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A sequential extraction procedure for separating and determining Be(0), soluble Be(II) inorganic compounds, BeO and beryllium silicates in samples such as particulate matter of emissions and working areas, has been developed. The proposed procedure has been tested on synthetic samples prepared with the inorganic beryllium compounds, in the presence of atmospherical particulate matter sampled in a...
An extraction procedure for the spectrophotometric determination of sodium or potassium involving a 1:1:1 metal ion: crown ether: sulfonephthalein dye monoanion ion associate has been described in the literature. In a recent paper from this laboratory the total dye content of the organic phase resulting from partitioning bromocresol green (HBCG) alone between water and benzene was determined from...
Equilibrium studies based on pH-potentiometric and spectrophotometric measurements as well as some theoretical simulations are reported for the complexes of Mo(VI) with a dihydroxamate type siderophore analogue, the piperazine-1,4-bis-(N-methyl-acetohydroxamic acid) (PIPDMAHA). It has been found that the complexation process starts below pH 2 and that PIPDMAHA forms more stable O,O-hydroxamate bis-chelated...
Different sample pre-treatments for seafood products have been compared with determine trace elements (As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Se and Zn) by flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). Classic pre-treatments as microwave assisted-acid digestion and the slurry sampling technique were compared with new procedures such as microwave...
The suitability of 1-nitroso-2-naphthol (NN) as a complexing agent for on-line preconcentration of cobalt using C 18 microcolumn with FI-FAAS system has been tested. Various parameters affecting the complex formation and its elution were optimized. Reagent solution (2.5x10 -3 mol l -1 ) and aqueous sample solution acidified with 0.1% (v/v) nitric acid were on-line...
The surfactants of hexadecyl-pyridinium chloride and dodecylbenzenesulfonic acid are recovered from the aqueous systems by solvent sublation into organic solvent. The mathematical model of surfactants by solvent sublation is built and many parameters are analyzed in details. The simulation of the mathematical and experimental data is completed with perfect results.
Mesostructured tin oxide with high specific surface area was synthesized using cationic surfactant (cetyltrimethylammonium bromide, CTAB: CH 3 (CH 2 ) 15 N + (CH 3 ) 3 Br - ) as the organic template and hydrous tin chloride (SnCl 4 .5H 2 O) and NH 4 OH as the inorganic precursors under acidic conditions at ambient...
A new chemiluminescence (CL) method is proposed for the determination of chlorpromazine hydrochloride, a drug often used to treat the psychiatric patients suffering from clinical depression. The method is based on the reaction between studied drug and Ce(IV) in a nitric acid medium and measurement of the CL intensity produced by rhodamine 6G used as a sensitizer. In the optimum conditions, CL intensities...
Polyurethane resin derived from castor oil was used to prepare a graphite composite intented to be applied in voltammetry. The best graphite/resin content in the composite was evaluated using cyclic voltammetry. The useful potential window was investigated in different electrolytes with pH ranging from 1 to 13, with good results in relation to the glassy carbon electrode. Response of this new electrode...
Thermal lensing is used for monitoring the course of unstirred Belousov-Zhabotinsky reaction (a bromate oscillator) based on malonic acid as an organic substrate in 1.5 M sulfuric acid with a mixture of free Fe(II) and its chelate with 1,10-phenanthroline as a catalyst and a photometric indicator of the reaction process. The dependences of the oscillation period and oscillation lifetime on the component...
Protonation constants of arsenic acid were determined at different ionic strengths in NaClO 4 (0.1, 0.5, 1.0, 3.0 mol dm -3 ), NaCl (0.5 and 1.0 mol dm -3 ) and KCl (0.5, 1.0 and 3.0 mol dm -3 ) ionic media by means of a potentiometric study. The distribution of arsenate species was defined depending on two important variables in natural environments:...
The property of dopamine in acid-alkaline medium was studied by spectrofluorimetry and spectrophotometry. Effects of organic solvents on dopamine fluorescence spectra were examined and the reason was discussed. Among the organic solvents tested, methanol was selected as sensitizing reagent. A fluorescence quenching reaction took place in basic medium. Mechanism of fluorescence quenching was discussed...
A novel method for the determination of peroxynitrite using rhodamine B hydrazide as a fluorogenic probe is described. The method is based on the oxidation of rhodamine B hydrazide, a colorless, non-fluorescent substance, by peroxynitrite to give rhodamine B-like fluorescence emission. The fluorescence increase is linearly related to the concentration of peroxynitrite in the range of 7.5x10 -...
Unsymmetrical benzoN 4 nickel(II) macrocyclic complexes have been explored as an ionophore for preparing PVC-based membrane electrodes selective to SCN - . The resulting electrode exhibited the best working concentration range (1.4x10 -7 -0.1 M) with a Nernstian slope of (-59.7+/-0.9 mV per decade) in the wide pH range of 3.5-10.5. The proposed electrode has a very fast...
A new design of a continuous flow system applied to the simultaneous determination of the concentration of zinc(II), cadmium(II), lead(II), copper(II), nickel(II), cobalt(II) and chromium(VI) in river water is described. A flow cell made in the laboratory, which has been patented, based on a 'wall-jet' configuration with a three-electrode system is described. Optimum conditions for the determination...
A rapid and sensitive time-based flow injection (FI) method for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS), using polytetrafluoroethylene (PTFE) turnings as packing material in a micro-column, has been developed. The sample was mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the non-charged Pb(II)-PDC complex was absorbed quantitatively...
A solution of a Zn-complex of recombinant mouse MT-1 isoform (Zn 7 -MT-1) was prepared and titrated with Cd 2+ ions. A method based on the coupling of capillary zone electrophoresis (CZE) with electrospray MS detection was developed for the analysis of the stoichiometry of the species formed during the titration. The method offered the possibility of the on-line removal of up...
The stability constants for copper(I) chelate with 2,9-dimethyl-1,10-phenanthroline are determined by thermal lensing, and the advantages over spectrophotometric determination of stability constants are shown. Changes in the photometric reaction when moving from the microgram to the nanogram level of reactants are discussed. The conditions for the thermal-lens determination of copper are optimized...
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