Nitrite In Aqueous Solution Research Articles

Modeling the nitrosation kinetics in simulated natural environmental conditions∗

The rate of N‐nitrosodibutylamine formation from dibutylamine and nitrite in aqueous solutions was studied in the presence of soil derived fulvic acids. The nitrosation rate was enhanced in fulvic acid mediated systems even at near neutral acidity (pH ∼ 7.00) environments. The generalized rate law is consistent with consecutive reaction series and can be simplified as k1[(C4H9)2NH][FA] at excessive fulvic acid concentrations.

Reaction of Nitrite with Ascorbic Acid or Ascorbic Acid‐2‐Derivatives

ABSTRACTThe decrease in free nitrite in aqueous solutions of nitrite and ascorbic acid (AsA), ascorbic acid‐2‐phosphate (AsA‐2‐P) or ascorbic acid‐2‐sulfate (AsA‐2‐S) was studied. Both AsA‐2‐P and AsA‐2‐S reacted with nitrite as did AsA. The rate of the reaction followed the order AsA > AsA‐2‐P > AsA‐2‐S. The reaction solution of AsA and nitrite did nitrosate cytochrome c and regenerate nitrite, but the reaction solution of nitrite with either AsA‐2‐P or AsA‐2‐S did not. When surimi with myoglobin added as a pigment was used as a model meat curing system, the addition of AsA‐2‐P and AsA‐2‐S did not participate in the reactions resulting in development of cured meat color.

Determination of Low Concentrations of the Azo-Dye Complex of Nitrite in Fresh Water and Seawater Using Surface-Enhanced Resonance Raman Spectroscopy (SERRS)

A highly sensitive and selective method for the determination of low concentrations of nitrite in aqueous solutions using surface-enhanced resonance Raman spectroscopy (SERRS) is presented. The SERRS-active substrate was silver hydrosol. In order to induce the SERRS effect, nitrite was transformed into a colored product (an azo dye) by a standard chemical reaction. The detection limit for nitrite is 0.02 nM in distilled water, and analytical calibration curves yield straight lines in the concentration range below 30 nM. The sensitivity of this method is better than that of colorimetry and other techniques such as chemiluminescence. This improvement indicates that SERRS shows great promise as a useful analytical tool for trace analysis of nitrite and dyes.

Determination of nitrite as pentafluorobenzyl derivative by RP-HPLC and UV detection with and without ion-pair extraction

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV detection (270 nm) for the determination of nitrite as its pentafluorobenzyl derivative with and without ion-pair extraction is described. Ion-pair extraction of nitrite from aqueous solutions was performed by using a 1 mol/l solution of the liquid ion exchanger methyltrioctylammonium chloride in toluene. The residue of the ion-pair extraction or an aliquot of an aqueous nitrite solution or of a biological fluid (100 μl) were treated with 400 μl of acetone and 10 μl of pentafluorobenzyl bromide. Nitrite was converted into its pentafluorobenzyl derivative by heating at 50°C for 90 min. After evaporation of acetone the aqueous phases were diluted with 100 to 400 μl of methanol, and up to 100 μl were injected into the RP-HPLC system. The method allows accurate analysis of nitrite in the presence of nitrate directly in aqueous solutions and biological fluids in concentrations down to 2.0 mg/l. The method is also applicable to the determination of nitrate following its reduction to nitrite by cadmium.

Vitamin B 12 as coordinating agent for the voltammetric determination of nitrite in natural waters

The determination of trace amounts of nitrite in aqueous solutions is possible in the presence of vitamin B 12 (added in the form of cyanocobalamin) as coordinating agent via adsorptive accumulation of nitric coordinated to vitamin B 12 at a stationary mercury drop electrode, followed by fast-scan differential-pulse voltammetry. The calibration graph is linear in the concentration range of nitrite from 0.1 to 100 μmol l −1, with a detection limit calculated as 0.02 μmol l −1 or 1 μg l −1 of nitrite. Nitrate, chloride, sulphate and phosphate do not interfere but sulphite, dithionate and cadmium(II) do. The method was applied to the determination of nitrite in drinking and river waters.

Analysis of nitrite in aqueous solutions containing concentrated matrix ions using an octadecyl‐poly(vinyl alcohol) gel microbore column and an electrochemical detector

Analysis of nitrite in aqueous solutions containing concentrated matrix ions using an octadecyl‐poly(vinyl alcohol) gel microbore column and an electrochemical detector

Nitrosation of some food‐related tetrahydro‐β‐carboline‐3‐carboxylic acids

AbstractA number of β‐carbolines whose nitroso derivatives are known mutagens and carcinogens are formed in cooked and processed foods. In this work the formation of N‐nitroso derivatives from 1‐substituted‐1,2,3,4‐tetrahydro‐9H‐pyrido[3,4‐b]indole‐3‐carboxylic acid (1‐R‐THBC‐3‐COOH) and nitrite in aqueous solution was studied. The effect of reaction pH, nitrite concentration and duration of the reaction was evaluated. The yield of N‐nitroso‐1‐R‐THBC‐3‐COOH at 37°C was enhanced at low pH(about pH 2) and reached a maximum within 1 h when the stoichiometric amount was used in the reaction. Formation of the nitroso derivative was detected even when only half the stoichiometric quantity was used.

ChemInform Abstract: Formation of Mutagens by Photochemical Reaction of 2‐Naphthol in Aqueous Nitrite Solution.

AbstractIrradiation of 2‐naphthol (I) in the presence of sodium nitrite (II) yields a mixture of the compounds (III) ‐ (IX).

Formation of mutagens by photochemical reaction of 2-naphthol in aqueous nitrite solution.

The following seven compounds were isolated from the photoreaction products of 2-naphthol in aqueous nitrite solution by silica gel chromatography and high performance liquid chromatography : 1-nitro-2-naphthol (Fp-2), 1-nitroso-2-naphthol (Fp-3), isocoumarin (Fp-4(1)), 5- or 8- nitro-2-naphthol (Fp-5(1)), a monoquinonoid dimer of 2-naphthol (Fp-5(2a)), a dinitro-2-naphthol (Fp-6(1)) and 1, 2-naphthoquinone. Among these compounds, the three nitro compounds, Fp-2, Fp-5(1) and Fp-6(1), and isocoumarin exhibited a weak mutagenicity towards S. typhimurium TA98 without S9 mix. Although no major mutagen was isolated, it was found that irradiation of the solution of non-mutagenic Fp-5(2a) with nitrite and of the mixed solution of 1, 2-naphthoquinone and Fp-2 without nitrite resulted in the formation of further mutagenic compounds. From these results, it is concluded that not only nitration but also quinone production is closely related to photochemical mutagen formation.

Roles of oxygen in photochemical reaction of naphthols in aqueous nitrite solution and mutagen formation.

Roles of oxygen in photochemical reaction of naphthols in aqueous nitrite solution and mutagen formation.

Dietary fat and N-nitrosation in the rat.

1. Groups of four conventional (CV) rats ate natural or purified diets either with or without 100 g fat/kg and drank 0.235 M-sodium nitrate. The fats tested were butterfat, coconut oil, olive oil, maize oil and safflower oil. 2. Decreased urinary excretion of N-nitrosoproline (NPRO) was observed in rats fed on fat-supplemented diets compared with those fed on low-fat diets, with butterfat having the greatest effect of the fats tested. 3. Reduced excretion of NPRO was not the result of inhibition of the intragastric N-nitrosation reaction or absorption of nitrosamine from the gastrointestinal tract. 4. The availability of nitrite in aqueous solution was decreased by the fat diets but the effect was similar in all the fats tested. 5. Nitrate reductase activity was present in the forestomach contents of CV rats at pH greater than 4 and was apparently inhibited by feeding a fat diet. No nitrate reductase activity was detected in stomach contents of germ-free rats. 6. Nitrate reductase activity in stomach and small intestinal tissue was not altered by feeding a fat diet. 7. It was concluded that nitrate reductase activity in stomach contents was of microbial origin and the decreased urinary excretion of NPRO on feeding the fat diets was mainly due to the inhibition of nitrate reductase activity in stomach contents.

Spectrophotometric Determination of Nitrite in Aqueous Solution by the Diazotization-Coupling Method with p-Am i noacetophenone-N-(1-Naphthyl)ethylenediamine

Abstract A sensitive spectrophotometric method for the determination of nitrite is worked out. It depends on the reaction of the intended ion with an acidified p-aminoacetophenone solution to form a diazonium cation, which is subsequently coupled with N-(1-naphthyl)ethylenediamine to form a reddish purple colored water-soluble and intenseazo dye with maximum absorption at 550nm. The curve of absorbance versus concentration is linear, indicating that Beer's law is obeyed over the range 1–20μg of nitrite in a final volume of 25ml, i.e., 0.04–0.8ppm, with a molar absorptivity of 5.75 × 104Imol−1 cm−1, a relative error of -0.8 to + 1.2% and a relative standard deviation of 0.1–2.7%, depending on the level of determinand concentration. The optimum conditions affecting the color reaction and interference due to foreign ions have been examined.

Photochemical reaction of biphenyl in water containing nitrite or nitrate ion

Photochemical reaction of biphenyl with nitrate and nitrite in aqueous solution was investigated using two light sources, i.e., high-pressure mercury lamps fitted with a quartz glass filter (ML-Q) and a Pyrex glass filter (ML-P). Biphenyl was found to be photochemically hydroxylated and nitrated (produce nitrophenylphenols) in either nitrate and nitrite solutions, and the reaction was suppressed by excluding shorter wavelengths light than 300 nm (irradiation with ML-P) in aqueous nitrate solution. In aqueous nitrite solution, however, the reaction was easy to proceed even by irradiation with either light sources. The same tendency was also observed in the formation of mutagens which have been found to be dihydroxydinitrobiphenyls. Such wavelength characteristics for the photoreaction of biphenyl with nitrate and nitrite was correlated to the extent of the photolysis of nitrate and nitrite ions, that is, the photo-excitation of those and subsequent production of NO, NO 2 and OH radicals.

The formation of N-nitrosodibutylamine from precursors in model environmental systems

The formation of N-nitrosodibutylamine from dibutylamine and nitrite in aqueous solutions was studied in the presence of bentonite clay and humic acid. The kinetics, and effects of nitrite and amine concentration, pH, light, and temperature on the nitrosation reaction were evaluated. The N-nitrosodibutylamine yield was enhanced at low pH values, at higher temperatures and in the presence of light. The presence of humic acid was found to enhance the nitrosation while the presence of clay had the opposite effect.

Formation of mutagens by photolysis of amino acids in neutral aqueous solution containing nitrite or nitrate ion

Nine amino acids, i.e., alanine, threonine, cysteine, glutamic acid, arginine, proline, tryptophan, phenylalanine and tyrosine, were irradiated with UV light in water containing nitrite or nitrate ion under neutral conditions. The mutagenicities of the ether extracts and the residual water layers of the reaction mixtures were assayed with and without S-9 mix using Salmonella typhimurium TA98 and TA100. Three aromatic amino acids, tryptophan, phenylalanine and tyrosine, were found to give direct-acting and frameshift mutagens by irradiation in aqueous nitrite solution. Among them, the ether extract of tryptophan exhibited the strongest mutagenicity toward TA98. In the case of irradiation in aqueous nitrate solution, only the ether extract of tryptophan exhibited weak mutagenicity toward TA98 without S-9 mix. The effects of nitrite concentration, irradiation time and pH on mutagen formation from tryptophan and some characteristics of the produced mutagens were examined.

High-performance liquid chromatographic measurement of nitrite in aqueous solution by in situ formation of methyl nitrite

High-performance liquid chromatographic measurement of nitrite in aqueous solution by in situ formation of methyl nitrite

Photochemical nitrosation of phenol in aqueous nitrite solution.

Photochemical reaction of phenol with nitrite ion was investigated by ultraviolet irradiation in aqueous solution. The main product of the photochemical reaction was isolated and identified as p-nitrosophenol on the basis of spectral data and high performance liquid chromatography analysis. The production of p-nitrosophenol increased with increases in nitrite ion concentration and irradiation time. The production rate of p-nitrosophenol was enhanced under basic condition or under a nitrogen atmosphere, and was suppressed by the addition of sodium thiocyanate or under an oxygen atmospheres. These results suggested that the photo-nitrosation was caused by NO and OH radicals produced by the photolysis of nitrite ion.

Indole as a reagent for nitrite in aqueous solution

A fairly selective and sensitive spectrophotometric method for the trace determination of nitrite in aqueous solution is described. The titled ion reacts with indole in acidic medium to form a soluble pink-red product, which is measured at 530 nm. Maximum absorbance is achieved in 10 min and remains constant for about 45 min. This method is applicable to water samples containing 0–2 μg/ml with a relative error of 0.0 to–0.8%, and relative standard deviation of 0.3–0.8%, depending on the concentration level. The optimum reaction conditions affecting and related to the color reaction and interferences due to foreign ions have been studied.

Spectrophotometric Determination of Nitrite in Aqueous Solution by the Diazotization-Coupling Method with Orthanilic Acid-Resorcinol

Abstract A spectrophotometric method for the determination of nitrite is described. It relies upon the reaction of this ion with an acidified orthanilic acid solution to form a diazonium ion, which is subsequently coupled with resorcinol, in alkaline medium, to form immediately a yellow-colored stable water-soluble and intense azo dye having maximum absorption at 426 nm. The linear absorbance plot with concentration indicates that Beer's law is obeyed over the range of 1-12 μg of nitrite in a final volume of 10ml, with a molar absorptivity of 38.7 × 1031 mol−1cm−1, sensitivity index of 0.0012μgcm−3, relative error of –0.5 to +0.2% and relative standard deviation of 0.43-3.5%, depending on the concentration level. The optimum conditions affecting and related to the color reaction and interference due to foreign ions have been studied.

The S,S-acetal to carbonyl transformation using the soft NO+or Cl+species

A series of S,S-acetals (spiro-1,3-dithiolanes, 1,3-dithiolanes, and S,S-dibenzyl acetals) have been converted into the corresponding carbonyl compounds by sodium nitrite in aqueous solution (NO+, H2ONO+, CINO) or with t-butyl hypochlorite (Cl+) in anhydrous CCl4. Mechanisms for these transformations are suggested, based on the Hard and Soft Acids and Bases (HSAB) principle.