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Transformations of nitrates, nitrites, N-nitrosamines formation and utilization of inhibitors in redox processes

Author: Gonţa Maria
Degree:doctor habilitat of chemistry
Speciality: 02.00.04 - Physical chemistry
Scientific consultant: Gheorghe Duca
doctor habilitat, professor, Moldova State University
Scientific council:


The thesis was presented on the 19 December, 2008
Approved by NCAA on the 26 February, 2009


Adobe PDF document1.05 Mb / in romanian


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281 pages


The thesis comprises studies in the field of nitrosation of secondary aliphatic cyclic amines and amides, under the influence of nitrite-ions. It also contains investigations regarding the inhibition of these processes by diminishing the concentration of nitrosating agents and substrates under the action of reductons obtained from secondary winery products. As a result of computational evaluation of concentrations of the species formed during the nitrosation of various substrates, the initial and equilibrium concentrations have been determined. Thus, it has been shown that the concentration of the nitrosating agent N2O3 is almost two fold greater than the concentration of NO+.

It was found that the inhibition of the nitrosation process involving secondary aliphatic amines and amides is determined by the interaction of the investigated reductons with nitrosating agents, followed by their inactivation. In the case of morpholine nitrosation, the mechanism of inhibition of N-nitroso morpholine formation under the action of dihydroxyfumaric acid esters and tartaric acid also includes their interaction with nitrosatable substrates. The inhibition constants were calculated for the nitrosation of morpholine in the presence of various reductons, and it has been shown that the dihydroxyfumaric acid exhibits the highest inhibition rate. The formation of tobacco specific N-nitrosamines at various technological steps were investigated and inhibition methods were elaborated for the prevention of nitrosamines formation during fermentation, by using dipotassium tartrate.

The inhibitory action of dihydroxyfumaric acid and mono sodium dihydroxyfumarate on the nitrosation of metabolites formed in the gastric juice. It was found that during the proteolysis of casein and albumin under the action of proteolytic enzymes, these reductons inhibit N-nitroso compounds formation, and have no influence on the content of unhydrolyzed protein substrate and on the concentration of formed amino acids. The antioxidant/antiradical activity of reductons obtained from secondary winery products were investigated using the DPPH – radical method and the ABTS+· - cation radical method.

For the first time, it has been shown that DFH3Na decreases the rate of formation of MetHb during HBO2 oxidation with nitrite-ions, by decreasing the acceleration factor along with the increase of reducton’s concentration, and the mechanism of DFH3Na action, which is based on its interaction with OH•, as well as HO2• radicals, formed during the initiation step, was described. The conditions for water treatment against the excessive presence of nitrite and nitrate ions were optimized. It has been found, that in order to decrease the concentrations of these ions to the maximum allowed dose, the efficiency of treatment with soluble magnesium anodes, as opposed to aluminum, is higher at a lower electricity quantity (180- 600 C ); along with the increase of Q (600- 900 C) the efficiency becomes maximal for the electrochemical treatment with aluminum anodes.