Chemistry Journal of Moldova

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DOI: dx.doi.org/10.19261/cjm.2008.03(1).02

Graphical Abstract: Mixtures of small quantities of carbonyl compounds are presents in foods, concerning sensorial qualities. The inferior carbonyl compounds (C2-C4, boiling point <100°C) – mono and dicarbonyl – can be identified and measured their concentrations, after a separation by distillation on the water bath. They are transferred in a strongly acid solution of 2.4-dinitrophenylhidrazine (2.4-DNPH), generating a mixture of insoluble 2.4-dinitrophenylhidrazones (2.4-DNPH-ones). The 2.4-DNPH-ones are organic compounds with weak polarity, solids, crystallized, yellows and water insoluble, soluble in organic solvents. The mixture of 2.4dinitrophenylhidrazones may be separated by liquid chromatography, using the reverse phase mechanism [1-3]. This paper contains experimental and theoretical considerations to the means of separation through liquid chromatography of two synthetically and a natural mixtures that contain 2.4-DNPH-ones provided by inferior carbonyl compounds; to obtain conclude results, in the synthetically mixtures was introduce and 2.4-DNPH-ones provided by carbonyl compounds having three (acetone and propanal) and four (isobutyl aldehyde) atoms of carbon.


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DOI: dx.doi.org/10.19261/cjm.2008.03(1).03

Graphical Abstract: An equimolar mixture of 2.4-dinitrophenylhidrazones (2.4DNPH-ones) providing by acetaldehyde and diacetyl must be analyzed by liquid-chromatographic separation, using the mechanism of repartition with reverse phase; that full papers is for identification the optimal analytical conditions. As mobile phase are utilized various binary mixtures eluent, containing water and methanol, with 0-45% water. By the experimental studies were identified four domains of behavior and two optimal binary mixtures, with 25% and 45% water, thus this is a study on the behavior of binary mixtures mobile phases. The peaks are characterized by values of retention times and by position. The separation processes were appreciated by difference between the retention times of peaks; if the percent of water increase, the values of retention times is higher. When the percent of water is 45%, the difference between the retention times is maxim, associated with a change of peaks position.


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DOI: dx.doi.org/10.19261/cjm.2008.03(1).04

Graphical Abstract: The present work presents the results obtained during investigation of the zinc content of the water and river sediments in an area polluted by mining activities, to provide information on the mobility and availability of this element. Sediment and water samples have been collected from significant sites in a former mining area in which with some sterile pits, which represent a major environmental hazard.


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DOI: dx.doi.org/10.19261/cjm.2008.03(1).05

Graphical Abstract: Iodine deficiency is the most prevalent micronutrient deficiency in the world today. Food fortification is an important compliment to food-based approaches, and iodine fortification of foods as one of the strategies for the control of iodine deficiency. Manufacturing and consumption of sunflower oil fortified with iodine as well as derivative products on it basis is a perspective direction for elimination of alimentary dependent iodine deficiency disorders. The present work examines morphological changes in the thyroid system of rats at the experimental mercatholile-induced hypothyroidism. As well it determines the influence of iodinated oil and margarine on the thyroid system of rats. It specifies the safe value of iodinated oil and margarine for rats. In-vivo study demonstrated the efficacy of fortification of lipid products with iodine under iodine deficiency status.


Downloads: 15

DOI: dx.doi.org/10.19261/cjm.2008.03(1).06

Graphical Abstract: This short communication presents several preliminary results obtained during kinetic investigation of dihydroxyfumaric acid decarboxylation. The reaction order towards the hydrogen ions concentration has been established, the correlation between the decarboxylation velocity and temperature has been found, the Arrhenius equation for the decarboxylation constant has been drawn.

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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2008.03(1).07

Graphical Abstract: The paper describes the analytical potentialities of the trinuclear chromium(III) complexes as potentiometric ionophores for the construction of electrodes sensitive to the presence of nitrate anion. The electroactive material containing 4,4’-bipyridil was synthesized in situ. The membrane was prepared using dioctylphthalate as a solvent mediator and poly (vinyl chloride) as a polymeric matrix. The electrodes presented a slope of 56 mV/decade, a low limit of detection (3,2.10-6 mol/l), an adequate lifetime (4 months), and suitable selectivity characteristics when compared with other nitrate electrodes. The good parameters of this electrode made possible its application to the determination of nitrate in different types of fertilizers.


Downloads: 12

DOI: dx.doi.org/10.19261/cjm.2008.03(1).08

Graphical Abstract: The ground state was calculated to be a quintet, which means a ferromagnetic interaction between centers. The