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A chemiluminescence flow injection system is described for the determination of nitrate, involving use of a laboratory-built flow-through photochemical reactor. Optimum analytical conditions were established. The linear range for nitrate is 7 10 -8 -1 10 -4 M. The sampling frequency is 60 samples per hour. The relative standard deviation for 1 10 -7 ...
A high performance liquid chromatographic method for the determination of ultra trace amount of aluminium in natural waters has been developed using lumogallion as a precolumn reagent for fluorimetric detection. The highly fluorescent Al-lumogallion chelate (λ ex 500 nm, λ em 574 nm) was separated on a LiChrosorb RP 18 column with an eluent containing 3:7 acetonitrile/0...
Electropolymerized m-phenylenediamine was used as an active coating for immobilizing urease and lectin on a gold-plated thickness-shear-mode (TSM) crystal. To enhance effectiveness of immobilization, a bilayer polymer film composed of polyaniline and poly-m-phenylenediamine was proposed. Compared with single poly-m-phenylenediamine film, the bilayer polymer film gave better results in terms of immobilizing...
A rapid, highly selective and simple method has been developed for the quantitative determination of pyro-, tri- and orthophosphates. The method is based on the formation of a solid complex of bis(ethylenediamine)cobalt(III) species with pyrophosphate at pH 4.2-4.3, with triphosphate at pH 2.0-2.1 and with orthophosphate at pH 8.2-8.6. The proposed method for pyro- and triphosphates differs from...
A novel oxygen (O 2 ) and/or carbon dioxide (CO 2 )-sensitive transducer for the measurement of both gaseous O 2 and CO 2 over the concentration ranges of O 2 , 0-100% and CO 2 , 0-10% has been described employing a solution of 10.6 μM fluorescein (FL) and 190 μM potassium hydroxide in a solvent mixtures of 1:1 (v/v) N,N -diethylaniline (DEA) and N,N-dimethylformamide...
A method was developed for the ultra-trace determination of tin by in situ preconcentration in a graphite tube using a flow injection hydride generation technique with on-line ion-exchange separation. The sample was prepared in 2M hydrochloric acid before being passed through an incorporated micro-column packed with a strongly basic anion-exchanger D-201. The tin was retained as its chlorostannate...
Organic vapours were measured by an array of piezoelectric crystal detectors. Quartz crystals were coated by different GC stationary phases. Four coated crystals were placed in an array and pattern recognition was used for identification of the compounds including acetone, benzene, chloroform and pentane. A computer program was developed for the measurement of the frequency changes and data processing...
Trace levels of manganese can be determined by voltammetry after controlled adsorptive accumulation of the manganese-2-(5 -bromo-2 -pyridylazo)-5-diethylaminophenol (5-Br-PADAP) complex on a hanging mercury drop electrode. Optimal conditions include an ammonia buffer solution (pH 8.8) containing 1 10 -5 M 5-Br-PADAP and an accumulation potential of -1.20 V. The technique offers...
Soil collected from a disused cattle dip in northern New South Wales was studied with the aim of developing an inexpensive, yet effective method for quantitative determination of arsenic(III), arsenic(V) and total organic arsenic in a contaminated soil. Hydrochloric acid extractions were used as a method for removal of the arsenic from the soil in a form suitable for speciation. It was found that...
A complexation chemistry model is applied to chelating ion-exchange systems and a method is presented for the determination of equilibrium constants for metal ion chelates with these resins. Protonation constants for the iminodiacetic based chelating resin Dowex A-1 were determined from potentiometric pH-data. Equilibrium constants were determined for 1:1 beryllium, magnesium, calcium, strontium...
The first stability constants (log β 1 ) of the copper(II) complex of glycine in water and in 13 water + alcohol (isopropanol, tert-butanol, 1,2-propylene glycol and glycerol) solvents have been determined at 25°C and an ionic strength of 0.10, from pH and pCu measurements of cells containing copper(II) ion selective electrode. It has been shown that as the proportion of the alcohol increases,...
The adequation of the current theories for calculating activity coefficients has been studied for a series of ionic equilibria in analytical chemistry: the water ionic product as well as two reactions of complex formation and oxidation-reduction. In all the cases, the specific interaction theory (SIT) has proved to be adequate and simple to apply in a restricted interval (0.5-3 M), whereas Pitzer's...
When Pd and EDTA ammonium salt are used as a common matrix modifier, the establishment of a common furnace programme for the determinations of indium, silver and thallium would greatly simplify routine analysis. The continuous determination of indium, silver and thallium by the analyses on the basis of characteristic mass and the graphite furnace with the V-shaped boat is described. The possibility...
Ultrasmall-volume measurements of oxidizable compounds have been accomplished by coupling a capillary flow injection system with amperometric detection. Remarkably low (femtomole) mass detection limits result from the combination of nanoliter sample volume and the inherent sensitivity of the wall-jet detector. A substantial economy of reagent consumption and disposal accrues from the operation of...
Immobilized enzymes were used as column reactors in a high-performance liquid chromatographic system for the specific detection of N-acetyl branched-chain amino acids (AcBCAs) such asN -acetyl-l-valine (AcVal), N-acetyl-l-leucine (AcLeu) and N-acetyl-l-isoleucine (AcIle). Aminoacylase and leucine dehydrogenase were immobilized onto poly(vinyl alcohol) beads. The AcBCAs were separated as three peaks...
The methods for optimal acidity of complexes M x L y (OH) m H n based on direct iteration or solution of polynomials are described and discussed. Then, by a direct straightforward method of computation (that does not require any iteration) the complexes M x L(OH) m H n and ML y (OH) m H n are treated (where 1 x 3...
Disposable amperometric sensors for hydrazines have been fabricated by a judicious tailoring of the surface of screen-printed electrodes. Strong electrocatalytic action towards the oxidation of hydrazines is achieved by incorporating cobalt phthalocyanine within the carbon inks or by covering the printed surface with a mixed valent ruthenium cyanide coating. The electrocatalytic behavior, sensor...
Iron, cobalt and copper form coloured water soluble anionic complexes with disodium 1-nitroso-2-naphthol-3-6-disulphonate (nitroso R-salt). The anionic complex is retained quantitatively as a water insoluble neutral ion associated complex (M-nitroso R-TDBA) on tetradecyldimethylbenzylammonium iodide on naphthalene (TDBA + I - -naphthalene) packed column in the pH range of: Fe(III):...
A flow injection configuration for the fluorimetric determination of thiourea is proposed. The procedure is based on the rapid oxidation of thiourea by thallium(III) with concomitant formation of fluorescent thallium(I). Linear calibration graphs were obtained between 5 10 -7 and 1 10 -5 M, with a sampling rate of 90 samples/hr. The usefulness of the method was tested...
A spectrophotometric method was developed for determination of concentration-based pH values from 0 to 2 with Malachite Green indicator. A quadratic model equation was based on the ratio of the absorbances of the peak at 618 nm and the isosbestic point at 518 nm. Normalization to the isosbestic point was used to stabilize the response because the color faded; the useful time interval was within 5...
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