title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Radioanalytical determination of actinides and fission products in Belarus soils. | Alpha emitting actinides such as plutonium, americium or curium were measured by alpha-spectrometry after radiochemical separation. The short range of alpha-particles within matter requires, after a pre-concentration process, a succession of isolation and purification steps based on the valence states modification of t... | 18,967,524 |
Determination of bismuth in biological samples using on-line flow-injection microwave-assisted mineralization and precipitation/dissolution for electrothermal atomic absorption spectrometry. | An on-line automated flow injection system with microwave-assisted sample digestion for the electrothermal atomic absorption spectrometric determination of bismuth in biological materials is described. After the exposure of the sample to microwave radiation, the analyte was subject to a precipitation/dissolution proces... | 18,967,531 |
Stopped-flow determination of dipyridamole in pharmaceutical preparations by micellar-stabilized room temperature phosphorescence. | The stopped flow mixing technique has been used to study the kinetic determination of dipyridamole by means of micellar-stabilized room temperature phosphorescence (RTP). This mixing system diminishes the time required for the deoxygenation of the micellar medium by sodium sulfite. The phosphorescence enhancers thalliu... | 18,967,550 |
Recent advances in the determination of the platinum group elements and gold. | Accurate determinations of the platinum group elements (PGEs) and gold, known as the precious metals, have always been difficult tasks. The metals are often present at trace levels in sample types of complex composition. This situation has improved recently due to developments of instrumental methods and their applicat... | 18,967,568 |
Solid-phase extraction and spectrophotometric determination of trace amounts of copper in water samples. | A simple method for rapid and selective extraction, preconcentration and determination of copper as it's neocuproine complex by using octadecylsilica membrane disks and spectrophotometry is presented. Extraction efficiency and the influence of flow rates of sample solution and eluent, pH, amount of neocuproine and hydr... | 18,967,582 |
Direct determination of bismuth, indium and lead in sea water by Zeeman ETAAS using molybdenum containing chemical modifiers. | Direct determination of Bi, In and Pb in sea water samples has been carried out by ETAAS with Zeeman background correction using molybdenum containing chemical modifiers and tartaric acid as a reducing agent. Maximum pyrolysis temperatures and the effect of mass ratios of the mixed modifier components on analytes have ... | 18,967,584 |
Normal-phase high-performance liquid chromatographic determination of spiramycin in eggs and chicken. | A precise method is presented for determination of residual spiramycin (SP) in chicken eggs and tissues by high-performance liquid chromatography (HPLC). The sample preparation was performed by homogenizing with a mixture of acetonitrile and n-hexane (5:4, v/v) to minimize the fat amount followed by ultra-filtration us... | 18,967,619 |
Asynchronous merging zones system: spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products. | An asynchronous merging zones was proposed with simultaneous introduction of the sample and of the modifier reagent, ascorbic acid in the studied case, for sequential determination of Fe(II) and Fe(III) in pharmaceutical products. The sample and reagent attained a merging point at different times owing to the use of a ... | 18,967,624 |
The use of 1-[pyridyl-(2)-azo]-naphthol-(2) in the presence of TX-100 and N,N'-diphenylbenzamidine for the spectrophotometric determination of copper in real samples. | A simple and sensitive field detection and spectrophotometric method for determination of copper described herewith is based on the formation of a red coloured species of copper(II) with 1-[pyridyl-(2)-azo]-naphthol-(2) (PAN), TX-100 and N,N'-diphenylbenzamidine (DPBA) at pH range 7.8-9.4. The red coloured Cu(II)-PAN-(... | 18,967,631 |
Electrochemical studies and square wave adsorptive stripping voltammetry of the antidepressant fluoxetine. | The electrochemical reduction of the antidepressant drug fluoxetine was investigated by cyclic, linear sweep, differential pulse and square wave voltammetry using a hanging mercury drop electrode in alkaline buffer solution in water and in a water/acetonitrile mixed solvent. Cyclic voltammograms in aqueous solution sho... | 18,967,637 |
pH-Metric determination of acid values in oilseeds without titration. | A new pH-metric method for determination of acid values in oilseeds without titration has been developed in the range 0.6-10 and more mg KOH/g. The method is based on a rapid (1-2 min) selective and complete extraction of free fatty acids from an oilseed test portion into a special reagent A, separation of the solution... | 18,967,639 |
In-situ external reflection FTIR spectroelectrochemical and XPS investigations of cobalt-cyanometallates as inorganic polymeric materials on a platinum electrode. | Cobalt-cyanometallate films electrochemically deposited on a platinum electrode were studied by cyclic voltammetry (CV), in-situ FTIR spectroelectrochemistry (FTIRs) and potential resolved XPS measurements. The experimental results reveal that the CoHCF film on Pt electrode exists in two forms. The major form of the in... | 18,967,647 |
Transport of organic dyes through ether-type polyurethane membrane. | Transport of various anthraquinone, acidic and basic dyes in aqueous solution through ether-type polyurethane membrane has been studied to better define the factors affecting the removal of organic compounds by the polyurethane membrane and to complement the previously proposed sorption mechanism. The effects of pH, sa... | 18,967,652 |
Modelling the matrix interference of iron in the multivariate determination of copper by stripping voltammetry Instrument standardization. | Two different standardization procedures have been applied in order to minimize the experimental effort necessary to determine copper in presence of iron by differential pulse anodic stripping voltammetry. The significant matrix interference caused by iron in the voltammetric determination of copper has been successful... | 18,967,656 |
Determination of Cu(II) and Zn(II) using silica gel loaded with 1-(2-thiasolylazo)-2-naphthol. | The silica gel with 1-(2-thiasolylazo)-2-naphthol adsorbed was obtained. The adsorption of Cu(II) and Zn(II) from an aqueous solution onto loaded silica gel was studied. The capabilities of 1-(2-thiasolylazo)-2-naphthol immobilized for Cu(II) and Zn(II) preconcentration, visual and diffusion reflectance spectroscopic d... | 18,967,666 |
Does the chromatomembrane cell improve the quality of environmental analysis? | With the intention of combining partition chromatography and membrane techniques, we succeeded in developing the chromatomembrane cell which has proved to be reliable as an extraction and preconcentration manifold in flow injection analysis. With this technique, two immiscible phases can be induced to flow independentl... | 18,967,674 |
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 ClO(3)(-)-ClO(2)(-) and ClO(3)(-)-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 det... | 18,967,677 |
Chromium speciation using an automated liquid handling system with inductively coupled plasma - mass spectrometric detection. | The speciation of inorganic chromium in environmental samples is required for accurate assessment of pollution levels. Of the two chromium oxidation states, Cr (VI) is a known carcinogen, while Cr (III) is an essential element. Total chromium measurement cannot be used to determine actual environmental impact due to th... | 18,967,681 |
Flow-injection spectrophotometry of manganese by catalysis of the periodate oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid). | A sensitive flow-injection spectrophotometric procedure is proposed for the determination of manganese(II), based on its catalytic effect on the oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with periodate. By monitoring the change in absorbance of the oxidation product of ABTS at 415 nm, ma... | 18,967,685 |
Speciation of arsenic and selenium compounds by HPLC hyphenated to specific detectors: a review of the main separation techniques. | This review deals with liquid phase separation of major arsenic and selenium species followed by element specific detection. It concerns papers published since 1980 and describing only currently used methods that were or could be applied to As and Se speciation in environmental matrices. Methods performances are compar... | 18,967,689 |
A miniaturized urea sensor based on the integration of both ammonium based urea enzyme field effect transistor and a reference field effect transistor in a single chip. | A urea biosensor prepared by covalent binding of urease directly to the surface of an ammonium-sensitive field effect transistor (FET) is described. Nonactin incorporated in carboxylated polyvinyl chloride was used to obtain the sensitive membrane of the ammonium-sensitive FET. The grafting of urease on the polyvinylch... | 18,967,711 |
Poly(vinyl chloride)-based macrocyclic membrane sensors for magnesium. | Poly(vinyl chloride)-based membranes of macrocycles 4,11-dimethyl-2,4,9,11-tetraethyl-1,5,8,12-tetraaza cyclotetradeca-1,8-diene (I) and 4,11-dioxa-2,9-dimethyl-1,5,8,12-tetraaza cyclotetradeca-1,8-diene (II) with sodium tetraphenyl borate (STB) as an anion excluder and dibutyl phthalate (DBP), dioctyl phthalate (DOP),... | 18,967,740 |
Determination of tungsten in niobium-tantalum, vanadium and molybdenum bearing geological samples using derivative spectrophotometry and ICP-AES. | Two different procedures, one using derivative spectrophotometry and another using inductively coupled plasma atomic emission spectrometry (ICP-AES) have been developed for the determination of tungsten in niobate-tantalates, tin slag samples, ores, concentrates and vanadium and molybdenum bearing geological materials.... | 18,967,758 |
Complexation and determination of palladium (II) ion with para-Cl-phenylazo-R-acid spectrophotometrically. | The complexation of para-Cl-phenylazo-R-acid azo dye with Pd(II) has been studied spectrophotometrically. Protonation constant (pK(a)) of the ligand has been calculated and the stability conditional constants of para-Cl-phenylazo-R-acid ligand with palladium ion has been determined at a constant temperature (25.0 degre... | 18,967,771 |
Sequential injection spectrophotometric assay of bromazepam complexed with iron(II) in hydrochloric acid with chemometric optimization. | A sequential injection spectrophotometric method for the assay of bromazepam anxiolytic drug has been reported. The method is based on the complexation reaction of bromazepam with iron(II) in hydrochloric acid media and spectrophotometrically measuring the product at lambda(max)=585 nm. A comprehensive chemometrical op... | 18,967,774 |
Pushing the detectability of voltammetry: how low can we go? | The coupling of adsorptive accumulation with catalytic reactions results in remarkably low (sub-picomolar) detection limits. This review assesses various strategies for attaining such dual-amplification effects, that lead to the most sensitive voltammetric technique, adsorptive-catalytic stripping voltammetry (AdCtSV). | 18,967,784 |
On the acid behaviour of the alcoholic group of serine. | The behaviour of l-serine in strongly alkaline solution was studied at 25 degrees C and in 3.00 mol/l NaClO(4), as a constant ionic medium, to obtain quantitative information about the eventual dissociation of its alcoholic group. A spectrophotometric method was employed to measure the free concentration of hydrogen io... | 18,967,793 |
pH-Metric method for acid number determination in hydraulic oils without titration. | A heptane-mediated extraction of acids from hydraulic oils is proposed for pH-metric acid number determination without titration. The acids are extracted in the reagent consisting of triethanolamine and potassium nitrate dissolved in water and isopropanol. The use of heptane allows us to overcome the influence of addit... | 18,967,808 |
Copper determination in natural water samples by using FAAS after preconcentration onto amberlite XAD-2 loaded with calmagite. | A procedure for separation and preconcentration of trace amounts of copper in natural water samples, has been proposed. It is based on the adsorption of copper(II) ions onto a column of Amberlite XAD-2 resin loaded with calmagite reagent. This way amounts of copper within the range from 0.0125 to 25.0 microg, in a samp... | 18,967,821 |
(C70)2-p-tert-butylcalix[6]arene complex films on electrodes catalyze the reduction of nitrite ions. | (C70)(2)-p-tert-butylcalix[6]arene complex films on GC electrode surface showed two couples of redox reactions in mixed solvent of (1:1, v:v) acetonitrile and water containing tetra-butylammonium perchlorate. The electrocatalytic reduction for nitrite by these films was observed, indicating that (C70)(2)-p-tert-butylca... | 18,967,827 |
Simultaneous determination of manganese and zinc in mixtures using first- and second-derivative spectrophotometry. | A new direct spectrophotometric determination of manganese with 5,8-dihydroxy-1,4-naphthoquinone (naphthazarin,NAZA) is reported. Absorption maximum, molar absorptivity and Sandell's sensitivity of 1:2 (M:L) complex are 695 nm, 1.88x10(4) l mol(-1) cm(-1) and 2.92 ng cm(-2), respectively. A linear calibration graph is ... | 18,967,835 |
Donnan dialysis of copper, gold and silver cyanides with various anion exchange membranes. | Donnan dialysis is an ion exchange membrane process that can be used for the purification and concentration of diluted solutions. In this work, the behaviour of gold, silver and copper in cyanide medium is examined. Flux of cyanide complexes and corresponding free cyanide are determined using five commercial anion exch... | 18,967,859 |
Analysis of archaeological samples and local clays using ICP-AES, TG-DTG and FTIR techniques. | The spectrochemical and thermal analysis of different archaeological samples as bricks, terra-cotta and local clays were carried out. The concentration of major and minor elements of samples was determined by sequential inductively coupled plasma atomic emission spectrometry. The method was tested by determining Si, Al... | 18,967,866 |
Simultaneous determination of ethanol and glycerol in wines by a flow injection-pervaporation approach with in parallel photometric and fluorimetric detection. | A simultaneous method for the determination of ethanol and glycerol in wines based on the coupling of pervaporation-chemical derivatisation-photometric detection for ethanol and biochemical derivatisation-fluorimetric detection for glycerol is proposed. After separation by pervaporation the ethanol is collected in a K(... | 18,967,879 |
Enrichment of benzo[a]pyrene in vegetable oils and determination by HPLC-FL. | We have developed a simple method for the determination of the carcinogen Benzo[a]pyrene (BP) in vegetable oils. The method consists of extraction of the vegetable oil in acetonitrile, concentration to dryness in rotary evaporator and redissolution of the residue in hexane. The purification of the hexane extract was on... | 18,967,938 |
Application of H-point standard additions method to spectrophotometric and spectrofluorimetric determinations of glafenine and glafenic acid in mixtures. | H-point standard additions method (HPSAM), based on spectrophotometric and spectrofluorimetric measurements, was proposed for simultaneous determination of glafenine (G) and glafenic acid (GA). A study of the absorption spectra of G and GA in various pH media has been carried out. Reasonably resolved UV-absorption spec... | 18,967,954 |
Potentiometric determination of dialysate urea nitrogen. | An enzymatically modified ammonium ion-selective electrode has been applied for the determination of urea in spent dialysate. The biosensor has been used in a simple flow-injection analysis (FIA) system. The system enables one to perform over 25 dialysate urea nitrogen (DUN) determinations per hour. The interferences f... | 18,967,957 |
Sequential injection system for the spectrophotometric determination of reducing sugars in wines. | A sequential injection system for the spectrophotometric determination of reducing sugars in wines is described. The methodology is based on the formation of a coloured complex produced by the reaction of copper (I) with 2,9-dimethyl-1,10-phenanthroline (neocuproine), after reduction of copper (II) to copper (I) by red... | 18,967,962 |
Determination of antibacterial reagents by liquid chromatography-electrospray-mass spectrometry. | This paper describes a newly developed liquid chromatography-electrospray-mass spectrometry (HPLC-ES-MS) method for the determination of 13 antibacterial reagents (olaquindox, trimethoprim, clopidol, ormethoprim, morantel, carbadox, thiamphenicol, pyrimethamine, furazolidone, oxolinic acid, difurazon, nalidixic acid, p... | 18,967,971 |
Flow injection determination methods of ascorbic acid. | A review with 100 references is presented to show the advantages involved in the use of flow injection analysis (FIA) for the determination of ascorbic acid. The FI methods proposed for the determination of ascorbic acid are described and compared according to the used detection technique. Analytical figures of merit a... | 18,967,995 |
Selectivity assessment of a sequential extraction procedure for metal mobility characterization using model phases. | This study considers the selectivity of the extractants used in a sequential extraction scheme for metals mobility assessment by analyzing individual mineral phases previously coprecipitated or sorbed with trace metals. The scheme evaluated was a modification of the Tessier et al. [A. Tessier, P.G.C. Campbell, M. Bisso... | 18,968,015 |
On the improvement of solid-phase extraction room-temperature phosphorimetry for the analysis of polycyclic aromatic hydrocarbons in water samples. | This article presents considerable improvements in SPE-RTP methodology for the analysis of polycyclic aromatic hydrocarbons in water samples. Bulky glassware and vacuum pump were removed from the previous extraction procedure [E.D. Hagestuen, A.D. Campiglia, Talanta 49 (1998) 547] by processing 10 ml of sample with syr... | 18,968,032 |
Atomic absorption spectrometric determination of calcium and other metallic elements in some animal protein sources. | The phosphorus content of some animal protein sources was determined in order to identify the sample with the highest phosphorus content for use as a pilot sample. Varying concentrations of strontium and lanthanum were added to solutions of the ashed pilot sample for the determination of calcium and magnesium using fla... | 18,968,034 |
Radiosensitivity study of cefazolin sodium. | The extent of physico-chemical changes induced by irradiation of cefazolin sodium was investigated. The methods used were potency determination, impurity profile, colour measurements and pH measurements. The potency of irradiated samples at 25 kGy was 4+/-2% lower than that of the non irradiated ones. The total amount ... | 18,968,047 |
Conductometric determination of carbon in uranium carbide and its solution in nitric acid. | A simple but accurate method has been developed for the determination of carbon in uranium carbide powders/pellets as well as in solutions of uranyl nitrates. The methodology involves quantitative conversion of carbon present in the sample to carbon dioxide that is subsequently absorbed in a dilute solution of barium h... | 18,968,049 |
A long path length spectroelectrochemical behavior analysis of the coabsorption system. | The coabsorption system in which both species Red and Ox absorb at the same wavelength was investigated by the long path length spectroelectrochemical technique. The variation of the system absorbance at the isosbestic point with time, which is strongly dependent upon the diffusion coefficients and their difference, wa... | 18,968,051 |
The role of manganese(IV) compounds as oxidants - a review. | A historical review of the development of manganese(IV) chemistry and its application in analytical chemistry is presented. A brief presentation of the presence and importance of manganese(IV) in other areas of chemistry is also given. | 18,968,056 |
Determination of trace metal ions by AAS in natural water samples after preconcentration of pyrocatechol violet complexes on an activated carbon column. | A simple preconcentration method is described for the determination of Cu, Mn, Co, Cd, Pb, Ni and Cr in water samples by flame AAS. Trace metal ions in water were sorbed as pyrocatechol violet complexes on activated carbon column at the pH range of 4-8, then eluted with 1 M HNO(3) in acetone. The effect of major cation... | 18,968,065 |
Oxidation at a sol-gel composite electrode doped with a dirhodium-substituted polyoxometalate for amperometric detection of peptides separated by HPLC. | Oxidation of a variety of compounds, including methionine (Met), using a complex formed between dirhodium(II) acetate and the lacunary form of phosphotungstic acid as the catalyst is effective over a wide range of conditions, including pH 2-10. Thus, amperometric detection at a composite in which this complex is immobi... | 18,968,070 |
Effect of concentration of ion exchanger, plasticizer and molecular weight of cyanocopolymers on selectivity and sensitivity of Cd(II) ion selective electrode. | Potential response of cadmium(II) ion selective electrode based on cyanocopolymer matrices and 8-hydroxyquinoline as ionophore has been evaluated by varying the amount of ionophore, plasticizer and the molecular weight of the cyanocopolymer. The sensitivity, working range, response time, and metal ions interference hav... | 18,968,071 |
Determination of clenbuterol in pharmaceutical preparations by reaction with o-phthalaldehyde using a flow-injection fluorimetric procedure. | A new procedure for the determination of clenbuterol is proposed using flow-injection and fluorimetric detection. The method is based on the derivatization reaction of the primary amine group with o-phthalaldehyde in the presence of 2-mercaptoethanol. The calibration graph based on peak area was linear in the range 0.2... | 18,968,087 |
Isolation and structural characterization of a pectin homo and ramnogalacturonan. | With a purpose to achieve an individual components of the pectins there was purified and separated the acidic components of the apple pectin and its chemical structure was studied using (13)C-NMR-Spectroscopy. The apple pectin was consecutively subjected to processing with hydrochloric acid and ethanol mixture, ultrace... | 18,968,102 |
Simultaneous derivative spectrophotometric determination of cobalt(II) and nickel(II) by dithizone without extraction. | Dithizone (Dz), a common extractive-photometric ligand for Co(II) and Ni(II), has been dissolved in the water-miscible solvent tetrahydrofurane (THF) so as to constitute a reagent for both metals in aqueous phase without extraction. Complex formation was complete for both metals at pH 12.0 (adjusted by aqueous NH(3)) w... | 18,968,111 |
Coulometric detector based on porous carbon felt working electrode for flow injection analysis. | A coulometric detector based on carbon felt as working electrode has been designed. Ascorbic acid, hydroquinone, gallic acid and sulfur dioxide were used as electroactive compounds to determine the electrochemical characteristics of this detector. The coulometric conversion efficiency, selectivity, linear response rang... | 18,968,153 |
Ensuring complete absence of Ce(IV) and measurement of the stability constant of the fluoride complex of Ce(III). | Literature survey revealed a wide variation in the measured stability constant values of the aqueous fluoride complexes of trivalent cerium. This could be due to inadequate care for full conversion and maintenance of the oxidation state of cerium to trivalent state. In the present work quinhydrone has been used to ensu... | 18,968,159 |
Construction and evaluation of ion selective electrodes for nitrate with a summing operational amplifier. Application to tobacco analysis. | In this paper, the construction and evaluation of an electrode selective to nitrate with improved sensitivity, constructed like a conventional electrode (ISE) but using an operational amplifier to sum the potentials supplied by four membranes (ESOA) is described. The two types of electrodes, without an inner reference ... | 18,968,163 |
Room-temperature phosphorescence of 6-bromo-2-naphthol included in beta-cyclodextrin in the presence of cyclohexane. | The formation constant for a 1:1 binary complex between 6-bromo-2-naphthol (6B2N) and beta-cyclodextrin (CD) in aqueous solution was determined by both absorptimetric and fluorimetric methods. Room-temperature phosphorescence (RTP) was induced by adding small amounts of different apolar liquids as the third component, ... | 18,968,175 |
Chemiluminescence determination of some fluoroquinolone derivatives in pharmaceutical formulations and biological fluids using [Ru(bipy)(3)(2+)]-Ce(IV) system. | A new chemiluminescence (CL) method using flow injection has been described for the rapid and sensitive determination of three fluoroquinolone derivatives, namely ofloxacin, norfloxacin and ciprofloxacin hydrochloride. The method is based on the CL reaction of the studied fluoroquinolones with tris(2,2'-bipyridyl)ruthe... | 18,968,179 |
Synthesis of a novel chemiluminescent reagent for the determination of hydrogen peroxide in snow waters. | 7-(4,6-Dichloro-1,3,5-triazinylamino)-4-methylcoumarin (DTMC) was synthesized as a completely new chemiluminescent reagent, and with it a novel chemiluminescence method was developed for the determination of hydrogen peroxide in the absence of any added catalyst or co-oxidant. The chemiluminescence intensity of the DTM... | 18,968,188 |
Determination of the herbicide desmetryne in organised media by adsorptive stripping voltammetry. | An electroanalytical method for the determination of the herbicide desmetryne at nanomolar levels in dispersed media, based on adsorptive stripping voltammetry, is reported. The adsorption of desmetryne at the hanging mercury drop electrode was checked both in micellar solutions, where the anionic surfactant sodium pen... | 18,968,189 |
Influence of pH and fluoride concentration on titanium passivating layer: stability of titanium dioxide. | Titanium and titanium alloy biomaterials are considered as being corrosion resistant, because of the formation of a titanium oxide passivating layer, which is not easily soluble even in acid media. In odontology, using dental preparations containing fluorides could alter the behaviour of titanium. After a review of the... | 18,968,197 |
Effect of structural modifications of diaza-18-crown-6 on the extractability and selectivity of univalent metal picrates. | The solvent extraction of univalent metal cations with N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16 diaza-2,3,11,12-dibenzocycloocta deca-2,11-diene (L(1)), N,N' didodecyl-1,4,10,13-tetraoxa-7,16-diaza-2,3-benzocylooctadeca-2 ene (L(2)) and N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16 diaza-2,3,11,12-dibenzocyclo octadeca-2,11-diene... | 18,968,200 |
Electrochemical detection of thiols in biological media. | The utilisation of catechol as an electrochemical indicator for the presence of sulphydryl thiols (RSH) has been investigated. The electrochemical oxidation of the catechol within tissue culture media was examined with the influence exerted on the redox chemistry by cysteine evaluated in terms of the development of an ... | 18,968,201 |
Preconcentration of traces of gold, silver and palladium on activated carbon and its determination in geological samples by flame AAS after wet ashing. | A simple, rapid and cost effective preconcentration method is described for the determination of traces of gold (Au), silver (Ag) and palladium (Pd) in geological samples by flame atomic absorption spectrophotometry (AAS). The method is based on sorption of analytes (Au, Ag and Pd) on powdered activated carbon (AC) at ... | 18,968,206 |
Flow injection spectrophotometric analysis of lead in human saliva for monitoring environmental pollution. | A new highly sensitive, simple and low-cost methodology for the direct determination of Pb (II) with 2-(5-bromo-2-pyridylazo)-5-dimethylaminophenol in ethanolic medium has been developed. The absorption spectroscopy of the complex has been examined in detail, and the chemical variables affecting the sensitivity of proc... | 18,968,224 |
On the possibility to improve the performance of flow injection analysis by deconvolution of spectrophotometric data. | The concentration profile of chemical species pumped through a tubular system of 0.5-mm inner diameter is found to be trapezial shaped, as described theoretically by including the spatial resolution of the instrument, friction and diffusion. By applying the theory, which is based on the concept of segment flow, to expe... | 18,968,234 |
Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation. | A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a col... | 18,968,235 |
Determination of ketorolac in human serum by square wave adsorptive stripping voltammetry. | The adsorption behavior of ketorolac on a hanging mercury drop electrode (HMDE) was explored by square-wave and cyclic voltammetry. The square wave voltammetric response of ketorolac depends on the parameters of the square wave voltammetry excitation signal as well as on the pH of the medium and the accumulation time. ... | 18,968,250 |
A study on the interaction between concanavalin A and glycogen by light scattering technique and its analytical application. | The mixture of concanavalin A (Con A) and glycogen shows strong light scattering character. Based on it, the interaction between Con A and glycogen was studied on a common spectrofluorimeter by light scattering technique. Many factors affecting the light scattering intensity (LSI), such as pH, temperature, reaction tim... | 18,968,256 |
New method for separation and determination of denatured caseins by hydrophobic interaction chromatography. | A new method for the separation of denatured alpha-, beta- and kappa- caseins by hydrophobic interaction chromatography (HIC) is proposed. The method is based on an easy solubilization of commercial and real samples by 4.0 M guanidine thiocyanate (GdmSCN) and elution on a TSK-Gel(R) Phenyl-5PW column (TosoHaas) in the ... | 18,968,257 |
An insight into the solution equilibria of magnesium(II) with purpurin and spectrophotometric determination of magnesium. | The complexation equilibria of magnesium(II) with purpurin (PURP) are studied spectrophotometrically as a function of pH in 50% (v/v) ethanol-water medium at 20 degrees C. The uncharged complex formed at pH 9.5 allows precise and accurate determination of magnesium over the concentration range 0.8-4.3 mug ml(-1). The m... | 18,968,260 |
Redox-potentiometric determination of peroxide value in edible oils without titration. | Standard methods for peroxide value determination in edible oils, which are based on KI oxidation by the hydroperoxides and volumetric titration of the liberated iodine, have been improved using redox-potentiometric iodine determination without titration. Stages of the KI oxidation and redox-potentiometric measurements... | 18,968,266 |
Screening people for illicit substances: a survey of current portal technology. | The need to implement more effective, cost efficient, non-intrusive ways of screening people for concealed drugs, explosives and weapons is a major security initiative for the U.S. and elsewhere. A new generation of portals suitable for security checkpoints is under development. These will be able to find contraband wi... | 18,968,270 |
Selective dissolution and one step separation of terpene trilactones in ginkgo leaf extracts for GC-FID determination. | Under ultrasonication, the ginkgo terpene trilactones, ginkgolides and bilobalide, in ginkgo extracts can be selectively dissolved in 10% aqueous NaH(2)PO(4) solution at a temperature of 50-60 degrees C and separated from the solution by extraction with a mixture of ethyl acetate/tetrahydrofuran in a capped vial. After... | 18,968,289 |
Effects of fungal laccase immobilization procedures for the development of a biosensor for phenol compounds. | Fungal laccase was immobilized on carbon-fiber electrodes using classical methods: physical adsorption, glutaraldehyde, carbodiimide and carbodiimide/glutaraldehyde. The highest biosensor response was obtained using carbodiimide/glutaraldehyde for coupling laccase to carboxyl groups on the carbon fibers. In this method... | 18,968,290 |
Application of the H-point standard addition method to the speciation of Fe(II) and Fe(III) with chromogenic mixed reagents. | Simultaneous determination of Fe(II) and Fe(III) or selective determination of each oxidation state of iron in the presence of the other one by H-point standard addition method (HPSAM) is described. Mixed reagents of 1,10-phenanthroline and salicylic acid was used as a selective chromogenic system for speciation of Fe(... | 18,968,295 |
Urea biosensor based on amperometric pH-sensing with hematein as a pH-sensitive redox mediator. | The natural dye hematein in water solution was used as a pH-sensitive redox-active mediator for amperometric pH-sensing. The electrochemical characteristics were studied using cyclic voltammetry and chronoamperometry. Several types of urea biosensors were constructed with urease on the surface of platinum and graphite ... | 18,968,299 |
PVC membrane based potentiometric sensors for uranium determination. | Two novel uranyl PVC matrix membrane sensors responsive to uranyl ion are described. The first sensor incorporates tris(2-ethylhexyl)phosphate (TEHP) as both electroactive material and plasticizer and sodium tetraphenylborate (NaTPB) as an ion discriminator. The sensor displays a rapid and linear response for UO(2)(2+)... | 18,968,336 |
The study of PVP/Pd/IrO(2) modified sensor for amperometric determination of sulfur dioxide. | A novel electrochemical sensor for the detection of sulfur dioxide in both gas and solution is described. The chemically modified electrode was constructed by polymerizing (4-VP), palladium and iridium oxide (PVP/Pd/IrO(2)) onto a platinum microelectrode which exhibits excellent catalytic activity toward sulfite with a... | 18,968,366 |
A simple vapour phase decomposition (VPD) of quartz powder in a polypropylene vessel and determination of phosphorus by spectrophotometry. | A simple, low pressure, low temperature vapour phase decomposition (VPD) of quartz powder has been developed for the determination of phosphorus. A platinum dish containing the quartz or silicon powder was placed inside a polypropylene vessel containing 40 ml of 1:1 mixture of HF and HNO(3). After capping the vessel, t... | 18,968,395 |
Analysis of selenium species by capillary electrophoresis. | The presence of selenium in the form of different species in environmental and biological samples receives an increasing attention due to better understanding of its bioavailability, toxicity and transport mechanism. For many years, gas and liquid chromatography have been extensively explored in speciation analysis of ... | 18,968,412 |
Determination for micro amounts of nucleic acids by a resonance light scattering technique with dequalinium chloride. | Based on the strong enhancement effect of nucleic acids on resonance light scattering of dequalinium chloride, the determination method for micro amounts of nucleic acids has been developed. Under the experimental conditions (5.0x10(-5) mol l(-1) dequalinium, pH 7.0, at room temperature) the linear range of this assay ... | 18,968,413 |
Comparisons of sorption of aquatic humic matter by DAX-8 and XAD-8 resins from solid-state (13)C NMR spectroscopy's point of view. | Aquatic humic solutes were separated in parallel by the non-ionic macroporous DAX-8 and XAD-8 resins from four different fresh water sources. On average, the sorptive power of the DAX-8 resin does not differ systematically from that of the XAD-8 resin. The DAX-8 resin seems to have more precise column characteristics c... | 18,968,420 |
Determination of trace amounts of heavy metals in arctic ice core samples using inductively coupled plasma mass spectrometry. | Trace amounts of heavy metals in the ice cores from Canadian Arctic were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). A custom made plastic device and ceramic knives were used to remove the contamination on the ice core surface. Ice cores could be broken into small sections (2-3 cm thick) after... | 18,968,423 |
Application of solid-phase microextraction for the determination of organophosphorous pesticides in aqueous samples by gas chromatography with flame photometric detector. | A method based on solid-phase microextraction and gas chromatography flame photometric detector for the determination of organophosphorous pesticides (OPPs) in aqueous samples was described. Five kinds of commercially available fibers-7, 30 and 100 mum PDMS, 85 mum PA and 65 mum PDMS-DVB-were compared and 100 mum PDMS ... | 18,968,428 |
Development of piezoelectric immunosensors for measurement of albuminuria. | The development of piezoelectric immunosensors for human serum albumin (HSA) is reported. The piezoelectric crystals were modified either with monoclonal antibody AL-01 (direct assay) or with HSA (competitive assay). Measurements were carried out in the flow-through mode. Affinity interaction between albumin and the an... | 18,968,431 |
A multicommutation-based flow system for multi-element analysis in pharmaceutical preparations. | A flow system exploiting multicommutation and multidetection is proposed for sequential determinations in pharmaceutical preparations. The feasibilities were demonstrated by the determination of zinc, iron, copper, calcium and magnesium without changing the flow set-up. The gravitational flow of the solutions was explo... | 18,968,435 |
Recombinant single chain antibodies in bioelectrochemical sensors. | Recombinant antibodies provide an emerging strategy in the development of new immunosensors. In particular, single chain antibodies (scFvs) can be isolated and expressed in bacterial systems that also allow their in vitro manipulation at the gene level. In this work, we present for the first time results of single-chai... | 18,968,440 |
Multibiosensor based on enzyme inhibition analysis for determination of different toxic substances. | An original concept of an enzyme multibiosensor for determination of toxic substances based on enzyme inhibition analysis has been proposed and its main performances have been analysed. For the development of this multibiosensor, two types of transducers such as potentiometric pH-sensitive field-effect transistors and ... | 18,968,442 |
Flow injection chemiluminescence determination of polyhydroxy phenols using luminol-ferricyanide/ferrocyanide system. | It was found that the weak chemiluminescence produced from the reaction of polyhydroxy phenols with luminol in alkaline solution could be strongly enhanced by ferricyanide and ferrocyanide. Based on this found, a new flow injection chemiluminescence method is proposed for the determination of four polyhydroxy phenols: ... | 18,968,456 |
Maleic acid-styrene encapsulated silica cation exchanger in high performance liquid chromatography. | The use of poly(maleic acid-styrene)-encapsulated silica for the determination of monovalent and divalent cations is well accepted in ion chromatography. The separation of Mn(2+), alkali and alkaline earth metal cations is obtained under the same chromatographic conditions. The influences of pH and the concentration of... | 18,968,461 |
Kinetics of europium(III) transport through a liquid membrane containing HEH(EHP) in kerosene. | Coupled transport of Eu(III) ions through a bulk liquid membrane containing mono(2-ethylhexyl)2-ethylhexyl phosphonate [HEH(EHP)] in kerosene has been examined. The influences of the carrier concentration, the HCl concentration in the stripping solution, the pH in the feed solution and the temperature were investigated... | 18,968,464 |
A high precision spectrophotometric method for on-line shipboard seawater pH measurements: the automated marine pH sensor (AMpS). | Measurement strategies for understanding the oceanic CO(2) (carbon dioxide) system are moving towards in situ and ship of opportunity sampling techniques. Automated instrumentation with high accuracy and sampling frequencies will enable a greater understanding of the fluxes of marine carbon and lead to a more reliable ... | 18,968,480 |
Fast determination of lead in lake sediment samples using electrothermal atomic absorption spectrometry with slurry samples introduction. | Lead concentration in lake sediment samples has been determined by means of ultrasonic slurry sampling electrothermal atomic absorption spectrometry USSS-ETAAS. The soil samples were suspended (0.025-0.15% w/v slurry) in four different liquid media containing 0.5% (v/v) nitric acid, 5% (v/v) nitric acid, 0.5% nitric ac... | 18,968,485 |
Identification and simultaneous determination of Azorubin, Allura red and Ponceau 4R by differential pulse polarography: application to soft drinks. | Azorubin (E 122), Ponceau 4R (E 124) and Allura red (E 129), are the most used red dyes in soft drinks manufacturing, and in some cases two dyes are present. The aim of this work is to show that using differential pulse polarography, it was possible to distinguish these synthetic dyes from the natural dyes providing fr... | 18,968,486 |
Sample pretreatment on microfabricated devices. | The integration of sample pretreatment into microfluidic devices represents one of the remaining hurdles towards achieving true miniaturized total analysis systems (muTAS). The challenge is made more complex by the enormous variation in samples to be analyzed. Moreover, the pretreatment technique has to be compatible w... | 18,968,499 |
A microfabricated amperometric moisture sensor. | We describe a microfabricated moisture sensor with interdigitated Au or Pt electrodes on a silicon substrate. The sensor active area is covered with a spin-coated, baked-on layer of Nafion(R) perfluorosulfonate ionomer of submicron thickness. The sensor responds to moisture with a 10-90% rise time of 50-100 ms and a 90... | 18,968,503 |
A biosensor for monitoring formaldehyde using a new lipophilic tetrathiafulvalene-tetracyanoquinodimethane salt and a polyurethane membrane. | A format for a disposable screen-printed biosensor was investigated for monitoring formaldehyde. The screen-printed sensor format comprised a working electrode (WE) modified with platinised carbon, a new lipophilic tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) salt as mediator, a plasticised polyurethane membr... | 18,968,517 |
Chemiluminescence muTAS for the determination of atropine and pethidine. | A novel chemiluminescence micro-total analytical system (muTAS) is described for the determination of atropine and pethidine. Reagents were moved though the 200-mum wide channels of a glass chip using a negative pressure pumping system. Linear calibrations were obtained for the system over three-orders of magnitude, wi... | 18,968,526 |
Ruthenium(II) tris(bipyridyl) ion as a luminescent probe for oxygen uptake on the catalyzed oxidation of HSO(3)(-). | The present work describes an alternative technique for monitoring the rate of oxygen consumption during the oxidation of HSO(3)(-) catalyzed by manganese and iron ions. The method is based on the spectrofluorimetric monitoring of the quenching effect of molecular oxygen on the emission of the photoexcited [Ru(bipy)(3)... | 18,968,527 |
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