化L-cys包覆ZnCdSe量子点产生强烈的化学发光现象,而头孢羟氨苄对该体系的化学发光具有很强的抑制作用,基于此,首次建立了头孢羟氨苄的流动注射化学发光抑制分析法。结果表明,发光信号的降低值ΔΙ与头孢羟氨苄的浓度在2.1×10-9~1.6×10-5g/mL的范围内呈良好的线性关系,检出限为1.7×10-9g/mL。对1×10-5g/mL头孢羟氨苄测定的相对标准偏差为1.89%(n=11),加标回收率在95%~103%之间。本方法快捷、简便且具有很高的灵敏度,可用于头孢羟氨苄的测定,结果满意。     

Interaction between gold (III) chloride and potassium hexacyanoferrate (II/III)—Does it lead to gold analogue of Prussian blue?

Prussian blue analogues are a class of compounds formed by the reaction between metal salt and potassium hexacyanoferrate (II/III). In our earlier report, the formation of Au@Prussian blue nano-composite was noticed on potential cycling the glassy carbon electrode in a medium containing gold (III) chloride and potassium hexacyanoferrate (III). Hence in this work, the formation of gold hexacyanoferrate was attempted by a simple chemical reaction. The reaction of gold (III) chloride with potassium hexacyanoferrate (II/III) was examined by UV–Vis spectroscopy and found that there is no redox reaction between gold (III) chloride and potassium hexacyanoferrate (III). However, the redox reaction occurs between gold (III) chloride and potassium hexacyanoferrate (II) leading to the formation of charge transfer band and the conversion of hexacyanoferrate (II) to hexacyanoferrate (III) was evidenced by the emergence of new absorption peaks in UV–Vis spectra. The oxidation state of gold in Au–Fe complex was found to be +1 from X-ray photoelectron spectroscopy. The stability of the Au–Fe complex was also studied by cyclic voltammetry. Cyclic voltammetric results indicated the presence of high spin iron in Au–Fe complex. Hence ‘as formed’ Au complex may be KFe_x[Au(CN)₂]_y. The results revealed that the formation of gold hexacyanoferrate was not feasible by simple chemical or electrochemical reaction in contrast to other Prussian blue analogues.     

环境雌激素双酚A的化学发光法测定

在碱性条件下,鲁米诺和过硫酸钾能产生稳定的发光信号,而双酚A的存在能够明显抑制发光信号的强度。由此建立测定微量双酚A的流动注射化学发光分析方法。双酚A的浓度在9．0×10^-9～1．0×10^-5mol／L范围与相对化学发光强度（△I）呈线性关系,线性方程为△I=471．363×CBPA＋62．607,相关系数为0．9992,检出限为9．9×10^-10mol／L。该法用于实际水样的双酚A的测定,RSD为0．72%（n=11）。加标实验回收率为100．8％-103．0％。     

Etude de l'oxydation du pentachlorophénol dans différentes géométries de réacteurs à ultrasons de haute fréquence

The determination of the key geometric parameters used for high-frequency sonoreactor modeling has been studied. The methodology allowing the characterization of the different reactors built in our laboratory has been defined. The methods are: calorimetry, determination of the residence time distributions, the observation of the chemiluminescence of luminol and the degradations of a prototype molecule: pentachlorophenol. After characterization of the studied reactors, it seems that volumetric power, with equivalent emitting system, is the major parameter of the reactor's performance.     

A highly performing electrochemiluminescent biosensor for glucose based on a polyelectrolyte-chitosan modified electrode

A highly performing ECL glucose biosensor was developed by immobilizing glucose oxidase (GOD) onto a membrane modified glassy carbon electrode, which was prepared by using poly(diallyldimethylammonium chloride) (PDDA) doped with chitosan. In order to obtain the optimal performance of the ECL biosensor, the composition of modified membranes and a series of measurement conditions were investigated. Under the optimal conditions, this ECL biosensor was able to detect glucose in the range of 0.5-4.0 × 10⁴ nM with a detection limit of 0.1 nM (defined as the concentration that could be detected at the signal-to-noise ratio of 3). The relative standard deviation was 0.99% for 5 × 10⁻⁸ mol/L glucose in repetitive measurements in the primary 12 potential cycles. This ECL biosensor offered the effectively improved stability of the electron transfer mediator and exhibited excellent properties for the ultrasensitive and selective determination of glucose with good reproducibility and stability. The present biosensor has also been used to determine the glucose concentrations in real serum samples. The recovery value for the assay of glucose ranged from 96.2 to 107% in the serum samples. The present biosensor displayed both specificity for glucose and retention of signal response even in a complex environment. Therefore, it provided an approach to the sensitive determination of glucose.     

A fully automated flow injection atomic absorption system for the determination of copper traces in waters with on-line pre-concentration in an ion-exchange column

The paper describes the development of an automatic on-line column pre-concentration technique using a time based-flow injection atomic absorption spectrometry system. A manifold incorporating a micro-column containing 25 mg of Dowex 50W-X8 was used with a time-based injector for the pre-concentration and determination of copper in natural and drinking waters. The system features depend on the alternate positions of a solenoid valve. The 3σ detection limits, enrichment factors, sampling frequency, relative standard deviations and linear calibration graphs were, respectively, in the range 0.6-1.5 μg/l, 25-60, 15-30 measurements/h, 1.0-3.1% and 1-65 μg/ml for pre-concentration times of 1 min. The procedure was successfully applied to a range of water samples and the accuracy was assessed through recovery experiments, the analysis of certified reference water samples and by independent analysis by atomic absorption spectrometry with electrothermal atomization.     

Mixed valences system in cobalt iron cyanide. Microporous structure stability

Divalent transition metal hexacyanoferrates(III) have a microporous framework appropriate for separation and storage of small molecules. The nature of such porous framework is found in the existence of systematic vacancies of the building unit, the hexacyanoferrate octahedral block, [Fe(CN)₆], in the material structure. The relatively low thermal stability appears to be the main limitation of these materials for such applications. In the as-synthesized material the available free volume is occupied by water which, can be removed by moderated heating but always involving decomposition of at least a small sample fraction. For cobalt a unique behavior has been observed. The heating of cobalt(2+) hexacyanoferrate(III) leads to an inner charge transfer to form the mixed valences Co(2+)Co(III) hexacyanoferrate(II,III) system. Since this inner oxidation–reduction reaction does not modify the coordination environments for the involved metals, the porous nature of the parent compound could be preserved and at the same time with a higher thermal stability related to the formation of the most stable ferrous species. The porous structure of the obtained material was evaluated from CO₂ adsorption, X-ray diffraction, thermo-gravimetric, and infrared and Mössbauer spectroscopic data. The heat-induced charge transfer is accompanied of a progressive fracture of the material crystallites and also of a decrease for the pore volume as detected by the CO₂ adsorption. For comparative purposes, a parallel study on a porous Prussian blue (ferric hexacyanoferrate(II)) species was carried out. The porous framework of this last material is also related to systematic vacancies of the hexacyanoferrate building block but without the mentioned heat-induced charge transfer effect. In this case the sample heating has no effect on the material porous properties.     

血催化鲁米诺化学发光性能的研究

采用荧光分光光度法,建立了血催化过氧化氢氧化鲁米诺的化学发光体系。考察了缓冲体系、pH值、血液浓度等对鲁米诺化学发光性能的影响。结果表明,当采用56.60mmol·L^-1 Na2CO3-NaHCO3缓冲体系与30.0mmol·L^-1 H2O2溶液（B液）混合时,在pH=8.98的条件下,血液浓度越高,血催化鲁米诺化学发光性能越好。     

Automatic continuous on-line monitoring of salicylic acid and acetylsalicylic acid in pharmaceuticals

An asymmetrical FIA merging-zones manifold based on the dual injection of two sample microvolumes was developed for the simultaneous determination of salicylic acid and acetylsalicylic acid in pharmaceutical preparations at a sampling frequency of 30/h. The complex formed between the Fe(III) reagent continuously introduced in the system and salicylic acid was monitored photometrically at 520 nm. One of the sample plugs was prehydrolysed on injection into an NaOH stream and was circulated through a longer channel than the other plug. This yielded two FIA peaks corresponding to salicylic acid and the overall content, respectively. The proposed manifold was successfully used to control the dissolution test of a pharmaceutical preparation.     

低压离子色谱柱后偶合化学发光测定蔬菜中碘离子

以NaNO3作洗脱液,碘离子经低压离子色谱柱分离与KIO4反应后,再与鲁米诺发生化学发光。经试验测定碘离子浓度在8.0×10-5~5.0×10-8g/mL范围内与发光强度呈良好的线性关系;检出限为8.0×10-9g/mL(3σ);相对标准偏差为0.8%。     

A Polyhedral Oligomeric Silsesquioxane (POSS) Doped with Cerium(III) / Fe(II) and its Application as an Electrochemical Sensor for L-dopamine

Silicon - A Polyhedral oligomeric silsesquioxane (POSS) doped with cerium (III) was synthesized and reacted with potassium hexacyanoferrate (SCeH). The vibrational, structural, morphological and...     

Determination of residual solvent in oilseed meals and flours: III. Isopropanol

A relatively simple volatilization procedure is described for the determination of residual isopropanol in oilseed meals and flours. A 1 g sample is placed in a 100 ml serum bottle, 200 μl of distilled water containing 0.075 mg of ethanol is added and the bottle is sealed with a rubber stopper and heated at 110 C for 1 hr. A 2 ml aliquot of the headspace gas is analyzed by gas chromatography using the added ethanol as an internal standard. Values determined by this procedure for three cottonseed, two peanut and two fish meals or flours which had been processed with isopropanol, ranged from 10 to 12,000 ppm and were of the same order of magnitude as values determined by a modification of the Todd azeotropic distillation procedure. Advantages of the volatilization over the azeotropic distillation procedure are that less operator and gas chromatograph time are required per analysis. Presented at the AOCS Meeting, New Orleans, April 1970. So. Utiliz. Res. Dev. Div., ARS, USDA. An erratum to this article is available at .     

Integrated luminometer for the determination of trace metals in seawater using fluorescence, phosphorescence and chemiluminescence detection

The paper describes an integrated luminometer able to perform fluorescence (FL), room temperature phosphorescence (RTP) and chemiluminescence (CL) measurements on seawater samples. The technical details of the instrumentation are presented together with flow injection (FI) manifolds for the determination of cadmium and zinc (by FL), lead (RTP) and cobalt (CL). The analytical figures of merit are given for each manifold and results are presented for the determination of the four trace metals in seawater reference materials (NASS-5, SLEW-2) and Scheldt estuarine water samples.     

An electrocatalyst for detection of glucose in human blood: synergy in Pd–AuNPs/GOx/C surfaces

Glucose oxidase (GOx)-based amperometric enzyme electrodes have been the target of substantial research. In this study, new amperometric biosensor for determination of glucose was developed. GOx enzyme was immobilized at bovine serum albumin via entrapment method. For this reason, the optimum conditions of Pd–Au NPs/GOx/C-modified glassy carbon electrode were determined. The electron is directly transferred from glucose to the electrode via the active site of the enzyme. The absence of mediators is the main advantage of such third-generation biosensors. The resulting materials were characterized employing scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. In addition, the effects of glucose concentration, scan rate, temperature, electroactive interference, stability, reusability of the biosensors were discussed. The applicability to blood analysis was also evaluated. The biosensor has a limit of detection for the determination of glucose 0.0014?mM.     

Adaptation of a cold vapour mercury analyser to flow injection analysis

Minor modifications to a Coleman MAS-50A Mercury Analyser System allowed the determination of mercury by flow injection analysis. Using sample volumes of 600 μl it was possible to analyse up to 120 samples per hour, with a detection limit of 0.2 μg. l^-1 (120 pg) of mercury. The authors also report on a simple digestion procedure which replaces the time- and reagent-consuming EPA procedure, when the sample content permits.