title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Determination of antimony in lead-zinc concentrates and other smelter products by atomic absorption spectrometry after extraction with di-isopropyl ether and reductive stripping. | Several papers have appeared in the literature describing the determination of antimony, where antimony(V) is extracted into the organic phase and the organic solutions directly analyzed by atomic absorption spectrometry (AAS). This paper describes a procedure where antimony from the organic solution is reductively str... | 18,966,445 |
Simultaneous determination of penicillin and ampicillin by spectral fibre-optical enzyme optodes and multivariate data analysis based on transient signals obtained by flow injection analysis. | A multicomponent detection system using optical biosensors and flow injection analysis is described. The analysis of mixtures containing penicillin and ampicillin was realised by evaluating dynamic measurements of Phenol Red spectra in penicillinase optodes in combination with a diode array spectrometer. A variety of o... | 18,966,453 |
PA.FPNS: its synthesis and use in spectrophotometric determination of magnesium. | A new polymeric chromogenic reagent PA.FPNS has been synthesized by condensing polyallylamine (PA) with 3-(4-formylphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (FPNS) and its properties studied. In alkaline media, PA.FPNS reacts with magnesium to form a water-soluble blue complex, whose absorption maximum is... | 18,966,458 |
Study of complex formation in the manganese(II)/azide system. | The complex formation between Mn(II) cations and N(3)(-) anions was studied in aqueous medium at 25 degrees C and ionic strength 2.0 M (NaClO(4)). Data of average ligand number, n (Bjerrum's function), were obtained from pH measurements on the Mn(II)/N(3)(-)/HN(3) system followed by integration to obtain Leden's functi... | 18,966,464 |
Chemiluminescence flow sensor for the determination of ascorbic acid with immobilized reagents. | A novel flow sensor based on chemiluminescence (CL) for the determination of ascorbic acid has been proposed. The analytical reagents, luminol and ferricyanide, were both immobilized on an anion-exchange resin column. The CL signal produced by the reaction between luminol and ferricyanide, which were eluted from the co... | 18,966,471 |
Determination of trace nitrite ion in water by spectrophotometric method after preconcentration on an organic solvent-soluble membrane filter. | A simple and rapid preconcentration technique, based on collecting trace nitrite on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to its spectrophotometric determination in water. At pH 2.0, nitrous acid diazotizes with p-aminoacetophenone. which is then coupled with N-(1-... | 18,966,476 |
Enzyme sensors for determination of fish freshness. | A simple and rapid procedure for the determination of fish freshness was developed and applied to the determination of the K(1) parameter (freshness indicator): K(1) = ([HXR] + [HX])/([IMP] + [HXR] + [HX]) x 100, where [IMP], [HXR] and [HX] are inosine monophosphate, inosine and hypoxanthine concentrations, respectivel... | 18,966,489 |
Polarographic determination of mitoxantrone in pharmaceutical preparations and biological media. | An A.c. tast polarographic method for the determination of mitoxantrone in pharmaceutical preparations and biological media is described. The optimum pH for the extraction of the drug from various samples into a 4:1 mixture of chloroform-isopropanol is indicated. The effect of other parameters such as temperature, comp... | 18,966,501 |
Determination of total fluorine in five coal reference materials by proton-induced gamma-ray emission spectrometry. | The direct non-destructive proton-induced gamma-ray emission (PIGE) technique with a germanium detector was applied to the determination of total fluorine concentration in five coal reference materials (BCR 40, NIST 1632b, NIST 1635, SARM 20 and USGS CLB-1). Duplicate analyses were made from five randomly selected bott... | 18,966,506 |
Influence of ionic strength and OH(-) ion concentration on the Cu(II) complex formation with EDTA in alkaline solutions. | D.c. polarographic data show that the complex formation of copper ions with EDTA depends markedly on the ionic strength of the solution at pH 8-10. This is primarily associated with the dependence of the fourth deprotonization constant of EDTA on the solution ionic strength: when it increases from 0.4 to 3.4, the pK(a4... | 18,966,509 |
Combination of classical dry ashing with stripping voltammetry in trace element analysis of biological materials: review of literature published after 1978. | Critical statements have appeared recently in the literature concerning the need for classical dry ashing in trace element analysis of biological materials. In contrast, respected institutions (AOAC, Nordic Committee on Food Analysis, etc.) as well as numerous other laboratories have developed, verified, and/or success... | 18,966,515 |
Acid-base equilibria in gamma-butyrolactone studied by use of pH-ISFETs. | pH-ISFETs were used in the study of acid-base equilibria in gamma-butyrolactone (GBL). After the spectrophotometric determination of the pK(a) value of 3,5-dichloropicric acid, the pK(a) values and homo-conjugation constants of various acids (including the conjugate acids of bases) were determined potentiometrically us... | 18,966,530 |
A thin liquid film thickness shear mode bulk acoustic wave sensor for determination of Proteus mirabilis. | A thickness shear mode bulk acoustic wave sensor coated with a thin liquid culture medium film was developed and applied to determine the concentration of Proteus mirabilis (P. mirabilis). Experiments demonstrated that there was a good linear relationship between the turning point time and the logarithm of the P. mirab... | 18,966,534 |
Monitoring CP-93,393 reaction mixtures by flow-injection analysis-mass spectrometry. | CP-93,393 is a drug candidate at Pfizer. Flow-injection analysis-mass spectrometry (FIA-MS) was used to monitor reaction completion for CP-93,393 reaction mixtures. FIA-MS provides essentially instantaneous results, is relatively simple to operate, and is a universal system that can be used to monitor any reaction as l... | 18,966,555 |
Electroinjection analysis. The introduction of a new variant of flow-injection analysis and comparison with electrophoretically-mediated microanalysis. | A new method of mixing sample and reagent due to the difference in their electrophoretic mobilities is introduced. Unlike electrophoretically-mediated microanalysis, sample and reagent are injected from the opposite ends of a capillary tube. This method is compared with electrophoretically-mediated microanalysis. Exper... | 18,966,561 |
Coprecipitation with disulfide for the determination of traces of cobalt in water by electrothermal atomic absorption spectrometry. | Nanogram quantities of cobalt (II) in 200 ml of water were quantitatively collected at pH 4 on a precipitate of disulfide, which is an oxidation product of dithiol (toluene-3,4-dithiol). The precipitate was separated by filtration and dispersed homogeneously in 2 ml of 0.05 mol l(-1) nitric acid with the aid of ultraso... | 18,966,590 |
Adaptation of microthermal probes for the determination of biochemical species. | A glucose sensitive enzymatic thermal sensor based on a pair of commercial microthermal probes was fabricated by cross-linking of the corresponding enzymes (glucose oxidase and catalase) with bovine serum albumin onto the chip surfaces. The characteristics of this sensor were optimised by testing it in different condit... | 18,966,595 |
Microwave-assisted sample preparation in analytical chemistry. | The speed and efficiency of instrumentation for chemical analysis has improved dramatically over the past twenty years. Until recently, however, methods of sample preparation had not changed to keep pace, so this had become the slowest step in analytical chemistry methodology. The widespread adoption of domestic microw... | 18,966,599 |
Measurement/data-processing method to improve the ruggedness of membrane-based sensors: Application to amperometric oxygen sensor. | This paper describes alternative measurement and data-processing approaches that can reduce effects of experimental variables on results obtained with a membrane-based sensor for oxygen. In the new approaches, the membrane-based sensor is first equilibrated with the sample solution, after which a polarizing voltage is ... | 18,966,615 |
Electrocatalytic modified electrode for remote monitoring of hydrazines. | A remote electrochemical sensor for field monitoring of hydrazine compounds is described. The new submersible probe relies on the coupling of an effective electrocatalytic modified electrode to a 50 ft long shielded cable. The catalytic surface, based on an electorpolymerized film of 3.4-dihydroxybenzaldehyde, offers l... | 18,966,616 |
Phase inversion cellulose acetate membranes for suppression of protein interferences in anodic stripping voltammetry 2(1). Improvement of the membrane preparation procedure. | Phase inversion (PI) cellulose acetate membranes were cast on glassy carbon electrodes from a solution containing acetone as solvent and aqueous magnesium perchlorate as pore former. It is shown that a significant improvement of the reproducibility and permselective properties of the membrane is obtained by allowing co... | 18,966,617 |
Effect of alkyl substitueras in hydrophobic 8-quinolinol on the extraction of gallium(III) and applications to the separation of gallium(III) from aluminum(III). | The extraction of gallium(III) with newly prepared 5-alkyloxymethyl-8-quinolinol derivatives with alkyl substituent at the 2-position in 8-quinolinol moiety has been studied. The Ga(III)-5-octyloxymethyl-8-quinolinol (HO(8)Q), Ga(III)-2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q), Ga(III)-2-methyl-5-hexyloxymethyl-8... | 18,966,627 |
Medium effect on acidity constants of some heterocyclic nitrogen azomethines. | The effects of different organic solvent-water mixtures on the acidity constants of some azomethines derived from 3-amino-1,2,4-triazol; 2-amino-1,3-pyrimidine and also 2-amino-4-methyl-1,3-pyrimidine have been examined. Two pK(a) values for the o-OH derivatives were determined; one is assigned to the deprotonation of ... | 18,966,630 |
A series expansion of the extended Debye-Hückel equation and application to linear prediction of stability constants. | The Debye-Hückel semiempirical extended equation is frequently used to calculate activity coefficients of chemical species and equilibrium constants at ionic strengths different from those used in their experimental evaluation. A series expansion of the extended Debye-Hückel equation is proposed here and checked with e... | 18,966,639 |
Spectrophotometric determination of bio-active compounds with chloramine-T and gallocyanine. | A simple, sensitive and selective method for the spectrophotometric determination of drugs, viz., sulphamethoxazole, tetracycline HCl, amidopyrine, nifurtimox and isoniazid and biologically important amino acids, cysteine, aspartic acid and arginine based on their reactivity with chloramine-T (CAT) is proposed. The met... | 18,966,644 |
Chemiluminometric method for the determination of glycerol in wine by flow-injection analysis with co-immobilized glycerol dehydrogenase/NADH oxidase. | A flow-injection method for the determination of glycerol in wine is described. Glycerol dehydrogenase and NADH oxidase were co-immobilized on poly (vinyl alcohol) beads and incorporated in a flow-injection system. The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate (III) re... | 18,966,663 |
Fiber optic sensor for laser-induced room-temperature phosphorescence detection of polycyclic aromatic compounds. | The development of a fiber optic sensor for the analysis of polycyclic aromatic compounds based on laser-induced room-termperature phosphorimetry is reported for the first time. A pulsed nitrogen laser was used to excite phosphorescence emission from compounds imbibed on filter-paper substrates. Thallium(I) acetate (0.... | 18,966,667 |
Ultraviolet spectrophotometric determination of copper in copper ores by flow-injection analysis. | A flow-injection analysis (FIA) method for the ultraviolet spectrophotometric determination of copper in copper ores is described. The ore samples are dissolved in concentrated perchloric acid, the excess acid is neutralized with ammonia solution, and the resulting solution is used for the determination of copper. The ... | 18,966,680 |
Utility of quercetin for determination of some tertiary amine and quaternary ammonium salts. | A simple and sensitive spectrophotometric method for the assay of eight drugs containing quaternary ammonium or tertiary amine moieties is described. The method is based on the interaction of these drugs with quercetin after its oxidation with N-bromosuccinimide (as counter ion) to give highly colored ion-pairing compl... | 18,966,683 |
Automatic determination of cobalt at the submicrogram per millilitre level using a flowthrough spectrophotometric sensor. | A flowthrough spectrophotometric sensor for the determination of cobalt at the nanogram per millilitre level using pyridoxal 4-phenylthiosemicarbazone as reagent and integrated preconcentration and detection in the flow cell is proposed. The method is highly selective for cobalt(II); it features detection and determina... | 18,966,684 |
Extraction and determination of crown ethers from water samples using a membrane disk and gas chromatography. | A method for rapid extraction and determination of some crown ethers in aqueous matrices using octadecyl-bonded silica membrane disks and gas chromatography is presented. Extraction efficiency and the influence of vacuum pressure. pH, and type and least amount of eluting solvent used to extract the crown ethers from th... | 18,966,705 |
Determination of nanogram levels of zirconium by chelating ion exchange and on-line preconcentration in flow injection UV-visible spectrophotometry. | Trace quantities of zirconium were preconcentrated on a series of chelating resins. The experimental conditions for preconcentration such as pH, time and metal ion concentration were optimized for the batch processes. Continuous flow manifolds were developed for the on-line preconcentration of zirconium using microcolu... | 18,966,749 |
Solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302. | A rapid method was developed for the solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302 in chloroform as the diluent. Iron(III) was quantitatively extracted at pH 2.0-2.5 with 5 x 10(-3) M Cyanex 302 in chloroform whereas the extraction of aluminium(III) was quantitative i... | 18,966,775 |
Solubility of metal chelates and their extraction from an aqueous environment via supercritical CO(2). | Solubility of nickel(II), copper(II), and chromium(III) hexafluoroacetylacetone and chromium(III) acetylacetone chelates was measured in supercritical CO(2) at two different pressures (200 and 400 atm) and 60 degrees C. Solubility of fluorinated acetylacetone chelates was at least an order of magnitude higher than the ... | 18,966,798 |
Flotation-spectrophotometric determination of trace of germanium with isochromatic dye ion-pairs formed by rhodamine 6G and tetrabromofluorescein. | A flotation spectrophotometric method for the determination of germanium with isochromatic dye ion-pairs is described. The molar ratio of germanium to rhodamine 6G to tetrabromofluorescein is 1:5:5. The apparent molar absorptivity is 5.8 x 10(5) l mol(-1) cm(-1) at 531 nm. Beer's law is obeyed over the concentration ra... | 18,966,829 |
Determination of trace amounts of some metals in samples with high salt content by atomic absorption spectrometry after cobalt-diethyldithiocarbamate coprecipitation. | A method for determination of trace amounts of Cu, Fe, Pb, Mn, Zn, Cd, Ni, Bi and Cr in aqueous solutions by flame atomic absorption spectrometry after coprecipitation by using a combination of sodium diethyldithiocarbamate as a chelating agent and cobalt as a carrier element was introduced. Different factors including... | 18,966,833 |
Investigation of conductometric humidity sensors. | Sensors for determining humidity in air have been described and investigated. Sensing film of the devices was prepared from polyvinylalcohol and graphitized carbon black disperse phase. The composition, thermal treatment and design of sensing films were investigated and optimized. An optimized humidity sensor has bette... | 18,966,843 |
Fibre-optic pesticide biosensor based on covalently immobilized acetylcholinesterase and thymol blue. | A fibre-optic based on immobilized acetylcholinesterase is described and its application in the detection of carbamate and organophosphate pesticides through enzyme inhibition measurements is discussed. The bioactive component of the sensor consists of acetylcholinesterase covalently immobilized on preactivated isothio... | 18,966,870 |
Spectrophotometric determination of hydrogen peroxide by using the cleavage of Eriochrome black T in the presence of peroxidase. | A new hydrogen donor for peroxidase, Eriochrome black T, was reported for the first time. Steady-state catalytic velocity depends upon enzyme and substrate concentrations, and a Michaelis-Menten K(m) value of 1.72x10(-5) mol l(-1) and a V(max) value of 4.43x10(-3) s(-1) were measured at pH 8.6. Trace amount of hydrogen... | 18,966,877 |
Preparation and analytical properties of a chelating resin functionalized with 1-hydrazinophthalazine ligand. | A poly[styrene-co-(divinylbenzene)] resin (XAD-4) functionalized with 1-hydrazinophthalazine ligand has been prepared and its analytical properties investigated. The pH dependence of sorption of metal ion on the resin has been determined for Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Pb(II), Fe(III) and Cr(III). Trace amo... | 18,966,882 |
Amperometric monitoring of lactate accumulation in rabbit ischemic myocardium. | Fabrication and characterization of miniature, flexible, planar biosensors for monitoring l-lactate accumulation in an ischemic myocardium are described. Three configurations of Au-based electrodes were fabricated by a photolithographic technique on flexible polyimide Kapton((R)) foil. All sensors are based on an immob... | 18,966,893 |
Calibration procedure for solid phase microextraction-gas chromatographic analysis of organic vapours in air. | A calibration procedure for solid phase microextraction-gas chromatographic (SPME-GC) analysis of organic vapours in air was described in which GC detector (MS in this case) signal is directly related to concentration of analytes of interest sampled by SPME. Gaseous standard mixtures used for the calibration were gener... | 18,966,894 |
Utilization of standards generated in the process of thermal decomposition chemically modified silica gel for a single point calibration of a GC/FID system. | The utilization of a multicomponent gaseous standard mixture, containing CO and CO(2) and obtained by thermal decomposition of a so-called immobilized compound, for a single point calibration of a GC/FID system are described. The generation of such a mixture takes place as a result of thermal decomposition of a sample ... | 18,966,895 |
Chemometric alternatives for resolution of classical analytical problems Spectrophotometric determination of lanthanide mixtures. | The simultaneous determination of lanthanide family elements is one of the greatest problems in analytical chemistry, due to the close similarity of their chemical properties. Spectrophotometric methods are generally of limited use, due to the various mutual spectral interferences involved. By using multivariate calibr... | 18,966,922 |
Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam. | Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam... | 18,966,928 |
Gas chromatographic determination of pollutants in the chlorination and caustic extraction stage effluent from the bleaching of a bamboo pulp. | The gas chromatographic detection and quantitative determination of various chlorophenolics as well as resin and fatty acids have been carried out in the chlorination and caustic extraction stage effluents generated in the laboratory by bleaching a bamboo pulp. A number of chlorinated phenols, catechols, guaiacols, syr... | 18,966,933 |
Potentiometric determination of stability constants of Lanthanon(III) complexes with some Schiff bases and benzothiazolines. | The protonation constants of five Schiff base and two benzothiazoline type ligands and stability constants of their complexes with six lanthanide ions were determined by potentiometrically in ethanol-water solution (1:1, v/v) at 25 +/- 0.1 degrees C. The Schiff base-type ligands were salicylidene 2-iminopyridine (SAPy)... | 18,966,937 |
Multicomponent analysis in luminescence spectroscopy. | Multicomponent analysis of absorption spectra (infrared or electronic spectra) by factor analysis is a suitable method to use. The algorithm of factor analysis is now available for luminescence spectroscopy. The first possibility, as in absorption spectroscopy, is to determine pure components emission spectra for a uni... | 18,966,973 |
Quantitative calibration of vapor levels of TNT, RDX, and PETN using a diffusion generator with gravimetry and ion mobility spectrometry. | A prototype generator for creating a continuous stream of explosive vapor was referenced quantitatively both to a standard weight from the National Institute of Standards and Technology (NIST) and to the response of an ion mobility spectrometer. Vapors from solid explosive, in a precision bore glass tube at constant te... | 18,966,981 |
Characterization of an enzyme linked immunosorbent assay for Aflatoxin B(1) based on commercial reagents. | Two indirect ELISA have been investigated for the determination of Aflatoxin B(1), employing only reagents commercially available, whose composition is not exactly known. In both cases the antigen (Aflatoxin B(1)-BSA) was coated to the solid phase (polystyrene microtiter plates). In one procedure the specific antibody ... | 18,966,984 |
Application of chelation ion chromatography to the determination of lanthanides in agriculture. | Lanthanides are widely present in soil and plant. In this paper, it is the first time that chelation ion chromatography is applied to analyse lanthanides in a series of samples in agriculture. This technique can eliminate bulk quantity of alkali, alkaline earth metals on chelating concentrator column (MetPac CC-1) and ... | 18,966,987 |
Investigation of a flat sheet membrane desolvator for aqueous solvent removal with inductively coupled plasma atomic emission spectrometry. | Results obtained from a preliminary investigation of the performance of a flat sheet membrane desolvator (FSMD) utilizing dual hydrophobic polypropylene membranes with an average pore size of 0.05 mum and a 50 +/- 5 mum thickness are reported. The membranes have a desolvation area of 241 cm(2). The volume-to-surface ar... | 18,966,989 |
Ion-selective electrode for bismuth(III) in ethylenediamintetraacetate medium. | A coated graphite-epoxy ion-selective electrode for bismuth(III), based on the ion-pair between the [Bi(EDTA)](-) anion and tricaprylylmethylammonium cation (Aliquat 336S) incorporated onto a poly(vinylchloride) (PVC) matrix is constructed. A thin membrane film of this ion-pair, dibutylphthalate (DBPh) or ortho-nitroph... | 18,966,999 |
The extraction of uranium by amidoximated orlon. | The nitrile groups in polyacrylonitrile (Orlontrade mark) fabric were converted to amidoxime groups to produce an amidoximated orlon fabric. The amidoximated fabric was evaluated for its ability to extract uranium from aqueous solution with a wide range of temperature and pH values. The conversion of nitrile groups to ... | 18,967,000 |
Potentiometric flow injection determination of amylase activity by using hexacyanoferrate(III)-hexacyanoferrate(II) potential buffer. | A highly sensitive potentiometric flow injection determination of amylase activity was carried out, utilizing a redox reaction of hexacyanoferrate(III) in alkaline media with reducing sugar as product of the enzymatic hydrolysis reaction of starch with amylase. The analytical method is based on the potential change det... | 18,967,038 |
Purification of metallothionein proteins from the crab, Portunus pelagicus-selectivity of hydrophobic interaction chromatography. | Both hydrophobic interaction chromatography (HIC) and ion-exchange chromatography (IEC) are commonly used for the purification of proteins as their mild elution conditions preclude the dangers of denaturation. Of the two methods, IEC which fractionates proteins on the basis of charge differences, exhibits a higher sele... | 18,967,051 |
AFM imaging and characterization of latex particles formed by copolymerization of styrene and poly(ethylene oxide) macromonomer. | A new type of latex particle was prepared by copolymerization of styrene and poly(ethylene oxide) macromonomer. By controlling the concentration of styrene in reaction mixtures, several latexes with different grain sizes were obtained. The packing patterns of the latex films as well as shapes and sizes of the latex par... | 18,967,060 |
Use of time-resolved lanthanide-sensitized luminescence for the kinetic determination of p-aminobenzoic acid. | Lanthanide-sensitized luminescence was for the first time used to develop a simple kinetic method for the determination of p-aminobenzoic acid. The method is based on the formation of a complex with terbium(III) in the presence of trioctylphosphine oxide as synergistic agent and Triton X-100 as micellar medium. The hig... | 18,967,067 |
Sulphuric acid influence on liquid-liquid extraction of Co(II) and Zn(II) by MIBK from NH(4)SCN medium. | Liquid-liquid extraction of Co(II) and Zn(II) by methylisobutylcetone (MIBK) has been studied systematically from NH(4)SCN/H(2)SO(4) media. The influence of sulphuric acid concentration on the percentage of extraction of Co(II) and Zn(II) has been discussed. It is shown that sulphuric acid concentration has not the sam... | 18,967,073 |
Transport of Cu(II) with hydroxamic acid through a liquid membrane. | N-Hydroxy-N-naphthylbenzamides (3) were synthesized for examining their ability to extract and transport Cu(II) through a liquid membrane. The transport was proton-driven and was capable of moving metal ions ;up-hill'. Thus, it was possible to follow the transfer of Cu(II) from the aqueous source phase to the organic l... | 18,967,085 |
Simultaneous determination of propranolol and pindolol by synchronous spectrofluorimetry. | The simultaneous determination of propranolol and pindolol using synchronous fluorescence spectrometric techniques is described. The method involves measuring the natural fluorescence of these drugs in a 50% (v/v) ethanol-water medium using zero and first derivative synchronous spectrofluorimetry. Under the optimum con... | 18,967,086 |
Multivariate calibration applied to synchronous fluorescence spectrometry. Simultaneous determination of polycyclic aromatic hydrocarbons in water samples. | Synchronous fluorescence spectra of mixtures containing ten polycyclic aromatic hydrocarbons (anthracene, benz[a]anthracene, benzo[a]pyrene, chrysene, fluoranthene, fluorene, naphthalene, perylene, phenanthrene and pyrene) have been used for the determination of these compounds by Partial Least Squares Regression (PLSR... | 18,967,097 |
Chemiluminescent determination of pyridoxine hydrochloride in pharmaceutical samples using flow injection. | A chemiluminescent method using flow injection is described for the determination of pyridoxine hydrochloride. Its detection limit, linearity and reproducibility were examined. The method is based on the enhancing effect of pyridoxine hydrochloride on the chemiluminescence generated by the oxidation of luminol with hyd... | 18,967,105 |
Determination of aluminium and manganese in human scalp hair by electrothermal atomic absorption spectrometry using slurry sampling. | Methods for the determination of aluminium and manganese in human scalp hair samples by electrothermal atomic absorption spectrometry using the slurry sampling technique were developed. Palladium and magnesium nitrate were used as chemical modifiers. Hair samples were pulverized using a zirconia vibrational mill ball, ... | 18,967,107 |
Use of zirconium oxychloride to neutralize HF in the microwave-assisted acid dissolution of ceramic glazes for their chemical analysis by ICP-OES. | The use of a zirconium compound (ZrOCl(2)) to neutralize HF in the microwave-assisted acid dissolution of ceramic glazes for their chemical analysis was tested. Zr is a strong complexing agent for the fluorine ion and permits the determination of those elements which would form insoluble fluorides. The use of Zr implie... | 18,967,112 |
Possibilities for speciation of Al-citrate and other negatively charged Al complexes by anion-exchange FPLC-ICP-AES. | An anion-exchange fast protein liquid chromatographic-inductively coupled plasma atomic emission spectrometric procedure (FPLC-ICP-AES) was developed for speciation of Al-citrate and other negatively charged Al complexes. FPLC separations were carried out on a Mono Q HR 5/5 strong anion-exchange FPLC column over a pH r... | 18,967,147 |
Analysis for metallothioneins using coupled techniques. | Analytical chemistry of metallothioneins based on the coupling of a high resolution separation technique with an element or species selective detection technique is discussed. The role of size-exclusion chromatography (SEC) with on-line atomic spectrometric detection for the quantification of metallothionein fraction i... | 18,967,150 |
Use of microwave digestion for estimation of heavy metal content of soils in a geochemical survey. | A procedure for the rapid and safe analysis of soils with widely differing organic matter contents has been investigated and validated. Surface soils, totalling 295 and sampled on a grid basis, representing 22% of the land-base of the Republic of Ireland, have been analysed for cadmium, chromium, copper, nickel, lead a... | 18,967,164 |
Sensitivity and selectivity of electrochemical enzyme sensors for inhibitor determination. | The performance of electrochemical biosensors developed for the determination of inhibiting species is considered. The role of various factors affecting the analytical characteristics of biosensors, their selectivity toward inhibitors to be tested as well as operational characteristics is discussed. The choice of enzym... | 18,967,167 |
Extraction of phenols using polyurethane membrane. | The extraction of various phenols from aqueous and organic solutions using polyurethane membrane has been investigated. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. The phenols are extracted as neutral species and the extraction is governed... | 18,967,171 |
Determination of trace europium based on new fluorimetric system of europium(III) with thenoyltrifluoroacetone and N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide. | In the present paper, N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide acts as a specific reagent for enhancing the fluorescence intensity of Eu(III) complex with thenoyl trifluoroacetone (TTA), the spectrofluorimetric determination of trace amounts of Eu(III) based on the above system was carried out and its lumin... | 18,967,173 |
Spectrophotometric determination of methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) as enzymatic source. | A rapid, precise and low cost spectrophotometric method is proposed for the determination of methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxi... | 18,967,177 |
Direct determination of copper and zinc in cow milk, human milk and infant formula samples using electrothermal atomization atomic absorption spectrometry. | Infant formula and powdered milk samples were suspended in a medium containing 20% ethanol, 0.65% nitric acid, 6% hydrogen peroxide and 0.1% ammonium dihydrogenphosphate and directly introduced in the electrothermal atomizer. Liquid milk samples were diluted with this suspension solution. The build-up of carbonaceous r... | 18,967,184 |
Methods for determination of hexachlorobenzene and pentachlorophenol in soil samples. | The efficiency of methods for the determination of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil samples was evaluated. An on-line method was applied for HCB determination. Soil samples were transferred to chromatographic columns prepacked with alumina. The HCB elution was processed with n-hexane. The PCP... | 18,967,213 |
Complexation of trivalent cations (Al(III), Cr(III), Fe(III)) with two phosphonic acids in the pH range of fresh waters. | The complex formation constants of two phosphonic acids, HEDP and ATMP, with three trivalent metallic cations, Al(III), Cr(III) and Fe(III), have been determined by acid-base titration at 25 degrees C and constant ionic strength (0.1 mol l(-1), KNO(3)), using Martell and Motekaitis' computer programs. Species distribut... | 18,967,224 |
Multivariate analysis of Cd(II), In(III), Tl(I) and Pb(II) in mixtures using square wave anodic stripping voltammetry. | Accurate qualitative and quantitative results were obtained by the application of parameter estimation methods, viz. Classical Least Squares ;CLS', Inverse Least Squares ;ILS' and Kalman Filter ;KF' algorithms. These methods were used to separate strongly overlapping electrochemical peaks produced by binary, ternary an... | 18,967,246 |
Microcoated wire sensors for the determination of anticancer drugs cyclophosphamide and ifosphamide in the presence of their degradates. | The construction and electrochemical response characteristics of poly (vinyl chloride) and poly (vinyl chloride) carboxylate membrane sensors for the determination of cyclophosphamide and ifosphamide are described. Based on the formation of an ion-pair complex between the drug cation and sodium tetraphenylborate, two p... | 18,967,269 |
Screen-printed voltammetric sensor for TNT. | Screen-printed carbon electrodes have been developed as disposable voltammetric sensors for 2,4,6-trinitrotoluene (TNT). Thick-film electrodes based on various conventional and modified inks have been compared for this task. The operation is based on placing the selected thick-film carbon sensor in the non-deaerated/qu... | 18,967,270 |
Quantitative separation of zinc traces from cadmium matrices by solid-phase extraction with polyurethane foam. | A system for separation of zinc traces from large amounts of cadmium is proposed in this paper. It is based on the solid-phase extraction of the zinc in the form of thiocyanate complexes by the polyurethane foam. The following parameters were studied: effect of pH and of the thiocyanate concentration on the zinc extrac... | 18,967,283 |
Glutathione oxidase-like activity of glass beads, silica gel and anion-exchange resin modified with cobalt(III)-tetrakis(4-carboxyphenyl)porphine. | Silica gel and glass beads were modified by using acid chloride of metal-tetrakis(4-carboxyphenyl)porphine (M-TCPP) through a peptide bond, and an anion-exchange resin with M-TCPP by ion-exchange reaction and physical adsorption. The carriers modified with Co(3+)-TCPP proved to accelerate the redox reaction which is ca... | 18,967,291 |
Transport and separation of Ag(+) and Zn(2+) by donnan dialysis through a monovalent cation selective membrane. | Donnan Dialysis of Ag(+) and Zn(2+) was investigated through a cation exchange membrane (CMS Neosepta) when a proton concentration difference was maintained between the two sides of the membrane. Developed for the production of brine from sea water, CMS Neosepta showed a higher permeability to monovalent than to bivale... | 18,967,293 |
pH-Metric determination of acid numbers in petroleum oils without titration. | A new pH-metric method without titration has been developed for determination of acid numbers lower than 0.1 mg (KOH) g(-1) (oil) in petroleum oils such as White, Transformer and Basic oils. The method is based on rapid and complete extraction of acids from an oil test portion into the novel reagent and measurement of ... | 18,967,302 |
Simultaneous determination of copper, cadmium and nickel by ratio derivative polarography. | Ternary mixtures of metals can be resolved by using the ratio derivative polarography without the need for any pre-separation step. The method is based on the simultaneous use of the first derivative of ratios of polarograms and measurements of zero-crossing potentials. The polarogram of the mixture is obtained and the... | 18,967,312 |
Rapid detection of Escherichia coliform with a bulk acoustic wave sensor based on the gelation of Tachypleus amebocyte lysate. | A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscos... | 18,967,327 |
Kinetic determination of trace cobalt(II) by visual autocatalytic indication. | A highly sensitive and simple visual autocatalytic method has been developed for the determination of trace cobalt. The cobalt ion released by the oxidative decomposition of inert bis[2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropyl-amino-phenolato] cobaltate (Co(III)-5-Br-PAPS) with peroxomonosulfate acts as a catal... | 18,967,335 |
Flow-injection catalytic spectrophotometric determination of nitrite using the redox reaction between naphthol green B and potassium bromate. | A flow injection catalytic spectrophotometric method is proposed for the determination of nitrite based on its catalytic effect on the redox reaction between naphthol green B and potassium bromate in phosphoric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of naph... | 18,967,351 |
Analysis of binary mixtures of flufenamic, meclofenamic and mefenamic acids by derivative synchronous fluorescence spectrometry. | Second-derivative synchronous fluorescence spectrometry was used to develop a simple, rapid and sensitive spectrofluorimetric method for the determination of binary mixtures of the nonsteroidal antiinflammatory drugs flufenamic (FFA), meclofenamic (MCFA) and mefenamic (MFA) acids in serum and pharmaceutical formulation... | 18,967,356 |
The effect of polymeric supports and methods of immobilization on the performance of an optical copper(II)-sensitive membrane based on the colourimetric reagent Zincon. | A comparative study on the effect of different immobilization methods and matrix materials on the performance of copper(II)-sensitive membrane layers is presented. The indicator dye Zincon was immobilized in hydrophilic and hydrophobic polymers by various methods including: (a) physical entrapment of the Zincon-tetraoc... | 18,967,361 |
Electrochemical detection of lectin using a galactosamine labeled with daunomycin. | To detect a lectin from soybean, an electrochemical procedure was developed by the use of a labeling of galactosamine. Because the lectin has binding sites to galactosamine, galactosamine labeled with daunomycin having electroactivity was prepared. When labeled galactosamine (LG) combines with lectin, the part of dauno... | 18,967,370 |
Influence of interfering dissolved organic matter on the determination of hydrogen peroxide by a colorimetric method based on the peroxidase catalyzed oxidation of N,N-diethyl-p-phenylenediamine. | The influence of dissolved organic matter (DOM), such as humic acid (HA) and hydroxybenzoic acids, on the determination of H(2)O(2) via a colorimetric method using N,N-diethyl-p-phenylenediamine (DPD) was examined. The influence of DOM on absorbance decay at 551 nm, which represents the wavelength for maximum absorptio... | 18,967,396 |
Decomposition mechanism of an artemisinin-type compound via hemin-electrocatalysis. | The interaction between a typical derivative of artemisinin and hemin was investigated by electrochemical and spectroelectrochemical methods. This derivative can be reduced via hemin-catalysis at the glassy carbon electrode, the cathodic overpotential is decreased by ca. 650 mV. A HPLC method for separating the product... | 18,967,453 |
Determination of low molecular weight organic acids in soil solution by HPLC. | An HPLC method employing an ion exclusion column was developed for the determination of low molecular weight organic acids in soil solution. The method includes extensive sample pretreatment using ultrafiltration and cation exchange. The method showed linear calibration graphs (r>0.99) and the limits of detection in... | 18,967,456 |
Modification of iodometric determination of total and reactive sulfide in environmental samples. | In iodometric determination of sulfide two reactions are taking place when alkaline solution is added to HCl acid-iodine. The main oxidation reaction (1), H(2)S+I(2)=2HI+S; and side reaction of sulfide (2), S(-2)+4I(2)+8OH(-)=SO(4)(2-)+8I(-)+4H(2)O. Preference of reaction (2) over (1) is dependent on pH increasing to &... | 18,967,472 |
A novel biosensor for specific determination of hydrogen peroxide: catalase enzyme electrode based on dissolved oxygen probe. | A biosensor for the specific determination of hydrogen peroxide was developed using catalase (EC 1.11.1.6) in combination with a dissolved oxygen probe. Catalase was immobilized with gelatin by means of glutaraldehyde and fixed on a pretreated teflon membrane served as enzyme electrode. The electrode response was maxim... | 18,967,474 |
Quantitative measurements of ammonium, hydrogenophosphate and Cu(II) by diffuse reflectance spectrometry. | Diffuse reflectance spectrometry is shown to be useful for the quantitative determination of small amounts of pollutants. The relation between sample concentration and reflectance is described by the Kubelka-Munk equation. The experiments were performed with a laboratory constructed diode array spectrophotometer. We ca... | 18,967,477 |
Determination of methylamphetamine and related compounds in human urine by high performance liquid chromatography/electrospray/mass spectrometry. | A study of liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) for the determination of methylamphetamine and related compounds (amphetamine, ephedrine, phenylpropanolamine) in human urine was undertaken. We assessed the effect of collision induced dissociation (CID) spectra generated by varying exit voltag... | 18,967,481 |
Evaluation of luminol-H(2)O(2)-KIO(4) chemiluminescence system and its application to hydrogen peroxide, glucose and ascorbic acid assays. | A novel chemiluminescence (CL) system was evaluated for the determination of hydrogen peroxide, glucose and ascorbic acid based on hydrogen peroxide, which has a catalytic-cooxidative effect on the oxidation of luminol by KIO(4). Hydrogen peroxide can be directly determined by luminol-KIO(4)-H(2)O(2) CL system. The det... | 18,967,485 |
Determination of rare earth impurities in high purity gadolinium oxide by inductively coupled plasma mass spectrometry after 2-ethylhexylhydrogen-ethylhexy phosphonate extraction chromatographic separation. | A method was developed for the determination of rare earth impurities in high purity Gd(2)O(3) by inductively coupled plasma mass spectrometry (ICP-MS). The matrix suppression effect of Gd(2)O(3) on signals of rare earth impurities was compensated for by Re internal standardization. The spectra overlap interferences fr... | 18,967,492 |
Determination of sulfate ion by potentiometric back-titration using sodium tetrakis (4-fluorophenyl) borate as a titrant and a titrant-sensitive electrode. | A potentiometric back-titration method for the determination of sulfate ions using a plasticized poly(vinyl chloride) membrane electrode sensitive to a titrant is described. The method is based on ion association between the excess of 2-aminoperimidinium added to the sulfate ion in the sample and sodium tetrakis (4-flu... | 18,967,507 |
Raman spectroscopic determination of inosine nucleoside in nucleotides. | Raman spectroscopy has been applied to the analytical determination of inosine nucleoside in nucleotides. Spectral characteristics of aqueous solutions of lithium, potassium and magnesium salts of inosine 5'-monophosphoric acid are described. Two characteristic bands located at 1553 and 1593 cm(-1) whose frequencies ar... | 18,967,520 |
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