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101.
The basic principles of Flow Injection Analysis are outlined. The parameters governing the dispersion of the injected sample zone in the system are discussed, and it is demonstrated how these parameters can be manipulated in order to suit the requirements of an individual analytical procedure. A number of examples illustrating the practical application of f.i.a. are described, comprising the use of automated, stopped-flow, merging-zones, extraction techniques as well as f.i.a. scanning and methods based on intermittent pumping. Updated lists on f.i.a. procedures published and species that can be determined by f.i.a. are included. 相似文献
102.
The reactions between ammonium fluoride, hydrazinium(1+) fluoride, hydrazinium(2+) fluoride and XeF2 or XeF6 were studied. It was found that Xe, HF, N2 were formed in these reactions. Interestingly enough, beside of these gases nitrogen fluorides in different quantities were formed also. The courses and the products of the above reactions are compared with analogous reactions with KrF2. 相似文献
103.
The tetranuclear Cu4OBrnCl(6-n)L4 complexes, where L = 3-methylpyridine (3-Mepy), 4-methylpyridine (4-Mepy) and n=0–6 with trigonal bipyramidal coordination of copper(II) were prepared and their infrared and electronic absorption spectra
as well as cyclic voltammograms in nitromethane solutions were measured. The polyhedra in Cu4OBrnCl(6−n) (3-Mepy)4 molecules are less distorted comparing with those of 4-Mepy analogues as indicated by infrared Cu4O absorptions, far infrared Cu—Br, Cu—Cl, and Cu—N absorptions, d—d bands in electronic spectra and potentials, measured by cyclic voltammetry. The 3-Mepy complexes exhibit strong single infrared
Cu4O absorptions, while for related 4-Mepy complexes doubly split Cu4O bands were observed. Two strongly overlapped d—d bands in electronic absorption spectra of the 3-and 4-Mepy complexes in nitromethane were resolved by Gaussian fitting. The
4-Mepy ligand produces slightly stronger ligand field than its 3-Mepy analogue. The maxima of high-energy d—d bands are in a linear correlation with the number of bromide ligands. The correlations for corresponding low-energy bands
are considerably deviated from linearity. The halfwave potentials of the complexes in nitromethane correlate with both the
number of bromides and the data of electronic absorption spectra suggesting that the reducing electron at the electrode process
enters the half-filled d
z
2 orbital of the copper(II) atom. The origin of a difference between the 3-and 4-Mepy complexes in their spectral and electrochemical
properties is also discussed. 相似文献
104.
R. Ramanauskas L. Gudavičiūtė A. Kaliničenko R. Juškėnas 《Journal of Solid State Electrochemistry》2005,9(12):900-908
The influence of pulse plating parameters on the surface morphology, grain size, lattice imperfection and corrosion properties
of Zn–Ni alloy has been studied. The coatings were electrodeposited in an alkaline cyanide-free solution. AFM was applied
for surface morphology examination, XRD measurements were carried out for phase composition and texture analysis, electron
probe microanalysis was used for alloy chemical composition studies, while electrochemical techniques were applied for corrosion
performance evaluation. The pulse plated Zn–Ni coatings appeared to consist of the γ-Zn21Ni5 phase and the composition of the alloy depended on the plating parameters. The grain size, lattice imperfection and homogeneity
of grain distribution were established to be the main factors determining corrosion behaviour of the coating.
Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005 相似文献
105.
Some 804 papers on flow injection analysis published to the end of May 1985 are summarized. Past trends are discussed and new developments are briefly outlined.The paper entitled “Flow Injection Analysis. Part 1. A New Concept of Fast Continuous Flow Analysis” [1], which appeared in August 1975, was the first of some 804 papers [1/2-804] published on flow injection analysis (f.i.a.) during the past ten years. In the present contribution, all these papers are collected to record the status quo of the general method and to reveal the present trends in applications of f.i.a. and in the geographical distribution of the research activities. Important concepts and technological innovations are reviewed and the future development of f.i.a. is briefly outlined. 相似文献
106.
The structures of the stable conformers of N-methyjpropionamide and N-methyliso-butyroamide in CCl4, solution were determined by a combination of IR spectroscopy and NMR spectroscopy with lanthanide shift reagents. N-methyl-propionamide was found to exist in the form of two rotational isomers, 1 and 2, with the ethyl group twisted out of the plane of the amide bond by the angles Ψ = 140 and 20°, respectively. For these two conformers, the enthalpy difference is ΔH = 2.13 ± 0.08 kcal mole?1 and the entropy difference ΔS = 7.81 ± 0.55 cal mole?1 grad?1. N-methylisobutyroamide exists in a single form, with the two C-methyl group positions very close to those found in the two isomers of N-methylpropionamide. 相似文献
107.
By using non-Newtonian viscometry and the static light-scattering method, changes in the structure of particles of latex dispersions of ethyl acrylate-methacrylic acid copolymer during alkalization with ammonium hydroxide were investigated. It was found that in dispersions with an acid content up to 20 wt% the particles only swell; at acid content between 20 and 40 wt% they decompose to smaller units represented by supermolecular aggregates of macromolecules, and only when approximately starting from 40 wt% of acid does the copolymer become molecularly dissolved. This means that even if dispersions with an acid content from c. 20 wt% are clarified by alkalization, no complete dissolution takes place. 相似文献
108.
A. Paulenová P. Rajec M. Ježíková J. Kučera 《Journal of Radioanalytical and Nuclear Chemistry》1996,211(1):145-152
The preconcentration of cadmium from aqueous colloid solution containing 8-hydroxyquinoline as extractant, laurylsulphate natrium as surfactant,n-butanol as co-surfactant was performed using micellar ultrafiltration technique. Filters with different pore size and materials were used to achieve a separation from liquid solutions. The cadmium recoveries depending on different conditions (pH, concentration of surfactant) were determined and the results are explained in the terms of colloidal parameters in the compare with the classical solvent extraction. 相似文献
109.
J. Sereikaité D. Iljasevičiené G. Dienys H. Danilčenko V. Gavrilova 《Applied biochemistry and biotechnology》1993,43(2):153-160
Ascorbate oxidase fromCucurbita sp. was isolated by ammonium sulfate precipitation and DEAE-dextran-silochrome column chromatography. The thermal and pH stabilities
of the purified enzyme were investigated. TheK
M forl-ascorbic acid (1.5 mM) and chlorohydroquinone (0.37 mM) was determined. Substrate specificity of ascorbate oxidase was investigated and compared with those of laccases fromCoriolus hirsutus andCerrena maxima. Ascorbate oxidase was covalently bound to a polymeric membrane and used in an enzyme electrode for ascorbic acid. 相似文献
110.
Žydrė Šaltienė Natalija Jatulienė Mudis Šalkauskas Daiva Brukštienė Asta Ruzgytė Aušra Tarasevičiūtė Julius Kalibatas 《Accreditation and quality assurance》2005,10(8):444-451
The estimation scheme of uncertainty of determination of 1-hydroxypyrene (1-OHP) in urine was developed analysing the main
stages of the analytical procedure: (1) preparation of 1-OHP standards, (2) creation of the calibration curve for the high
performance liquid chromatography (HPLC) analysis method with the evaluation of recovery, (3) measuring procedure of aliquot
of urine, (4) adjusting the pH of aliquot and hydrolysis with enzyme, (5) solid phase extraction, (6) concentration of the
extract, (7) injection of the extract to chromatograph and analysing by the HPLC method, (8) calculation of 1-OHP mass from
the calibration curve, (9) calculation of 1-OHP concentration in urine. The evaluation of the uncertainty is based on quantification
of individual components. Combined uncertainty was calculated using the law of propagation of uncertainties according to the
EURACHEM/CITAC guidelines. Level dependence of the uncertainty arises from the calibration curve.
The limits of detection and quantification were found to be equal to 0.03 and 0.1 ng/mL, respectively. The calculated expanded
level-dependent uncertainty covers 47–27–25% within the concentration range 0.03–0.1–0.4 ng/mL with the materials and equipment
used. These parameters could easily be recalculated according to the proposed scheme if there are some changes in the analysis
procedure. 相似文献