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Papers quoted in Current Contents on project 1-07-219


Quoted papers: 17
Other papers: 56
Total: 73


Title:

Authors:
Gojmerac Ivšić, Astrid (78124)
Tamhina, Biserka (49080)
Journal: Talanta
Number: 12
ISSN: 0039-9140
Volume: 38
Year: 1991
Pages: from 1403 to 1407
Number of references: 12
Language: engleski
Summary: The extraction of niobium(V) from aqueous hydrochloric andsulphuric acid solutions with3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) dissolved inchloroform is described. Niobium(V) can be quantitativelyextracted with HY in the form of two different complexesdepending on the chloride ion concentration in the aqueous phase.At a low chloride concentration or without chloride in theaqueous phase niobium(V) is extracted with HY in the form ofNb(OH)3Y2 and at a high chloride concentration as a mixedNb(OH)3ClY complex. Niobium extraction with HY enables theseparation of niobium(V) and hafnium(IV). The formation of amixed chloro-4-pyridone complex is also applicable for thespectrophotometric determination of niobium in the organic phaseat the maximum absorption at 350 nm.
Keywords: extraction, separation, niobium(V), 4-pyridone derivatives, spectrophotometric determination, niobium(V) complexes

Title:

Authors:
Čižmek, Ankica (45364)
Komunjer, Ljepša
Subotić, Boris (45364)
Široki, Marija (47105)
Rončević, Sanda (164890)
Journal: Zeolites
ISSN: 0144-2449
Volume: 11
Year: 1991
Pages: from 258 to 264
Number of references: 47
Language: engleski
Summary: Kinetics of dissolution of zeolite A in 1 M and 2 M NaOHsolutions, at 338, 343, 348, and 353 K, were studied by (i)measuring the change in concentration of Si and Al in the liquidphase, (ii) determining of the stage of polycondensation ofsilicate anions in the liquid phase, (iii) following the changein particulate characteristics of the suspended zeolite A, and(iv) phase analysis of the solid during the dissolution. Theresults obtained were analyzed and discussed in accordance withknown theories of dissolution, taking into account the chemicaland structural characteristics of zeolites.
Keywords: Zeolite A, dissolution, mechanism, kinetics

Title:

Authors:
Čižmek, Ankica (45364)
Komunjer, Ljepša
Subotić, Boris (45364)
Široki, Marija (47105)
Rončević, Sanda (164890)
Journal: Zeolites
ISSN: 0144-2449
Volume: 11
Year: 1991
Pages: from 810 to 815
Number of references: 11
Language: engleski
Summary: The kinetics of dissolution of zeolite X in 2 M NaOH solutions,at 338, 343, 348, and 353 K, were studied by (i) measuringchanges in the concentrations of Si and Al in the liquid phase,(ii) determining of the stage of polycondensation of silicateanions in the liquid phase, (iii) following the changes in theparticulare characteristics of the suspended zeolite A, and (iv)phase analysis of the solid during the dissolution. The resultsobtained were analyzed and discussed in accordance with the modelof growth and dissolution proposed by Davies and Jones, takinginto account the chemical and structural characteristics ofzeolite X.
Keywords: Zeolite X, dissolution, mechanism, kinetics

Title:

Authors:
Hofbauer, J
Steffan, Ilse
Hoebarth, K
Vujičić, Goran (183371)
Schwetz, H
Reich, G
Zechner, O
Journal: J.Urology
ISSN: 0022-5347
Volume: 145
Year: 1991
Pages: from 93 to 96
Number of references: 23
Language: engleski
Summary: The urinary stone, serum and 24-hour urine concentrations of 14trace elements were determined in urinary stone patients byinductively coupled plasma atomic-emission spectroscopy. The dataobtained for 25 active stone patients and 32 whose last stoneepisode had occured at least 12 months previously were comparedwith those of 25 healthy individuals. Urinary nickel, manganeseand lithium excretion, and serum nickel, manganese and cadmiumconcentrations were statistically significantly lower for activestone patients compared with those with previous stone episodesand healthy individuals. No difference in the concentrations oftrace elements could be found, however, for patients withprevious stone episodes and healthy individuals. Nickel,manganese, lithium and cadmium could be of significance in thepathological mechanism of stone formation, not from mineralogicalor crystallographical viewpoints but for the smooth flow ofenzymatic reactions in biological systems.
Keywords: calculi, urinary calculi, urolithiasis

Title:

Authors:
Steffan, Ilse
Vujičić, Goran (183371)
Journal: Spectrochim.Acta B
ISSN: 0584-8547
Volume: 47
Year: 1992
Pages: from 61 to 70
Number of references: 18
Language: engleski
Summary: Two modifications were applied to a commercial spark ablationsystem. A cyclone spray chamber system was installed between thespark device and the inductively coupled plasma (ICP) torch andas outer gas, a mixture of argon and 10% oxygen, was used at 1200W incident power. The control of the aerosol particle size by thecyclone system leads to an improvement in the reproducibility ofthe method compared to a commercial system and preventsdeposition of material on the torch injector. The modified system was tested for the analysis of nonconductivepowders. The samples were briquetted into pellets with graphiteand wax. The addition of wax (Hoechstwachs C, Hoechst,F.R.G.)enables a better ablation of the material. At the same time themechanical properties of the pellets are improved. The optimumamounts of additives for preparation of the pellets were found tobe 20% graphite and 2.4% wax. The applicability of the method wasdemonstrated using Siemens standard rock materials. For smallamounts of powdered samples a graphite cup method was applied.Values of background equivalent concentrations (BEC) achieved forgeological samples are comparable to the values achievable with aDC arc and even better than the BEC values for ICP solutionanalysis. For the elements determined (Sr, Co, Nb,Zn, Cu, Pb, Zr,Ni, Mn, P, Mg, and Cr) the detection limits range from 0.2 to 9(mikro)g/g.
Keywords: ICP-AES, nonconductive materials, spark ablation

Title:

Authors:
Cimerman, Zvjezdana (91635)
Galešić, Nikola (12905)
Bosner, Branka (149946)
Journal: J. Mol. Struct.
ISSN: 0022-2860
Volume: 274
Year: 1992
Pages: from 131 to 144
Number of references: 21
Language: engleski
Summary: The Schiff bases 2-amino-3-salicylideneaminopyridine (1) and2,3-bis(salicylideneamino)-pyridine (bimorphous, 2a and 2b) wereprepared and characterized by X-ray crystallography and by IR andNMR spectrometry. The angle between the benzene and the pyridinering is 51.5(2)o in 1, whereas in 2a the corresponding angles are51.1(4)o in molecule A and 51.8(4)o in molecule B. Molecules of 1are connected in pairs by two centrosymmetric hydrogen bondsN-H...NPy of 3.024(5)Ao. Intermolecular bonding of 1 does not take place in CHCl3solution. No evidence was found in the IR and NMR spectra fortautomeric interconversion of 1 and 2 into the ketoamine or forcyclization of 2 into the cyclic diamine.
Keywords: Schiff bases, salicylaldehyde, 2,3-diaminopyridine, X-ray structure

Title:

Authors:
Alegretti Živčić, Vlasta (29910)
Herak, Marko (15552)
Journal: Croat.Chem.Acta
Number: 4
ISSN: 0011-1643
Volume: 65
Year: 1992
Pages: from 901 to 906
Number of references: 16
Language: engleski
Summary: Monooctyl- -anilinobenzylphosphonic acid was used as extractivereagent for the separation of bismuth(III) and lead(II). Theoptimal pH value for bismuth(III) extraction was 1.75, whereaslead(II) was quantitatively extracted at pH 5. The separationfactor for the two investigated metal ions at pH 1.75 was 140. Onthe basis of extractive experimental data, the stoichiometry ofthe extraction mechanisms was presumed. The described method issimple and rapid and can be proposed for the separation ofbismuth(III) from lead(II).
Keywords: monooctyl-(alfa)-anilinobenzylphosphonic acid, extraction, separation, bismuth(III), lead(II)

Title:

Authors:
Čižmek, Ankica (45364)
Komunjer, Ljepša
Subotić, Boris (45364)
Široki, Marija (47105)
Rončević, Sanda (164890)
Journal: Zeolites
ISSN: 0144-2449
Volume: 12
Year: 1992
Pages: from 190 to 196
Number of references: 13
Language: engleski
Summary: The kinetics of dissolution of synthetic mordenite in 1 M NaOHsolution at 338,343,348, and 353 K were studied by following thechanges in the characteristics of the solid and the liquid phaseduring the dissolution. Various experimental techniques such asICP spectroscopy, FTi.r. spectroscopy, X-ray diffractometry, andparticle-size distribution measurement were used for thispurpose. The results obtained were analyzed and discussed inaccordance with the model of growth and dissolution proposed byDavies and Jones, taking into account the chemical and structuralcharacteristics of synthetic mordenite.
Keywords: Synthetic mordenite, dissolution, mechanism, kinetics

Title:

Authors:
Hus, Mihovil (78363)
Herak, Marko (15552)
Journal: J.Radioanal.Nucl.Chem.
ISSN: 0134-0719
Volume: 171
Year: 1993
Pages: from 407 to 415
Number of references: 11
Language: engleski
Summary: The radioactive tracer method was used to investigate theadsorption of iodide and europium ions from aqueous solution ondried isoelectric precipitates of silver sulfide, silver iodideand silver bromide. The relationship between the amount of iodideions adsorbed on Ag2S and the iodide ion and HNO3 concentrationsin the solution was determined. It was shown that the iodide ionsadsorbed on Ag2S could be desorbed with sulfide ions. Using Ag2S,AgI and AgBr precipitates, a relationship between the europiumion adsorption and Eu(NO3)3, H2S, NaI, NaBr and NaClconcentration in solution was established. The adsorption ofeuropium ions was also assessed in respect to the presence oflanthanum and barium ions. For adsorption measurement iodide andeuropium ions were labeled with their radioactive isotopes andthe amounts adsorbed were determined from the measuredradioactivities of the precipitates after reaching theequilibrium between the solid phase and the solution.
Keywords: radioactive tracer method, adsorption, iodide, europium, precipitation, silver sulfide, silver iodide, silver bromide

Title:

Authors:
Steffan, Ilse
Vujičić, Goran (183371)
Journal: Mikrochim.Acta
ISSN: 0026-3672
Volume: 110
Year: 1993
Pages: from 89 to 94
Number of references: 18
Language: engleski
Summary: A method is described for the determination of cobalt, molybdenumand vanadium in mineral water samples by inductively coupledplasma-atomic emission spectroscopy (ICP-AES) after separation ofthese elements from the matrix by ion exchange. The samples areacidified with concentrated hydrochloric acid (10 ml/l) and theelements are adsorbed as thiocyanate complexes. Elution isperformed with a mixture 2 M in perchloric acid and 1 M inhydrochloric acid and subsequently with 1 M hydrochloric acid.After evaporation of the eluates and dissolution of the residuethe volume of the measuring solution for ICP-AES is 10 ml. Therecoveries for Co, Mo and V at a concentration level of 1(micro)g/l mineral waters were approximately 99%. A concentrationfactor of 100 is achieved by this procedure.
Keywords: ICP-AES, mineral waters, cobalt, molybdenum, vanadium

Title:

Authors:
Alihodžić, Sulejman (161135)
Đinić, Mladen (55613)
Klaić, Branimir (21025)
Kiralj, Rudolf
Kojić-Prodić, Biserka (21602)
Herceg, Marija (15620)
Cimerman, Zvjezdana (91635)
Journal: Tetrahedron.Lett.
Number: 51
ISSN: 0040-4039
Volume: 34
Year: 1993
Pages: from 8345 to 8348
Number of references: 14
Language: engleski
Summary: Novel fluoroionophores bearing two (1) and one (2)fluorophoric-6-phenanthridinylunits attached by a short methylenespacer onto nitrogen atoms of 7,16-diaza- and aza-18-crown-6rings have been prepared in high yields. The fluoroionophoresexhibited the ability to signal binding of certain metal cationsthrough the specific complexation induced shifts (CIS) ofphenanthridine protons in 1H NMR spectra as well as by the largeintensity enhancements in fluorescence spectra. The X-raystructure analysis of /1,K+(C2H4Cl2)/ picrate complex revealedthat K+ is nine-coordinated, using all donors from the diazacrownring, one chlorine atom from 1,2-dichloroethane solvent moleculeand both nitrogen donors from syn-oriented phenanthridine units.
Keywords: fluoroionophores, phenanthridinyl units, diaza-crown, aza-crown, X-ray structure, spectrofluorimetry

Title: Effects of Low Acetic Acid Concentrations in Inductively Coupled Plasma Atomic Emission Spectrometry

Authors:
Rončević, Sanda (164890)
Široki, Marija (47105)
Journal: J. Anal. At. Spectrom.
Number: -
ISSN: 0267-9477
Volume: 9
Year: 1994
Pages: from 99 to 104
Number of references: 16
Language: engleski
Summary: The effects of low acetic acid concentration on selected analytical lines (Mn II, Li I, Cu I, Cu II, Cd I and Cd II) were studied as a function of incident power and carrier gas flow rate, using an ARL 35000 C inductively coupled plasma spectrometer. Line intensity and line-to-background intensity ratios were measured for water and for 3 and 10% acetic acid. The magnitude and mechanism of interference produced by acetic acid were revealed from measured changes in the solution uptake rate,the departure of the ratio of line intensity in acetic acid solution and that in water from units and the changes inion-to-atom line intensity ratio. Trace metal determination in 3% acetic acid, used as a "model" solution in health control of packing materials, and in 9-10% vinegar was carried out by direct aspiration of sample into the plasma at compromise conditions for multi-element analysis(r.f. power, 1200 W and carrier gas flow rate, 0.9 l min-1) using matrix-matched calibration standards. Detection limits and relative standard deviation values for Fe, Cu, Cr, Ni, Pb, Al, Cd and Zn were almost equal for aqueous solution and solutions of 3 and 10% acetic acid.
Keywords: Inductively coupled plasma spectrometry, acetic acid, trace metals

Title: The structure and tautomeric properties of 2-(3-pyridylmethyliminomethyl)phenol

Authors:
Cimerman, Zvjezdana (91635)
Kiralj, Rudolf
Galić, Nives
Journal: J. Mol. Struct.
ISSN: 0022-2860
Volume: 323
Year: 1994
Pages: from 7 to 14
Number of references: 23
Language: engleski
Summary: The structure and properties of 2-(3-pyridylmethyliminomethyl)phenol have been determined by X-ray crystallography, NMR, UV and IR spectroscopy and compared with the characteristics of the Schiff bases derived from salicylaldehyde and aminopyridines. Crystal data: C13H12N2O, Mr = 212.250, monoclinic, space group P21/n,a = 10.49(1)A, b = 9.002(4)A, c = 12.42(1)A, beta = 109.10(4)o, V = 1109(2)A3, Z = 4, Dx = 1.271 g cm-3, MoK(alfa) (lambda = 0.71073 A), mi = 0.8 cm-1, F(000) = 448, T = 297 K, R = 0.049, Rw = 0.053 for 886 reflections with I > 2(sigma)(I). Bond distances and bond angles are similar to those of 2-(pyridyliminomethyl)phenols. In the title molecule the dihedral angle between the pyridine and benzene least-squares planes is 89.9(2)o. There is an intramolecular O1-H...N1 hydrogen bond of 2.572A. In solutions of polar solvents tautomeric interconversion of the Schiff base into the ketoamine is observed. Corresponding equilibrium constants are estimated in a variety of solvents on the basis of UV spectral data.
Keywords: Schiff bases, salicylaldehyde, 3-aminomethylpyridine, ketoamino-enolimino tautomerism, x-ray analysis

Title:

Authors:
Modrić, Nevenka
Poje, Mirko
Gojmerac Ivšić, Astrid (78124)
Journal: Biorg.Med.Chem.Lett.
Number: 14
ISSN: 0960-894x
Volume: 4
Year: 1994
Pages: from 1685 to 1686
Number of references: 12
Language: engleski
Summary: Evidence for the species trapped by trimethylsilylation in peroxidase mediated oxidation of urate (1) having the tetrakis(trimetihylsilyl)spirodihydantoin (4b) structure is provided by its hydrolysis, reaction with diazomethane, and actual isolation and identification of tetramethylspirodihydantoin (4c).

Title:

Authors:
Marić, Ljiljana (28365)
Široki, Marija (47105)
Journal: Anal. Chim. Acta
ISSN: 0003-2670
Year: 1995
Number of references: 28
Language: engleski
Summary: The extraction of 4-(2-pyridylazo)resorcinol (PAR) and 4-(2-thiazolylazo)resorcinol (TAR) with chloroform alone and in the presence of tetraphenylarsonium and tetraphenylphosphonium chlorides (Ph4XCl) was studied. In the optimum pH range 3.5-5 for PAR and 1.5-5 for TAR, 94-95% of the reagents was extracted into chloroform. In the presence of Ph4XCl in 10 - 100-fold excess 95-98% of PAR and TAR was extracted within the pH range 3.5-10 and 1.5-10 respectively. The species extracted with chloroform alone were estimated to be H2R molecules. A quantitative interpretation of PAR and TAR distribution between aqueous solution (mi = 0.33) and chloroform was made. Distribution constants for H2R were determined as 14.9 for PAR and 19.2 for TAR. In the presence of Ph4XCl as extractant H2R molecules were predominantly extracted up to pH 4; between pH 4 and pH 8 two species H2R and Ph4X+HR- were transferred to the chloforom phase. Above pH 8 the Ph4X+HR- ion pairs were the only extracted species. They were studied in solution and by characterization of solid compounds isolated from the organic phase and aqueous solution.
Keywords: extraction, 4-(2-pyridylazo)resorcinol, 4-(2-thiazolylazo)resorcinol, tetraphenylarsonium, tetraphenylphosphonium

Title:

Authors:
Alegretti Živčić, Vlasta (29910)
Herak, Marko (15552)
Journal: Croat.Chem.Acta
ISSN: 0011-1643
Year: 1995
Number of references: 12
Language: engleski
Summary: Molybdenum(VI) was reduced to its pentavalent state by ascorbic acid in the hydrochloric acid medium. The diminishing orange-red colour of the unstable molybdenum(V)-thiocyanate complex was stabilized by the addition of low alcohols and by extraction either into chloroform or into butanol. Spectrophotometric measurements followed the extraction procedure. All the investigated systems obeyed Beer's law (lambda max = 465 nm), molar absorptivities covering the range from 1.40x104 to 3.1x104 l mol-1cm-1 depending on the system type. Based on the equilibrium shift method a reaction mechanism is proposed with MoO(NCS)3 as the extracted species solvated by each of the alcohols added.
Keywords: molybdenum-thiocyanate, alcohols, extraction

Title:

Authors:
Vojković, Vlasta (52801)
Gojmerac Ivšić, Astrid (78124)
Tamhina, Biserka (49080)
Journal: Solv.Extr.Ion Exch.
ISSN: 0736-0299
Year: 1995
Number of references: 8
Language: engleski
Summary: The extraction of tantalum(V) from aqueous oxalic solution with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) dissolved in chloroform in the presence of an excess of thiocyanate and perchlorate ions was examined at different acidities and ionic strengths. Thiocyanate and perchlorate ions produced a synergistic effect on the tantalum extraction with HX. In the presence of an excess of thiocyanate or perchlorate ions tantalum(V) was quantitatively extracted from a more acidic solution (pH 2.3 - 3 M H2SO4) with less excess of HX and in the presence of a higher concentration of oxalic, tartaric or citric acids or their anions. Optimum conditions for the extraction of tantalum(V) as a mixed thiocyanate-HX or perchlorate-HX complex from the aqueous phase of different composition were determined. The compositions of the extracted complexes were studied and discussed.
Keywords: tantalum, 4-pyridone, extraction, thiocyanate, perchlorate


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