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, 1995 ). NO is supplied by two pathways, the classical l -arginine-nitric oxide synthase pathway, and the later discovered nitrate-nitrite-nitric oxide pathway ( Lundberg et al., 2008 ; Weitzberg et al., 2010 ). Dietary nitrate is one of the main

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67 Lechowich, R. V., Brown, W. L., Deibel, R. H. & Somers, I I. (1978): The role of nitrite in the production of canned cured meat products. Fd Technol. , 5 , 45

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Even if plants can contain high levels of nitrate and nitrite, milk and dairy products are not described as sources of these anions. The purpose of this paper was to measure the concentrations of nitrate and nitrite in forage, cow blood, and milk.The results show that the nitrate ratio of milk to plasma is very low, suggesting that milk contamination with nitrate is unlikely to occur. This finding also proves the lack of an active transport mechanism to transfer nitrate from blood to milk. The nitrite anion almost disappears from milk through an enzymatic conversion; usually levels of μg l−1 were measured.

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. Duranski , M. R. , Greer , J. J. , Dejam , A. , Jaganmohan , S. , Hogg , N. , Langston , W. et al. ( 2005 ) Cytoprotective effects of nitrite during in vivo ischemia-reperfusion of the heart and liver . J. Clin. Invest. 115 , 1232 – 1240

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A capillary isotachophoretic (cITP) method to determine the concentration of nitrates and nitrites in vegetables and lactic acid fermented tomato, cucumber and cucumber-onion juices is described. Method characteristics (selectivity, response function, linearity, precision, accuracy and limit of quantification) were determined. The minimal sample pretreatment and relatively low running make isotachophoresis a good alternative to existing methods.

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All boarding school provisions within the Slovak Republic are due to prepare meals under the guidance of the Ministry of Health that monitors recommended daily intakes of individual foods and dietary allowances of nutrients through scientific meetings. Calculations based on a nutrition model of a boarding school in four months were done to estimate the mean dietary intake of nitrates and nitrites, industrially added to foodstuffs, by children aged 7 to 10 years. Following recognised methodology of the Codex Alimentarius and the European Commission, it was assumed that nitrates and nitrites are used in the widest possible range of foods and at their maximum permitted levels, resulting in overestimation of intake values. The mean daily exposure of consumers with the lowest (21 kg) and the mean (26.5 kg) body mass to nitrates ranged from 0.6 to 6.7% and from 0.5 to 5.3% of their acceptable daily intake (ADI), respectively. For the same consumers, the mean daily exposure to nitrites ranged from 0 to 13.0% and from 0 to 10.3% ADI. No significant seasonal differences were obvious. The results indicated that the above-mentioned group of children is sufficiently protected from hazard of nitrates and nitrites in food.

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Abstract  

The capillary electrophoresis method with direct UV detection is proposed for the determination of nitrite and nitrate in high-salt perchlorate solutions issued from uranium carbide dissolution. The isotachophoretic sample stacking was used to compensate for the perchlorate matrix interference. Simple electrolyte composed of 120 mM formiate buffer, pH 3.8 enabled the nitrate and nitrite determination in the presence of up to 1000-fold excess of perchlorate with 2 µM and 4 µM detection limits for nitrate and nitrite, respectively. The proposed method was applied to the determination of nitrate and nitrite in high-salt non-irradiated uranium carbide dissolution samples.

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Six alkali metal nitrates and nitrites were evaporated in vacuum at a constant heating rate in a combined mass spectrometric and thermogravimetric apparatus. Time resolved profiles of decomposition gases and kinetics were obtained for LiNO3, NaNO3, KNO3, Na/KNO3, NaNO2 and KNO2. Activation energies for the evaporation of these salts were calculated and compared to previous results of isothermal experiments. In the temperature range 650–850 K, the decomposing nitrates released NO, N2 and O2 while the nitrites released only NO and N2.

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The thermal decomposition of sodium nitrite or nitrate pre-adsorbed upon TiO2 surfaces has been investigated by employing several techniques as infrared spectroscopy (IR) and temperature programmed desorption in conjunction with mass spectrometry analysis (TPD-MS) to study the features observed during these thermal decompositions. Differential thermal analysis (DTA) in combination with X-ray diffraction analysis (XRD) were used to investigate the possibility of a solid state chemical reaction between the solid products originated from the thermal decomposition of the pre-adsorbed species and the TiO2. On the basis of our results, various characteristic features of these thermal decomposition reactions will be discussed.

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Abstract  

The present paper reports the regioselective [15NO2]-labeling of N-methoxy-2,4,6-trinitroaniline and 2,2-diphenyl-1-picrylhydrazine (reduced DPPH). Starting from N-methoxy-2,6-dinitroaniline, or N-methoxy-2,4-dinitroaniline, nitration in methylene chloride with solid sodium [15N]nitrite and 15-crown-5-ether afforded N-methoxy-2,6-dinitro-4-[15N]nitroaniline and N-methoxy-2,4-dinitro-6[15N]nitroaniline, respectively. The same compounds could be prepared in higher purity by nitrodecarboxylation (ipso-substitution) under the same conditions starting from N-methoxy-4-carboxy-2,6-dinitroaniline (4-methoxyamino-3,5-dinitrobenzoic acid) and N-methoxy-2-carboxy-4,6-dinitroaniline (2-methoxyamino-3,5-dinitrobenzoic acid). Similarly,ipso-substitution of 2,2-diphenyl-1-(4-carboxy-2,6-dinitrophenyl)-hydrazine afforded, under the same reaction conditions, 2,2-diphenyl-1-(2,6-dinitro-4-[15N]nitrophenyl)-hydrazine. By1H-NMR and13C-NMR it was also observed that under these reaction conditions a14NO2 group can be replaced by a15NO2 group.

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