Chemistry Journal of Moldova

Analytical chemistry

BUFFER CAPACITY IN HETEROGENEOUS MULTICOMPONENT SYSTEMS. REVIEW

Author(s):

Oxana Spinu, Igor Povar


Field: Analytical chemistry
Type: Review
Issue: 2015 Volume 10, no.2
Pages: 8-25
Keywords: buffer action, complex formation, thermodynamic stability, extraction multicomponent system, heterogeneous equilibria.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(2).01

Graphical Abstract:
 The quantitative basis of the theory of buffer properties for two-phase acid-base buffer systems and for multicomponent heterogeneous systems has been derived. The analytical equations with respect to all components for diverse multicomponent systems were deduced. It has been established, that the buffer capacities of components are mutually proportional.


Downloads: 57

METHOD OF INFRARED SPECTRA REGISTRATION OF ACTIVATED CARBONS IN POTASSIUM BROMIDE PELLETS

Author(s):

Diana Shepel, Tatiana Goreacioc, Tudor Lupascu, Mihail Filippov, Maria Rusu


Field: Analytical chemistry
Type: Short communication
Issue: 2015 Volume 10, no.1
Pages: 113-115
Keywords: infrared spectroscopy, activated carbons, potassium bromide KBr pellets.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).16

Graphical Abstract:
 This communication is devoted to the elaboration of a new optimal technique of infrared spectra registration of activated carbons in potassium bromide pellets. Authors investigated the dependence of the intensity of the least overlapping infrared bands of activated carbons on the conditions of preparation, recording of the spectrum, and the degree of homogenization with potassium bromide.


Downloads: 34

METHOD FOR NITRATE DETERMINATION IN WATER IN THE PRESENCE OF NITRITE

Author(s):

Maria Sandu, Tudor Lupascu, Anatol Tarita, Tatiana Goreacioc, Sergiu Turcan, Elena Mosanu


Field: Analytical chemistry
Type: Research paper
Issue: 2014 Volume 9, no.2
Pages: 8-13
Keywords: water, nitrate determination, nitrites, sulfaminic acid, Griess reagent, reducing mixture
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2014.09(2).01

Graphical Abstract:
 The study relates to determination of nitrate in presence of nitrite in water and can be used in the quality monitoring of natural water (surface and groundwater), drinking water, water from fish farms and public aquaria where autonomous filters is used. The nature and quantity of reagents used have insignificant impact on natural waters and sewages. According to the investigation, the method includes the removal of nitrite from the solution/water with sulfaminic acid, the nitrate ion reduction to nitrite using a reducing mixture that contains Na2SO4 and zinc dust in ratio of 100:5 and determining the nitrite with the Griess reagent.


Downloads: 50

STUDY OF SOME ARCHAEOMETRIC CHARACTERISTICS USED IN PANEL PAINTING ICONS AUTHENTICATION

Author(s):

Raluca Anamaria Cristache, Ana Maria Budu, Petronela Spiridon, Viorica Vasilache, Ion Sandu


Field: Analytical chemistry
Type: Research paper
Issue: 2014 Volume 9, no.2
Pages: 14-18
Keywords: icon, historic paper, SEM-EDX, micro-FTIR
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2014.09(2).02

Graphical Abstract: 
The authentication of cultural heritage assets is a complex process of scientific investigation which regards obtaining information about: author (painter), the period when it was made, the owners and other data related to the main contexts of their evolution in time (routes travelled). This work presents a comparative study of the paper used in the preparation layer of three icons painted in Russian style. As an analysis techniques were used the micro and macro photography assisted by Optical Microscopy (OM), SEM-EDX and micro-FTIR.



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CATALYTIC WAVE OF CHLORATE IONS IN THE PREZENCE OF THE MOLYBDENUM (VI) - 2,3-DIHYDROXYBENZALDEHYDE COMPLEX

Author(s):

Ludmila Kiriyak, Tatiana Cazac, M. Revenco, and I. Povar


Field: Analytical chemistry
Type: Research paper
Issue: 2010 Volume 5, no.2
Pages: 24-29
Keywords: Voltammetry, catalytic current, molybdenum, 2,3-dihydroxybenzaldehyde, potassium chlorate.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2010.05(2).02

Graphical Abstract:
The polarographic catalytic current in acid solutions of Mo(VI), 2,3-dihydroxybenzaldehyde (2,3-DHBA) and chlorate ions has been investigated. The scheme of reactions taking place in the solutions and on the electrode has been elaborated. The increase of the catalytic current is explained by the formation of the active intermediate complex [Mo(V)×2,3-DHBA (ClO3-)]. The rate constant of formation for the active intermediate complex K = 2.5 × 106 mol-1 × dm3 × s-1, the activation energy of reaction Ea=14.0 kcal×mol-1 and the activation entropy ∆Sa¹= -28.3 e.u. have also been determined.

Downloads: 14

THIOCYANATE ION-SELECTIVE PVC MEMBRANE ELECTRODE

Author(s):

Mihail Revenco, Mariana Martin, Waell Abu Dayyih


Field: Analytical chemistry
Type: Research paper
Issue: 2010 Volume 5, no.1
Pages: 73-77
Keywords: thiocyanate, potentiometric sensor, titration.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2010.05(1).05

Graphical Abstract: 
A potentiometric selective sensor based on trinuclear chromium(III) complex as a novel ionophore for the thiocyanateselective electrode is reported. The sensor displays a near Nernstian slope of 57 ± 2 mV per decade, over a wide pH range 3 - 11. The working concentration range of the electrode is 1.10-5 – 1.10-1 mol/l with a detection limit of 5.10-6 mol/l. The sensor has a response time of 20 s and can be used for at least 6 months without any considerable fluctuation of the potential. The selectivity coefficients determined at using the fixed interference method indicate a good discriminating ability towards other anions. The prepared sensor was applied as an indicator electrode in the titration of thiocyanate with Ag+.

Downloads: 13

STUDY CONCERNING THE CORROSIVE ACTIVITY PROPERTIES OF MONATOMIC ALCOHOL-GASOLINE BLENDS

Author(s):

Valerian Cerempei


Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.2
Pages: 36-44
Keywords: mixture, butanol, ethanol, corrosion, gasoline, resistance, triethylamine.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(2).09

Graphical Abstract:
 The paper studies the corrosive activity of the monatomic alcohol (ethanol, butanol) - gasoline mixtures on the materials from which the internal combustion engines are made. The corrosive influence of these blends was determined in dependence of their composition. It was established that the addition of butanol and triethylamine in the ethanol-gasoline mixture essentially reduces the corrosive activity of this mixture.

Downloads: 11

DETERMINATION OF COPPER AND ZINC IN MINERAL WATERS BY ATOMIC ABSORPTION SPECTROPHOTOMETRY

Author(s):

Tatiana Mitina, Nadejda Bondarenko, Oxana Bunciuc


Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.2
Pages: 45-47
Keywords: mineral waters, microelements, atomic absorption spectrometry.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(2).10

Graphical Abstract: 
The content of copper and zinc in mineral waters were determined by atomic spectroscopy with preliminary extraction of metals. Validation of the technique was carried out by the method of standard additions and proved the reliability of analytical data.

Downloads: 16

PHYSICOCHEMICAL PROPERTIES OF THE GASOLINE AND ALCOHOL BIOFUEL MIXTURES

Author(s):

I. Povar, V. Cerempei and B. Pintilie


Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.2
Pages: 48-52
Keywords: alcohol, biofuel, distillation curves, gasoline, Reid saturated vapour pressure, specific gravity.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(2).11

Graphical Abstract:
 The influence of added alcohols, ethanol and butanol, on the main biofuel properties, such as the specific gravity, Reid saturated vapour pressure and distillation curves have been investigated. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. This research proves the possibility of obtaining fuels with different levels of resistance to detonation, using gasoline with different chemical components and various fractions of alcohols.

Downloads: 15

PHASE STABILITY OF MONOATOMIC ALCOHOL-GASOLINE MIXTURES FOR DIFFERENT COMPOSITIONS AND HYDRODYNAMIC CONDITIONS

Author(s):

Valerian Cerempei


Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 73-76
Keywords: butanol, ethanol, gasoline, mixtures, phase stability.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(1).08

Graphical Abstract:
 The article investigates phase stability for the mixtures of monoatomic alcohols (ethanol, butanol) with gasoline in the presence of water. There have been determined the optimal storage conditions of mixtures depending on their composition and mixing conditions. The positive influence of butanol on the phase stability of ethanol-gasoline mixtures was detected.

Downloads: 9