title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Simplex optimization of ion-pair reversed-phase high performance liquid chromatographic analysis of some heavy metals. | The sequential simplex algorithm was used to optimize the ion-pair reversed phase high performance liquid chromatographic (IP-RPHPLC) analysis of 4-(2-pyridylazo)resorcinol (PAR) chelates of Co(II), Ni(II) and Cr(III). A chromatographic response function (CRF) which included the number of peaks, the resolution between ... | 18,968,540 |
Determination of trace amounts of germanium by flow injection hydride generation atomic fluorescence spectrometry with on-line coprecipitation. | A method for the determination of trace amounts of germanium by hydride generation atomic fluorescence spectrometry (HG-AFS) associated on-line with flow injection (FI) coprecipitation preconcentration was described. The samples, each spiked with Ni(2+) (500 mugml(-1)), were introduced into the FI system using time-bas... | 18,968,547 |
Electrochemical sensor for detection of unmodified nucleic acids. | We have developed a nucleic acid (NA) sensor based on mediated electrochemical oxidation of guanine residues. In this method, oligonucleotide probes are bound to a tin-doped indium oxide (ITO) electrode through a self-assembled phosphonate monolayer. The end carboxyl moiety of the monolayer is activated with carbodiimi... | 18,968,560 |
Interaction of DNA with echinomycin at the mercury electrode surface as detected by impedance and chronopotentiometric measurements. | The capacitance measurement (dependence of the differential capacitance C of the electrode double layer on potential E, C-E curves), electrochemical impedance spectroscopy (frequency response of the impedance Z of the electrode double layer-EIS) and constant current chronopotentiometry (dependence of dt/dE on potential... | 18,968,569 |
Superheated water eluent capillary liquid chromatography. | A capillary scale reverse phase liquid chromatography (LC) system using a super hot water eluent is described. The system, constructed in-house from readily available components, has been shown to operate at temperatures as high as 370 degrees C and pressures in excess of 10 000 psi. The capability of the system is dem... | 18,968,577 |
Aromatic compounds in molecular phase of Baltic amber-synchronous luminescence analysis. | Synchronous luminescence analysis was performed in order to identify aromatic compounds in solvent extracts of Baltic amber. The investigated extracts were obtained, for comparisons, as products of extraction by various techniques and solvents. Methylene chloride and ethanol were applied independently for extraction at... | 18,968,585 |
Determination of urinary lead, cadmium and nickel in steel production workers. | The determination of toxic metals in urine is an important clinical screening procedure. In this study, the aim of our investigation was to determine the concentrations of Pb, Cd, and Ni in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as d... | 18,968,591 |
Synthesis of polyacrylaminoimidazole chelating fiber and properties of concentration and separation of trace Au, Hg and Pd from samples. | A novel polyacrylaminoimidazole chelating fiber is synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber) and used for the preconcentration and separation of trace Au(III), Hg(II) and Pd(IV) ions from solution samples. The analyzed ions can be quantitatively concentrated by the fiber up t... | 18,968,608 |
Continuous flow analysis of iron in zinc electrowinning electrolyte using an iron chalcogenide glass ion-selective electrode Part I. Synthetic media. | It is shown that the iron(III) chalcogenide glass membrane ion-selective electrode (ISE) can be calibrated in continuous flow analysis (CFA) using acidified iron(III) nitrate standards, yielding a 60+/-3 mV per decade change in activity of Fe(3+) response in the range 10(-7)-10(-2) M total iron(III). Extended ageing of... | 18,968,611 |
Use of constrained DET probe for a high-resolution determination of metals and anions distribution in the sediment pore water. | The constrained DET (diffusive equilibrium in thin films) probe filled with agarose gel was successfully used for measuring depth profiles of metals and anions in estuarine sediments at high-resolution (mm). The agarose gel was tested for equilibration times and recoveries. For manganese (10 mg l(-1)), the equilibratio... | 18,968,614 |
A highly stable biosensor for phenols prepared by immobilizing polyphenol oxidase into polyaniline-polyacrylonitrile composite matrix. | A novel biosensor for phenols was constructed by immobilizing polyphenol oxidase (PPO) into polyaniline-polyacrylonitrile composite matrix. The sensing film was prepared by electropolymerization of aniline into polyacrylonitrile (PAN)-coated platinum electrode in the presence of PPO. The scanning electron micrographs (... | 18,968,629 |
The application of the chromatomembrane cell for the absorptive sampling of nitrogen dioxide followed by continuous determination of nitrite using a micro-flow injection system. | A simple and rapid procedure for NO(2) determination in air was developed by coupling the chromatomembrane method with a micro-FIA system. A three-hole chromatomembrane cell was successfully applied to on-line preconcentration of atmospheric NO(2) in a solution of 2 g l(-1) triethanolamine (TEA) as an aqueous absorbing... | 18,968,636 |
Amperometric sensor for glucose and hypoxanthine based on a PdIrO(2) modified electrode by a co-crosslinking bienzymic system. | A glassy carbon electrode (GCE) modified with Pd/IrO(2) provides excellent electrocatalytic oxidation of hydrogen peroxide. Glucose oxidase (GOD) and xanthine oxidase (XOD) were co-immobilized on the modified electrode with a thin film Nafion coated on the enzyme layer to form a glucose (Glu)/hypoxanthine (Hx) sensor, ... | 18,968,637 |
Combined cation-exchange and extraction chromatography for the concomitant separation of Zr, Hf, Th, and the Lanthanides from geological materials. | A new method was developed, aiming to overcome the iron and titanium interferences which severely limit the applications of a recently introduced extraction chromatography material, referred to as RE resin (formerly, RE Spec), to the analysis of geological samples. The separation scheme is based on the combined use, in... | 18,968,640 |
Voltammetric behaviour and trace determination of copper at a mercury-free screen-printed carbon electrode. | Screen-printed carbon electrodes (SPCEs), without chemical modification, have been investigated as disposable sensors for the measurement of trace levels of Cu(2+). Cyclic voltammetry was employed to elucidate the electrochemical behaviour of Cu(2+) at these electrodes in a variety of supporting electrolytes. For all o... | 18,968,656 |
Sample pre-treatment methods for the trace elements determination in seafood products by atomic absorption spectrometry. | Different sample pre-treatments for seafood products have been compared with determine trace elements (As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Se and Zn) by flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). Classic pre-treatments as microwave assisted-acid digestion and ... | 18,968,702 |
Carbon-13 NMR spectroscopic studies on chemically modified and unmodified synthetic and natural humic acids. | Carbon-13 cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy ((13)C-CP/MAS-NMR) was applied to study the chemical modification process of humic acids (HA) with diazomethane and the subsequent alkaline hydrolysis of the methylated HA. This modification process results in HA with selectively ... | 18,968,705 |
Design of a composite amperometric enzyme electrode for the control of the benzoic acid content in food. | A graphite-Teflon-tyrosinase composite biosensor for the determination of benzoic acid in foodstuffs is reported. The biosensor functioning is based on the inhibition effect of benzoic acid on the biocatalytic activity of the enzyme in a reversed micelle working medium formed with ethyl acetate as the continuous phase,... | 18,968,725 |
Electrochemical measurement and speciation of inorganic arsenic in groundwater of Bangladesh. | The presence of arsenic in groundwater above the maximum permissible limit of 50 mug l(-1) has threatened the health of more than 50 million people in Bangladesh and neighboring India. We report here the development of an inexpensive anodic stripping voltammetric (ASV) technique for routine measurement and speciation o... | 18,968,732 |
Determination of arsenite, arsenate, and monomethylarsonic acid in seawater by ion-exclusion chromatography combined with inductively coupled plasma mass spectrometry using reaction cell and hydride generation techniques. | This paper describes a robust and sensitive method for the determination of arsenic species in seawater by ion-exclusion liquid chromatography (LC) combined with inductively coupled plasma mass spectrometry (ICP-MS) using reaction cell and hydride generation (HG) techniques. A good separation of arsenite, arsenate, and... | 18,968,739 |
Application of FT-IR spectroscopy to the characterisation and classification of wines, brandies and other distilled drinks. | FT-IR spectra were employed for the differentiation and classification of wines and brandies during their ageing process, as well as for the characterisation and differentiation of distilled drinks from several producing countries. The FT-IR spectra have enabled the differentiation of the six scales of ageing of sherry... | 18,968,750 |
Cyclodextrin enhanced spectrofluorimetric determination of fluoxetine in pharmaceuticals and biological fluids. | The characteristics of host-guest complexation between methyl-beta-cyclodextrin and fluoxetine were investigated by fluorescence spectrometry. A 1:1 stoichiometry of the complex was established and association constant of 4.35x10(-3) M(-1) at 20 degrees C was calculated. A spectrofluorimetric method for the determinati... | 18,968,754 |
Creatinine sensitive biosensor based on ISFETs and creatinine deiminase immobilised in BSA membrane. | A creatinine sensitive biosensor based on ion sensitive field-effect transistors (ISFETs) with immobilised creatinine deiminase (CD) is developed. CD is immobilised on the transducer surface by classical cross-linking with bovine serum albumin (BSA) in a glutaraldehyde (GA) vapour. The linear dynamic ranges of biosenso... | 18,968,760 |
Determination of lead and cadmium in titanium dioxide by differential pulse anodic stripping voltammetry. | A procedure for the simultaneous determination of lead and cadmium in TiO(2) by differential pulse anodic stripping voltammetry (ASV) has been developed. The key feature of the method is the use of triethanolamine (TEA) to remove titanium interference: TiO(2) undergoes acidic digestion with HF/H(2)SO(4) at atmospheric ... | 18,968,775 |
Measuring the transverse concentration gradient between adjacent laminar flows in a microfluidic device by a laser-based refractive index gradient detector. | A detection scheme that probes the refractive index gradient (RIG) between adjacent laminar flows in microfluidic devices has been developed and evaluated. The behavior of low Reynolds number flows has been well documented and shows that molecular transport (mixing) between adjacent laminar flows occurs by molecular di... | 18,968,783 |
A sulpha-drug sensitive sensor based on ion-pair complex modified PQC resonator. | The construction and general performance characteristics of the piezoelectric sensors responsive to sulpha-drug are described here. The proposed sensing method is based on the use of the ion-pair complex of sulphadiazine-cetyltrioctylammonium. The complex, together with cholestyramine was embedded in PVC matrix. This s... | 18,968,793 |
Determination of lysergic acid diethylamide (LSD) by application of online 77 K fluorescence spectroscopy and a sweeping technique in micellar electrokinetic chromatography. | The principal advantage of the use of Shopl'skii effect (low temperature spectrum) is that spectral sharpening occurs both in absorption and emission. However, thus far using the technique of capillary electrophoresis/low temperature fluorescence spectroscopy (CE/LTFS) either at 77 or 4.2 K remains difficult to obtain ... | 18,968,798 |
Simultaneous determination of uric acid and creatinine in urine by an eco-friendly solvent-free high performance liquid chromatographic method. | A simple, rapid, and eco-friendly analytical method for simultaneous determination of uric acid and creatinine in urine applying high performance liquid chromatography (HPLC) is described. After dilution, de-protein, and filtration, the sample solution was injected to separate the species with C-18 column by an eluent ... | 18,968,800 |
Voltammetric determination of diethylstilbestrol at carbon paste electrode using cetylpyridine bromide as medium. | In this paper, the voltammetric properties of diethylstilbestrol (DES) at the carbon paste electrode were described. The oxidation peak currents of DES increase significantly in the presence of surfactant cetylpyridine bromide (CPB), compared with that in the absence of CPB. Based on this fact, a voltammetric technique... | 18,968,804 |
N,N'-disalicylidene-1,3-diaminopropane as a selective chelating titrant for copper(II). | This study was carried out to develop a new complexometric titration method for determination of copper. For this purpose, the standard solutions of copper(II) (10(-3)-10(-5) M) were potentiometrically titrated using N,N'-disalicylidene-1,3-diaminopropane (Schiff base) as titrant and copper(II)-selective electrode for ... | 18,968,809 |
Potentiometric determination of antimony in metal(II) hexafluoroantimonates(V). | The purpose of this study was to develop an accurate and precise analytical procedure for the determination of the content of antimony in coordination compounds of metal(II) hexafluoroantimonates(V) (M(SbF(6))(2) compounds, where M=Mg, Ca, Sr or Ba) synthesized in our laboratory. The major problem was to find an approp... | 18,968,810 |
Long pathlength absorbance spectroscopy: trace copper analysis using a 4.4 m liquid core waveguide. | Procedures are described for measurement of dissolved copper with long pathlength Teflon AF-2400 liquid core waveguides. Using a 4.4 m waveguide, absorbance versus concentration is linear for copper concentrations between 1 and 160 nM. The molar absorbance of copper complexed with bathocuproine disulfonate is nearly id... | 18,968,821 |
Effects of different parameters on supercritical fluid extraction of steroid drugs, from spiked matrices and tablets. | Feasibility of supercritical CO(2) extractions of two steroid drugs, medroxyprogesterone acetate (med) and cyproterone acetate (cyp), were evaluated. The effects of temperature (308-348 K), pressure (100-300 bar), static extraction time (5-15 min), dynamic extraction time (10-30 min) and percent methanol modifier (1-10... | 18,968,834 |
Simple flow injection system for colorimetric determination of iodate in iodized salt. | This work presents a flow injection (FI) system that was developed for determination of iodate. The system utilizes the oxidation of iodide by the analyte to iodine, which subsequently forms tri-iodide. In the presence of starch, the blue I(3)(-)-starch complex is developed within the sample zone and can be colorimetri... | 18,968,857 |
Stopped-flow injection simultaneous determination of phosphate and silicate using molybdenum blue. | Kinetic information for the phosphate-molybdate-ascorbic acid reaction can be obtained by making use of a very simple manually operated stopped-flow injection (FI) system. Various parameters (concentrations of reagents, flow rate, mixing coils, and volume of flow cell) were investigated for determination of phosphate. ... | 18,968,871 |
Continuous-flow extraction system for elemental association study: a case of synthetic metal-doped iron hydroxide. | A continuous-flow extraction system originally developed for sequential extraction was applied to study elemental association of a synthetic metal-doped amorphous iron hydroxide phase. The homogeneity and metal association of the precipitates were evaluated by gradual leaching using the system. Leachate was collected i... | 18,968,876 |
SOLVERSTAT: a new utility for multipurpose analysis. An application to the investigation of dioxygenated Co(II) complex formation in dimethylsulfoxide solution. | A new utility for multipurpose analysis, SOLVERSTAT, taking advantage of the versatility of spreadsheets is here described. By means of this tool advanced statistical tests have introduced in Microsoft Excel Solver thus allowing regression diagnostic and discrimination between different models. The utility is here appl... | 18,968,885 |
A mercury(II) ion-selective electrode based on neutral salicylaldehyde thiosemicarbazone. | A new ion-selective PVC membrane electrode based on salicylaldehyde thiosemicarbazone as an ionophore is developed successfully as sensor for mercury(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear log[Hg(2+)] versus EMF response over a wide concentration range of 1... | 18,968,889 |
The quantification of sodium in mineral waters using a quartz crystal microbalance. | A sensor for sodium based on a piezoelectric quartz crystal is proposed. The quartz crystal was coated with 5% of bis[(12-crown-4)methyl] dodecylmethylmalonate, 33% of PVC and 62% of NPOE to which KTpClPB in a 22% molar proportion to the ionophore was added. Coating amounts producing a frequency decrease around 18 kHz ... | 18,968,905 |
Analysis of 2,4,6-trinitrotoluene, pentaerythritol tetranitrate and cyclo-1,3,5-trimethylene-2,4,6-trinitramine using negative corona discharge ion mobility spectrometry. | In this study, the capability of negative corona discharge ion mobility spectrometry (IMS) for quantitative magnitude of several explosives including 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN) and cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) has been evaluated for the first time. The total cu... | 18,968,915 |
Rapid sample digestion by fusion and chemical separation of Hf for isotopic analysis by MC-ICPMS. | A new method for rapid sample digestion and efficient chemical separation of Hf and REE from rock samples for precise isotopic analysis is presented. Samples are digested by fusion in the presence of a lithium borate flux at 1100 degrees C and dissolved whilst molten in dilute nitric or hydrochloric acid. Prior to chem... | 18,968,919 |
Application of a classical least-squares regression method to the assay of 1,4-dihydropyridine antihypertensives and their photoproducts. | A multicomponent UV spectrophotometric method using a classical least-squares (CLS) algorithm has been developed for the quantitative determination of 1,4-dihydropyridine (DHP) calcium antagonists and respective photoproducts. The procedure was optimized by defining a fractionation scheme for selecting the more useful ... | 18,968,920 |
Strategies for developing NADH detectors based on Meldola Blue and screen-printed electrodes: a comparative study. | Three strategies have been compared to produce screen-printed amperometric detectors for NADH: mixing Meldola Blue (MB) in the screen-printing ink, incorporation of MB-Reinecke salt (MBRS) in the graphite ink and electrodeposition of films of MB-derived polymer (poly (MB)) on electrode surface. Following modification o... | 18,968,963 |
Factorial designs applied to the development of a capillary electrophoresis method for the analysis of zinc, sodium, calcium and magnesium in water samples. | The aim of this work was to study the influence of several both chemical and instrumental variables for the development of a new capillary electrophoresis (CE) method for the determination of zinc, sodium, calcium and magnesium in water samples by using 1,10-phenanthroline as complexing agent and UV photometric detecti... | 18,968,965 |
Fast microwave-assisted free sugars washing and hydrolysis pre-treatment for the flow injection determination of starch in food. | The approach used consists of a flow injection (FI) manifold assisted by a focused microwave digestor for both fast washing of free sugars and acceleration of the hydrolysis step prior to the determination of starch in food. The action of microwaves reduces both the times for removal of free sugars to a 5 min single wa... | 18,968,971 |
Flow analysis-hydride generation-Fourier transform infrared spectrometric determination of antimony in pharmaceuticals. | In this work, a flow analysis system with hydride generation and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of antimony in pharmaceuticals. The method is based on the on-line mineralization/oxidation of the organic antimonials present in the sample and pre-reducti... | 18,968,981 |
Determination of matrine in rat plasma by high-performance liquid chromatography and its application to pharmacokinetic studies. | A simple high-performance liquid chromatography (HPLC) method is described for the determination of matrine in rat plasma. The plasma was deproteinized with acetonitrile that contained an internal standard (phenacetin) and was separated from the aqueous layer by adding sodium chloride. Matrine was extracted into the ac... | 18,968,986 |
Mercury(II) ion-selective polymeric membrane sensor based on a recently synthesized Schiff base. | A new polyvinyl chloride (PVC) membrane electrode that is highly selective to Hg(II) ions was prepared by using bis[5-((4-nitrophenyl)azo salicylaldehyde)] (BNAS) as a suitable neutral carrier. The sensor exhibits a Nernstian response for mercury ions over a wide concentration range (5.0x10(-2)-7.0x10(-7) M) with a slo... | 18,969,027 |
Acid-base equilibria of phthalic acid in saline media: ion association from Pitzer equations. | The protonation constants of 1,2-benzenedicarboxylic acid (phthalic acid) at 25 degrees C in NaCl and CaCl(2) (ionic strengths ranging from 0.1 to 2 mol kg(-1)) were determined potentiometrically, and the results were analyzed by means of Pitzer equations. The values of the logarithm of the first and second dissociatio... | 18,969,029 |
Evaluation of different permanent modifiers for the determination of arsenic in environmental samples by electrothermal atomic absorption spectrometry. | Single noble metal permanent modifiers such as, Rh, Ir, and Ru, as well as mixed tungsten plus noble metal (W-Rh, W-Ru, W-Ir) permanent modifiers thermally deposited on the integrated platform of transversally heated graphite atomizer were employed for the determination of arsenic in sludges, soils, sediments, coals, a... | 18,969,030 |
Analysis of polycyclic aromatic hydrocarbons in HPLC fractions by laser-excited time-resolved Shpol'skii spectrometry with cryogenic fiber-optic probes. | Laser-excited time-resolved Shpol'skii spectrometry at liquid helium temperature (4.2 K) is presented for the analysis of polycyclic aromatic hydrocarbons in high-performance liquid chromatography fractions. Fluorescence measurements are rapidly done with the aid of a fiber-optic probe, pulsed tunable dye laser, spectr... | 18,969,066 |
On-line screening methods for antioxidants scavenging superoxide anion radical and hydrogen peroxide by liquid chromatography with indirect chemiluminescence detection. | The identification of radical species is possible by the electron spin resonance technique. However, the antioxidants in complex matrices such as biological and food samples are difficult to determine. Hence, we developed novel screening systems for antioxidants, which are mainly eliminating superoxide anion radical (O... | 18,969,068 |
Fluorescence analysis of the interaction of two peptide sequences of hepatitis GB virus C with liposomes. | The physicochemical characterization of the peptide sequences E2 (39-53) and E2 (32-59) corresponding to the structural protein E2 of the GB virus C was done by studying their interaction with model membranes. The peptides showed surface activity concentration dependent when injected beneath a buffered solution. This t... | 18,969,070 |
Fluorometric assay of lipoperoxides and chromatographic analysis of alpha-tocopherol and fatty acids as biomarkers of risk from coronary atherosclerosis. | There has been growing interest in the quantitative determination of biochemical predictors of atherogenesis. The aim of the present study was to investigate association of lipoperoxidation biomarkers known to be pro-atherogenic (thiobarbituric acid reactive substance activity, TBARS) or anti-atherogenic (alpha-tocophe... | 18,969,072 |
A demonstration model for a selective and recyclable uptake of metals from water: Fe(III) ions complexation and release by a supported natural fluorescent chelator. | We describe here the preliminary stage of development of a process aiming at the selective uptake and release of metal ions from water. The process envisioned involves the encapsulation of highly selective natural chelates secreted by bacteria or other living species in mesoporous solids that could be used as usual res... | 18,969,073 |
Contributions to the determination of histamine rate by measuring out the histamine-orthophthalaldehyde complex in the absorption and fluorescence. | Histamine is an important compound from a physiological point of view, but it is toxic since the absorption of low amounts of histamine can cause abdominal pains accompanied with vomiting. Why we have developed a new method for histamine analysis in order to improve Lerke and Bell method. From the absorption spectra, w... | 18,969,080 |
Flow injection potentiometry by a new coated graphite ion-selective electrode for the determination of Pb(2+). | A new graphite coated electrode for the determination of Pb(2+) based on a recently synthesized ionophore 1-hydroxy-2-{2-[2-(2-hydroxy-ethoxy)-ethoxy]-ethoxy methyl}-anthracene-9,10-dione (L) has been developed. The electrode was used in flow injection potentiometry by a home-made flow cell. Under both the batch and fl... | 18,969,102 |
Molecular orientation of a model liquid crystal alignment layer. | An analytical methodology, involving the use of a combination of second harmonic generation (SHG) and linear dichroism, was utilized to probe the molecular orientation and angular distribution of a model liquid crystal (LC) alignment layer. In order to determine which film structure would be best suited for use as an a... | 18,969,104 |
Simultaneous determination of orthophosphate and total phosphates (inorganic phosphates plus purine nucleotides) using a bioamperometric flow-injection system made up by a 16-way switching valve. | Orthophosphate and total phosphates (inorganic phosphates plus purine nucleotides) can be determined simultaneously in a novel flow-injection system made up by a 16-way switching valve with two sample loops, acid phosphatase (AcP) immobilized reactor and a delay coil needed to separate two peaks corresponding to two sa... | 18,969,109 |
Application of flowing stream techniques to water analysis. Part I. Ionic species: dissolved inorganic carbon, nutrients and related compounds. | This paper summarizes the most relevant manuscripts issued from 1990 to date referred to water analysis using flowing stream techniques. Concretely, reported flow methods applied to the determination or monitoring of inorganic analytes (viz. carbon, nitrogen, phosphorous and silicon species) together with some related ... | 18,969,112 |
Selective pre-concentration of selenite from aqueous samples using mercapto-silica. | Silica gel modified with 3-mercaptopropyl-trimethoxysilane was used for the selective separation and pre-concentration of selenite (Se(IV)) from aqueous solutions containing Se(IV) and selenate (Se(VI)). Over a wide range of acidity, from 2 mol l(-1) HCl to pH 9.00, Se(IV) was taken up by the mercaptopropyl-silica with... | 18,969,126 |
Membrane electrodes sensitive to doubly charged surfactants. Application to a cationic gemini surfactant. | The response of a membrane electrode is not always identical to that of a redox electrode. Indeed, in the case of membrane electrode the response is not due to a redox equilibrium but to a cross-membrane potential. So, the membrane electrode's response depends mainly on the carrier system and the nature of the membrane... | 18,969,132 |
Two different strategies for the fluorimetric determination of piroxicam in serum. | Two different spectrofluorimetric methods for the determination of piroxicam (PX) in serum are presented and discussed. One of them is based on the use of three-way fluorescence data and multivariate calibration performed with parallel factor analysis (PARAFAC) and self-weighted alternating trilinear decomposition (SWA... | 18,969,137 |
Preparation of multiwall carbon nanotubes film modified electrode and its application to simultaneous determination of oxidizable amino acids in ion chromatography. | A multiwall carbon nanotubes (MWNTs) film modified electrode was prepared and used as an amperometric sensor for the simultaneous determination of oxidizable amino acids including cysteine, tryptophane and tyrosine. The electrochemical behaviors of these amino acids at this modified electrode were studied by cyclic vol... | 18,969,138 |
Determination of phosphate in hydroponic nutrient solutions using flow injection potentiometry and a cobalt-wire phosphate ion-selective electrode. | The direct flow injection potentiometric (FIP) analysis of phosphate in hydroponic nutrient solution has been carried out using a cobalt-wire ion-selective electrode (ISE). Synthetic hydroponic nutrient solution, commercial hydroponic nutrient solution and working hydroponic farm nutrient solution were analysed for pho... | 18,969,148 |
Novel flow injection-fluorometric method for the determination of trace silicate and its application to ultrapurified water analysis. | A highly sensitive fluorescence quenching method for the determination of silicate based on the formation of an ion associate between molybdosilicate and Rhodamine B (RB) in nitric acid medium was developed. A flow injection system coupled with a fluorescence detector was used for the measurement of fluorescence intens... | 18,969,155 |
Development of a catalase based biosensor for alcohol determination in beer samples. | An amperometric biosensor based on catalase enzyme for alcohol determination was developed. To construct the biosensor catalase was immobilized by using gelatin and glutaraldehyde on a Clark type dissolved oxygen (DO) probe covered with a teflon membrane which is sensitive for oxygen. The working principle of the biose... | 18,969,169 |
GFAAS determination of selenium after separation with thiol cotton in lichens and plants: the importance of adding a mineral matrix before decomposition. | This study reports a preparation technique for the determination of Se concentration in lichens and plants, using matrix separation and preconcentration of samples with thiol cotton. Sample digestions were done using HNO(3)-H(2)O(2)-HF. A graphite furnace atomic absorption method has been used for the determination of ... | 18,969,170 |
Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate-surfactant film modified electrode. | Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) were investigated successfully in liquid crystal films of didodecyldimethylammonium bromide (DDAB) on pyrolytic graphite (PG) electrodes in aqueous solution. This new bi-CoPc-surfactant film modified electrode co... | 18,969,184 |
Optimum phase-behavior formulation of surfactant/oil/water systems for the determination of chromium in heavy crude oil and in bitumen-in-water emulsion. | An "oil in water" formulation was optimized to determine chromium in heavy crude oil (HCO) and bitumen-in-water emulsion (Orimulsion-400(R)) samples by transversally heated electrothermal atomic absorption spectrometry (TH-ET AAS) using Zeeman effect background correction. The optimum proportion of the oil-water mixtur... | 18,969,194 |
Biosensors for phenol derivatives using biochemical signal amplification. | Two different approaches, both exploiting two enzymes cooperative functioning, to enhance the sensitivity of tyrosinase (PPO) based biosensor for amperometric detection of phenols have been compared. For this purpose, one monoenzyme electrode (PPO) and two bienzyme electrodes (PPO and d-glucose dehydrogenase, GDH; PPO ... | 18,969,212 |
A study of bismuth-film electrodes for the detection of trace metals by anodic stripping voltammetry and their application to the determination of Pb and Zn in tapwater and human hair. | This work reports the simultaneous determination of Cd(II), Pb(II) and Zn(II) at the low mug l(-1) concentration levels by square wave anodic stripping voltammetry (SWASV) on a bismuth-film electrode (BFE) plated in situ. The metal ions and bismuth were simultaneously deposited by reduction at -1.4 V on a rotating glas... | 18,969,224 |
The formation of sparingly soluble species of Ca(2+) with carboxylic ligands: speciation and thermoanalysis. | This work reports the results of studies into the solubility and thermal decomposition of various sparingly soluble complexes of calcium with two isomeric benzene tricarboxylates, and with benzene penta- and hexa-carboxylates. The dependence of their solubility on ionic strength and, for the calcium benzene hexacarboxy... | 18,969,225 |
Simultaneous determination of lead, nickel, tin and copper in aluminium-base alloys using slurry sampling by electrical discharge and multielement ETAAS. | The simultaneous multielement determination of Pb, Sn, Ni and Cu in aluminium alloys by electrothermal atomic absorption spectrometry (ETAAS) was performed by a quick method using slurry sampling. The metallic colloidal slurries were obtained by an electrical discharge operated in liquid medium. In this work, the effec... | 18,969,226 |
Cathodic stripping voltammetry of trace Mn(II) at carbon film electrodes. | A sensitive voltammetric method is presented for the determination of tract levels of Mn (II) using carbon film electrodes fabricated from carbon resistors of 2 Omega. Determination of manganese was made by square wave cathodic stripping voltammetry (CSV), with deposition of manganese as manganese dioxide. Chronoampero... | 18,969,228 |
Concentration of heavy metal ions in water using thermoresponsive chelating polymer. | Thermoresponsive polymers, poly(N-isopropylacrylamide) (PNIPAAm), having chelating functionalities were synthesized. PNIPAAm-imidazole (-Im) was precipitated and formed a gum-like aggregate in the neutral pH region at 50 degrees C, while PNIPAAm-carboxylic acid (COOH) and PNIPAAm-iminodiacetic acid (-IDA) remained solu... | 18,969,246 |
Copper(I)-bathocuproine complex as carrier in iodide-selective electrode. | A PVC membrane electrode for iodide ions based on Cu(I)-bathocuproine as ionophore in membrane composition is prepared. The electrode exhibits a linear response over a wide concentration range 5.0x10(-6) to 2.0x10(-1)moll(-1) with a detection limit 1.0x10(-6)moll(-1). The proposed membrane electrode shows Nernstian beh... | 18,969,284 |
Sulfonylcalix[4]arenetetrasulfonate as pre-column chelating reagent for selective determination of aluminum(III), iron(III), and titanium(IV) by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection. | Sulfonylcalix[4]arenetetrasulfonate (SO(2)CAS) has been examined as a pre-column chelating reagent for ultratrace determination of metal ions by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection. Metal ions were converted into the SO(2)CAS chelates in an acetic buffer solu... | 18,969,300 |
Selective labeling of histidine by a designed fluorescein-based probe. | The synthesis of a novel fluorescent probe, 3-epoxypropoxy fluorescein (EPF), and its properties for labeling of histidine are described. The probe contained a fluorescein fluorophore with long-wavelength response and an active epoxy labeling group. In alkaline media EPF reacted selectively with histidine, rather than ... | 18,969,304 |
Assessment of heavy metals leachability from metallo-organic sorbent-iron humate-with the aid of sequential extraction test. | The sequential extraction test, known as a BCR procedure, was used to assess a leachability of heavy metals (Zn, Cd, Pb, Cu) from the metallo-organic sorbent-iron humate-loaded with these metals. The sequential test allowed to discriminate between various fractions of heavy metals, namely the acid-extractable fraction,... | 18,969,324 |
Optimization of smoothing process-the method to improve calibration in voltammetry Part I. Simulated voltammograms. | The problem of the optimal choice of algorithmic filter and the evaluation of smoothing effects in voltammetry is studied. The basic idea of the optimization is an investigation of the improvement of the calibration and the recovery functions parameters during denoising process. The evaluation routine yields the answer... | 18,969,334 |
Synthesis and characterization of electrochemiluminescent ruthenium(II) complexes containing o-phenanthroline and various alpha-diimine ligands. | A series of o-phenanthroline-substituted ruthenium(II) complexes containing 2,2'-dipyridyl, 2-(2-pyridyl)benzimidazole, 2-(2-pyridyl)-N-methylbenzimidazole, 4-carboxymethyl-4'-methyl-2,2'-dipyridyl, and/or 4,4'-dimethyl-2,2'-dipyridyl ligands were synthesized and examined as potent electrochemiluminescent (ECL) materia... | 18,969,335 |
Simultaneous determination of tin, germanium and molybdenum by diode array detection-flow injection analysis with partial least squares calibration model. | Simultaneous determination of tin, germanium and molybdenum in food samples has been established by flow injection-charge coupled detector (CCD) diode array detection spectrophotometry with partial least squares (PLS) algorithm. The method was based on the chromogenic reaction of metal ions and salicylflurone in the pr... | 18,969,354 |
Fluorometric enzyme immunosensing system based on a renewable immunoreaction platform for the detection of Schistosoma japonicum antibody. | A fluoroimmunosensing device which was based on ferulic acid (FA)/horseradish peroxidase system for the detection of Schistosoma japonicum antibody (SjAb) has been developed. To circumvent the difficulty of regeneration of immunocomposite surface, a natural chitosan-epoxy resin matrix was used for the immobilization of... | 18,969,356 |
An intelligent flow analyser for the in-line concentration, speciation and monitoring of metals at trace levels. | An intelligent and versatile flow system is proposed for the in-line speciation and/or concentration of metal ions at a wide range of concentrations without requiring manifold reconfiguration. On one hand, sample enrichment strategies are accomplished using packed-bed reactors, on the other hand speciation procedures a... | 18,969,376 |
Arsenic speciation patterns in freshwater fish. | Muscle of 16 freshwater fish (9 different species belonging to 4 different families) was analysed for arsenic species using HPLC separation (anion and cation exchange) followed by on-line UV-decomposition, hydride generation and AFS detection. The main arsenic compounds found in the extracts were arsenobetaine (AsB), w... | 18,969,382 |
Second derivative spectrophotometric method for simultaneous determination of cobalt, nickel and iron using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. | A simple, sensitive and rapid derivative spectrophotometric method using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) has been developed for simultaneous determination of Co(II), Ni(II) and Fe(II) which have very similar chemical behavior and appear together in many real samples. The complexes of all thes... | 18,969,387 |
Fluorescence detection of cytosine/guanine transversion based on a hydrogen bond forming ligand. | In combination with abasic site (AP site)-containing oligodeoxynucleotides (ODNs), we demonstrate potential use of a hydrogen bond forming ligand, 2-amino-7-methyl-1,8-naphthyridine (AMND), for the fluorescence detection of the cytosine (C)/guanine (G) mutation sequence of the cancer repression gene p53. Our method is ... | 18,969,416 |
Spectrophotometric flow-injection determination of zinc in plant digests based on a spot test. | A spot test was implemented in a flow-injection system for the spectrophotometric determination of zinc in digests of plant materials. It is based on the influence of Zn(2+) on the oxidation rate of 1-naphthylethylenediamine (NED) by hexacyanoferrate(III) under acidic conditions. In order to control the precipitate for... | 18,969,424 |
Threshold bootstrap target factor analysis study of neodymium with pyridine 2,4 dicarboxylic acid N-oxide-an investigation of traceability. | Threshold bootstrap computer-assisted target factor analysis (TB CAT) has been applied to the evaluation of UV-Vis spectra of Nd(III) in aqueous solutions containing varying amounts of pyridine 2,4-dicarboxylic acid N-oxide (dipyr NO). Using the total uncertainty budget concept, probability distributions of the conditi... | 18,969,430 |
Electroanalytical method of TCPP and its supramolecular system with cyclodextrins. | In this paper, electroanalytical method of tetrakis (4-carboxylphenyl) porphyrin (TCPP) has been established. In a supporting electrolyte of KH(2)PO(4)-Na(2)HPO(4) (pH 7.0), a sensitive second derivative reduction peak of TCPP was found by single-sweep oscillopolarography. The potential peak is -0.70V (versus SCE).The ... | 18,969,472 |
Validation of the thermodynamic model of inorganic arsenic in non polluted river waters of the Basque country (Spain). | The thermodynamic model of inorganic arsenic was validated by comparing the predicted As(III) concentration with the experimentally determined one in several river waters samples of the Basque Country (Spain) collected in two sampling campaigns: spring and autumn 2000. This model takes into account the acid-base equili... | 18,969,487 |
Fluorescence and terbium-sensitised luminescence determination of garenoxacin in human urine and serum. | Fluorescence and terbium-sensitised luminescence properties of new quinolone garenoxacin have been studied. The fluorimetric method allows the determination of 0.060-0.600mugml(-1) of garenoxacin in aqueous solution containing HCl/KCl buffer (pH 1.5) with lambda(exc)=282nm and lambda(em)=421nm. Micellar-enhanced fluore... | 18,969,488 |
On-line microdialysis assay of l-lactate and pyruvate in vitro and in vivo by a flow-injection system with a dual enzyme electrode. | A flow-injection biosensor system with an on-line microdialysis sampling is proposed for the simultaneous assay of l-lactate and pyruvate in serum and rat brain. The dialysate collected in the sample loop by perfusing Ringer's solution through the microdialysis probe is automatically injected into the flow-injection li... | 18,969,498 |
Analytical investigation of calcium oxalate films on marble monuments. | This paper describes an analytical approach to investigate the origin of oxalate films on marble. Calcium oxalate films were collected on buildings of historical importance in Lucca and Pisa (Italy) and characterised by optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX)... | 18,969,524 |
Electroanalysis of dopamine at a gold electrode modified with N-acetylcysteine self-assembled monolayer. | Voltammetric behavior of dopamine (DA) on a gold electrode modified with the self-assembled monolayer (SAM) of N-acetylcysteine has been investigated, and one pair of well-defined redox peaks of dopamine is obtained at the SAM modified gold electrode. The oxidation peak current increases linearly with the concentration... | 18,969,533 |
Multiresidue determination of sulfonamides in a variety of biological matrices by supported liquid membrane with high pressure liquid chromatography-electrospray mass spectrometry detection. | A high performance liquid chromatography (HPLC) coupled to a mass spectrometer (MS) was used for a simultaneous determination of 16 sulfonamide compounds spiked in water, urine, milk, and bovine liver and kidney tissues. Supported liquid membrane (SLM) made up of 5% tri-n-octylphosphine oxide (TOPO) dissolved in hexyl ... | 18,969,572 |
Electrochemistry and scanning electron microscopy of polyaniline/peroxidase-based biosensor. | An amperometric biosensor was prepared by in situ deposition of horseradish peroxidase (HRP) enzyme on a polyaniline (PANI)-doped platinum disk electrode. The PANI film was electrochemically deposited on the electrode at 100mVs(-1)/Ag-AgCl. Cyclic voltammetric characterization of the PANI film in 1M HCl showed two dist... | 18,969,575 |
The separation and determination of nitrophenol isomers by high-performance capillary zone electrophoresis. | o-Nitrophenol, m-nitrophenol, and p-nitrophenol could well be separated by capillary zone electrophoresis (CZE) by only adjusting the run buffer with methanol. Efficiency up to 10(5) theoretical plates per meter was achieved. The effects of several important factors were investigated to find optimum conditions. The lin... | 18,969,578 |
Macrocyclic antibiotics as chiral selectors in the design of enantioselective, potentiometric membrane electrodes for the determination of l- and d-enantiomers of methotrexate. | Three enantioselective, potentiometric membrane electrodes (EPMEs) based on macrocyclic glycopeptide antibiotics-vancomycin and teicoplanin (modified or not with acetonitrile)-were proposed for the determination of l- and d-enantiomers of methotrexate (Mtx). The linear concentration ranges for the proposed enantioselec... | 18,969,580 |
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