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A simple and convenient method has been developed for the speciation of chromium(III) and chromium(VI) in aqueous solutions using a sodium dodecyl sulphate coated alumina micro-column (1.5 cm 5 mm i.d.) and graphite furnace-atomic absorption spectrometry (GF-AAS). Under the optimized conditions (pH 0.6, adjusted with hydrochloric acid; flow rate, 1 ml min -1 ) chromium(VI) is retained...
A systematic study of the fluorescence of complexes of some flavone derivatives with organotin compounds in hexane and in an aqueous micellar medium on Triton X-100 is reported. Some relationships between fluorescence intensity and the structure of the fluorogenic reagent or that of the organotin compound can be deduced, and the most suitable reagent for each organotin species can be chosen on the...
An automatic method for the estimation of Michaelis-Menten and inhibitor constants in biochemical systems was developed using an unsegmented open-closed flow manifold, and the Lineweaver-Burk and Dixon plot methods. The methods were applied to both the determination of K m of the enzymatic reaction catalyzed by bovine alkaline phosphatase using 4-methylumbelliferone phosphate as substrate,...
A spectrophotometric study is presented on the first ionization equilibrium of a class of substituted sulfonephthaleins, whose second ionization was the subject of the first part of this work. The present study was more difficult than the previous in that highly acid media and acidity functions had to be used. Nevertheless the results were of sufficient accuracy to allow the dual substituent analysis...
Solid-phase spectrophotometry has been applied to analysis for trace amounts of vanadium. Vanadium was sorbed in a styrene-divinylbenzene-type anion-exchanger Dowex 1-X8 as a vanadium-4-(2-pyridylazo)resorcinol complex. Resin phase absorbances at 562 and 800 nm were measured directly which allowed the determination of vanadium in the range of 0.1-2.4 ng/ml with a RSD of 1.5%. The method has been...
A highly sensitive photometric flow-injection method is described for the determination of iron(II, III) based on the catalytic action on the oxidative coupling of N-phenyl-p-phenylenediamine with m-phenylenediamine in the presence of hydrogen peroxide. The sensitivity of the method was enhanced by the addition of Tween 80 as a surfactant. The dynamic range was 0.5-30 ng/ml of iron(II, III) with...
A new method has been developed for the determination of antimony, arsenic, bismuth, selenium, tellurium and tin by hydride generation-atomic absorption spectrometry in an electrically heated quartz tube furnace under sub-atmospheric pressure. The hydride generator, operating at a pressure lower than atmospheric, is used to generate and collect the hydrides of these elements. A certain volume (at...
A flow injection on-line preconcentration technique, combined with graphite furnace atomic absorption spectrometry for the determination of gold in ore samples has been presented. An α-amino pyridine resin (AP) was loaded onto a microcolumn as the preconcentration reagent and a solution of 90% acetone-5% HCl-5% H 2 O was used for the gold elution. The Scaled Simplex Method was employed to...
A simple and sensitive photometric method for the trace determination of 1-naphthylamine has been worked out. The method is based on the coupling reaction of the determinand in acidic medium with diazotized sulfisomidine, to form a purplish violet water-soluble mono azo dye that shows maximum absorption at 540 nm with a molar absorptivity of 4.47 10 4 l mol -1 cm - ...
Dopamine tissue sensors were prepared using biofilms containing pretreated tissue powder of potato, banana, mushroom and apple. These sensors showed good stability, reproducibility and service life span of more than 200 days involving 300 to 500 measurements. Overlaying the sensors with a Nafion coating considerably improved the sensor selectivity for dopamine by effectively precluding neutral and...
The cationic surfactant hexadecyltrimethylammonium bromide enhances the fluorescence intensity of both molybdenum and tungsten complexes obtained with Alizarin Red S. This characteristic has been used for a sensitive simultaneous spectrofluorimetric determination of both ions over the range 32-4000 ng/ml and 49-2500 ng/ml for Mo and W, respectively. Good selectivity is achieved applying the well...
A new functional resin with a long functional side chain was synthesized by modification of aminated macroporous poly(vinyl chloride) resin with cyanoethylene and ethylenediamine. Traces of Au(III), Pt(IV) and Pd(II) in aqueous solution were quantitatively adsorbed in the acidity range of pH 4 and C H+ 3 M. The rate of equilibration is high; Cu 2+ , Fe 3+ ...
A sensitive method for the determination of strontium has been developed. In this work strontium was determined by flame atomic absorption spectrometry using a continuous copreconcentration dissolution procedure based on the formation of lead sulfate followed by elution with hot EDTA solution. Manifold parameters and chemical conditions are described in detail. A concentration factor of up to 61...
A direct spectrophotometric method for the determination of aluminium with morin has been developed. Morin reacts in slightly acidic 50% ethanolic media (0.0001-0.0015 M H 2 SO 4 ) with Al to give a deep-yellow chelate which has an absorption maximum at 421 nm. The average molar absorptivity and Sandell's sensitivity were found to be 5.3 10 3 l mol -1 cm ...
Lead(II) reacts with pyridine-2-acetaldehyde salicyloylhydrazone (PASH) in the pH range 8.6-9.3 to form a yellow-green, 1:2 chelate which can be extracted into chloroform. Beer's law is obeyed in the concentration range 1.5-6.2 μg ml -1 of lead(II). The molar absorptivity of the extracted species is 1.93 10 4 l mol -1 cm -1 at 380 nm. The proposed...
The determination of salicylic acid was carried out by reaction of the drug with copper carbonate entrapped in a polymeric material in a solid-phase reactor; the released cupric ions were monitored by flame atomic absorption at 324.8 nm. The calibration graph is linear over the range 4.0-75 μg ml -1 of salicylic acid, with a relative standard deviation of less than 1.5% and a sample...
A new fusion agent is proposed for the analysis of cement and cement raw meal using AAS. In the described method, 0.8 g of the fusion agent, consisting of equal portions of oxalic acid, lithium carbonate and lithium tetraborate, was mixed with 0.2 g of the sample, and the mixture was fused for 10 min at 925°C in a platinum crucilbe. The fusion cake was dissolved with dilute hydrochloric acid (1...
A multivariate approach to the solution of problems often encountered in the spectrofluorometry of natural samples, utilising information from whole spectra is presented. (a) Piecewise direct standardisation is implemented and employed to transfer emission spectra measured with two different xenon lamps of different ages as if the spectra were measured with the same lamp. (b) It has been shown using...
The combination of flow injection analysis with membrane introduction mass spectrometry for analysis of volatile organic compounds (VOCs) in seawater is examined and is compared to measurements made in water. Membrane introduction mass spectrometry is performed using a benchtop ion trap mass spectrometer, and characterization of various aspects of the flow injection and ion trap combination for the...
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