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We describe in this paper an electrochemical and spectrophotometric study of the behavior of an electropolymerized nickel porphyrin film as a sensor for the determination of nitric oxide (NO) in aqueous solution. Our results show that the anodic oxidation of NO at the modified electrode may not be the result of a catalytic effect induced by the porphyrinic complex. However, the current (measured...
A continuous monitoring system for vinyl chloride gas in air has been developed using an HCl monitoring tape and pyrolyzer consisting of a heater around a quartz tube. It is based on the color change of the tape by reaction with HCl gas produced by decomposition of vinyl chloride gas in the heated quartz tube. The conversion efficiency of vinyl chloride into HCl depends on the temperature of the...
a polysterenedivinylbenzene-based macroreticular resin was functionalised with bis-(N,N -salicylidene)1,3-propane-diamine ligands and its analytical properties have been investigated. The pH dependence of metal resin chelation has been determined for Cu(II), Ni(II), Co(II), Zn(II), Fe(II), Mn(II), Pb(II), Cd(II) and Cr(III). Trace amounts of these metal ions were quantitatively retained on the...
We compared two extraction methods for use in GC-ECD determination of polychlorinated bi- and terphenyl contaminants (PCBs and PCTs respectively) in mussels (Mytilus galloprovincialis). Mussels spiked with standard PCB and PCT mixtures Aroclor 1260 and Aroclor 5460 were extracted with cold acetonitrile, or with 1:1 n-hexane/dichloromethane in a Soxhlet extractor, which gave the better mean recoveries...
Ruthenium and osmium (up to 20 μg Ru(Os) ml -1 ) can be determined in chloride solutions directly after absorption of RuO 4 and OsO 4 in hydrochloric acid. In 9 M HCl, RuO 4 and OsO 4 are quantitatively converted into RuCl 2-6 (λ max = 480.0 nm, ε = 4.8 10 3 1 mol -1 cm -1 ) and OsCl...
Acid-base properties of molecular weight fractionated humic acids (HAs) were investigated by the acid-base potentiometric titration. The acidic group contents (C At ) and the average values of apparent pK (pK app ) were evaluated by applying a modified Henderson-Hasselbalch equation to the experimental titration curves. The average values of pK app ...
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 bottles of each coal. Individual data are presented and some problems (calibration,...
The immobilization and electrical connection of a viologen-accepting pyridine nucleotide oxidoreductase (VAPOR) on an electrode surface by coadsorption with an amphiphilic pyrrole viologen and electropolymerization of this pyrrole monomer are described. The immobilized VAPOR catalyzes the reduction of NAD(P) + to NAD(P)H by the viologen redox couple (V 2++ ). The sensitivity...
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 value decreases from 9.5 to 8.2.According to polarographic and spectrophotometric...
A room temperature photochemically-induced fluorescence (RTPF) method is proposed for the quantitative analysis of seven widely-used chlorophenoxyacid herbicides. The influence of organic solvent, pH (in aqueous solutions), methanol percentage, and UV irradiation time on the excitation and emission wavelengths and fluorescence intensity was investigated. It was found that the largest fluorescence...
A sensitive inductively-coupled plasma atomic emission spectrometric sequential method for the determination of trace heavy metals (cadmium, cobalt, copper and nickel) in biological samples after extraction of the metals into isobutyl methyl ketone (IBMK) containing 1,5-bis-(di-2-pyridylmethylene)thiocarbonohydrazide (DPTH) is described. A systematic study was made to determine the optimum conditions...
Multivariate analysis in combination with pattern recognition procedures has been applied to samples of green and black tea. Discriminant analysis has been used for classification purposes. Aqueous extract, polyphenols, amino acids, caffeine, theobromine and theophylline were used as chemical descriptors.
A simplified fraction of the Oural crude oil (aliphatic and aromatic hydrocarbons) was incubated in the presence of an hydrocarbonoclastic bacterial community isolated from a marine sediment highly contaminated by petroleum residue. The biodegradation has been carried out under aerobic conditions for 5 weeks and followed by FTIR, UV synchronous luminescence and GC/FID. Disappearance of the n-alkanes...
A study was carried out with a continuous hydride generator coupled to an atomic emission spectrometer with inductively-coupled plasma to determine whether hydrides of As, Bi, Pb, Sb, Sn and Se and mercury vapor could be generated in methanol solutions of their dithiocarbamate complexes. It was found that (with the exception of Pb) hydride generation with sufficient efficiency for simultaneous multi-element...
The combination of liquid chromatography with mass spectrometry (LC-MS) allows non-volatile and thermally sensitive compounds to be handled. The key feature, regarding LC flowrate and MS vacuum requirements, is the LC-MS interface system. Atmospheric pressure chemical ionization (APcI) is a sensitive and widely applicable method which gives primarily molecular weight information with the ability...
A kinetic-dual standard additions method for simultaneous determination of interfering binary mixtures is proposed, and the principles discussed. The deviations of the absorbance from additivity in kinetic systems, caused by a synergistic effect between the two catalysts, are effectively compensated with the defined synergistic catalytic coefficient. The hydrogen peroxide-iodide kinetic reaction...
The phosphine oxide Cyanex 921 (tri-n-octylphosphine oxide) was found to be a very efficient extractant for gold from aurocyanide aqueous solutions. A system comprising a microcolumn packed with this new reagent was developed for the separation and enrichment of gold. Because of the high selectivity of the developed system it is possible to analyze gold in the presence of an excess of other metals...
A new kind of poly(N-aminoethyl)acrylamide chelating fiber was synthesized from nitrilon (an acrylonitrile-based synthetic fiber) and used for the concentration and separation of traces of noble metal ions from solution. The results showed that 16-80 ng ml -1 of Au(III), Pt(IV), Pd(IV), Ir(IV), Ru(III) and Rh(III) can be quantitatively concentrated by the fiber up to a flow rate of 20...
A spectrofluorimetric method for the simultaneous determination of dysprosium, europium, gadolinium and terbium in ternary and quaternary mixtures by the use of pyridine-2,6-dicarboxylic acid as a chelating agent was developed. The influence of chemical variables affecting the analytical reaction was evaluated. A partial least-squares procedure and PC Quant software were used to assess data obtained...
The advantages of combined gas chromatography-mass spectrometry and direct deposition gas chromatography-Fourier transform infrared spectrometry at the same level of sensitivity are demonstrated using an apolar capillary column. This technique was applied to allelochemicals present in minute concentrations. The identification of volatiles in green leaves and an alkaloid is described.
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