Nitrite Salts Research Articles

Vapor Pressures of Hydrate Melts Containing Nitrate and Nitrite Salts

Vapor Pressures of Hydrate Melts Containing Nitrate and Nitrite Salts

Three new methods for generation of bis(polyfluoroalkyl) nitroxides; reactions of nitrite salts with polyfluorodiacyl peroxides, polyfluoroalkyl iodides, and polyfluoroalkylsulphonyl bromides

Three new reactions of nitrites with polyfluorodiacyl peroxides (2), polyfluoroalkyl iodides (3), or polyfluoroalkylsulphonyl bromides (4) have been found to produce bis(polyfluoroalkyl) nitroxides (1), and their possible mechanistic paths are discussed.

Chemistry of food additives: Direct and indirect effects

Considers polysorbate 60, nitrate and nitrite salts, diethylpyrocarbonate, and chick-edema factor. From the State-of-the-Art Symposium for Chemical Educators: Chemistry of the Food Cycle.

4396439 Recovery and recycle of nitrate and nitrite salts from chloride containing quench bath solids

A method is provided for the recovery and recycle of nitrate and nitrite salts present in environmentally hazardous chloride containing quench bath solids, comprising the steps of leaching the solids with hot water to provide an aqueous leachate that depletes the hot water soluble content of the solids, clearing the resulting aqueous leachate of solids, and recycling it while hot into a fused quench bath.

Isolement de nitrobacter des eaux potables et des eaux urbaines

This study is the first step toward an optimization of the bacterial oxidation of nitrogen compounds in water plants. The goal is to develop a bacterial inoculum, which could be introduced into treatment plants and therefore improve their efficiency for ammonia removal. Nitrobacteria were isolated from sludge and sand used in sewage and drinking water treatment plants. Biomass extraction from inert material was made by means of an Ultrasonic rod. The enrichment in nitrobacteria was made by series of seedings in liquid medium containing only nitrite and mineral salts. Simultaneously the number of heterotrophic bacteria decreased due to the low organic concentration in the medium. When the nitrobacteria population was higher than the heterotrophic one, a drop of the culture was plated on petri-dishes. These dishes used the same mineral medium, added of 60/00 of agar-agar. After 2 weeks of incubation small colonies of nitrobacteria were detected under a stereoscopic magnifying glass. The colonies were collected by a sterile capillary and inoculated in the mineral medium for a check of their ability to oxidize nitrite in nitrate. The purity of the strain was verified with different organic media revealing the presence of heterotrophic contaminants. Pure strains serotypes were characterized with imunofluorescence. All the isolated bacteria were of the same serotype. Nitrobacter winogradskyi serotype agilis.

Erratum

In our “Summary of Recommendations on Nitrites,” (February 1982 BioScience 32: 92) it was stated that the NSF Committee on Nitrite arjd Alternative Curing Agents in Food recommended that the use of nitrite salts be discontinued, whereas, in fact, they recommended discontinuation of nitrate salts.

Photoinduzierte hydroxylierungsreaktionen organischer chemikalien in natürlichen Gewässern - Nitrate als potentielle OH-radikalquellen -

Organic chemicals are concentrated in natural waters, where they undergo complex reactions under the influence of solar radiation and catalyzed by substances such as humic acid as well as nitrate and nitrite salts. Nitrates are present in high concentrations in natural waters (5 – 50 mg/l). The photolysis of the nitrate ion leads to the formation of OH-radicals. In this investigation the steady-state concentration of OH-radicals in different aquatic environments is estimated (∼ 5 · 10 −16 mol/l). It depends on the amount of nitrate dissolved in the water. Under the conditions of this work the half life for a great number of organic chemicals lies in the range 80 – 400 hours (for the reaction with OH-radicals).

Nucleophilic substitution at sulphonyl sulphur part 3. Hydrolysis of substituted thiophene‐2‐sulphonyl chlorides catalysed by silver nitrate and silver nitrite salts

AbstractHydrolysis reactions of substituted thiophene‐2‐sulphonyl chlorides (5‐methyl, 5‐H, 5‐chloro, 5‐nitro) catalysed by silver nitrate and silver nitrite salts have been studied in water at 25°. Salt effects by potassium nitrate, sodium perchlorate and mercuric bromide have also been investigated. For the catalysis effected with silver nitrate, the pseudo‐first order rate constants depend on the first power of silver ion concentration, while nitrate anion is not involved in the transition state. The corresponding curved Hammett plot suggests a transition state with a partially developed sulphonylium character. With silver nitrite, the rate dependence on both silver and nitrite ion concentrations would indicate that silver is involved in the transition state as well as nitrite. Also, in this case the curved Hammett plot obtained suggests a partial positive charge on the sulphur atom in the transition state. A comparison with uncatalysed hydrolysis reactions would support a previous interpretation that thiophene‐2‐sulphonyl chlorides hydrolyze by an SN2 type mechanism which can shift toward an SN1 or an SAN process depending on the ring substituent.

The nitrite-cancer controversy

Although the use of nitrate and nitrite salts to cure meats has many historical toxicologic and economic aspects, only recently has the practice been considered potentially hazardous and possibly unnecessary. Two related animal studies have purported to demonstrate the carcinogenicity of the nitrite salt, sodium nitrite, and controversy has developed among proponents of banning nitrites as food additives, the regulatory agencies USDA and FDA, and toxicologists who give varying interpretations to the findings of the animal studies. The food safety laws are based on evidence derived from toxicological tests in animals and any human evidence of hazard. In the case of cancer-causing substances according to the Delaney amendment, the prohibition is absolute for food additives. However, nitrites are not within the legal designation of “food additives” but are considered “prior sanctioned” and the Delaney clause does not apply. On the other hand, an intentionally added substance shown conclusively to cause cancer in a valid animal study would most likely fail this safety standard and thus be subject to removal from the food supply. Thus, if it would be agreed that nitrites are carcinogenic, it would be difficult to justify their continued use in foods. It is obvious that significant regulatory decisions having tremendous economic impact and human health implications must be based on adequate scientific studies that have had peer review before implementation. Following an independent review of the validity of the animal studies by an Interagency Working Group and subsequently by a special team of pathologists, the government agencies issued a statement that there is no basis to initiate any action to remove nitrite from foods at this time. Controversies of this character formed the basis of the work of the Scientific Committee of the Food Safety Council. In their 4 years of work they laid out a detailed plan of estimating the risk offered by the ingestion of any component of foods. Using a “decision tree” approach, “safe” is interpreted to mean presenting a socially acceptable risk under expected conditions of consumption and may or may not include some form of restriction of use rather than unlimited consumption. These proposals were designed to prevent future difficult-to-resolve issues such as the nitrite-cancer controversy. Obviously, it is impossible to avoid differences of opinion about the significance of histopathologic changes in animal tissue sections. However, one could conclude that had the report of the Scientific Committee of the Food Safety Council been available and the plan followed, much of the confusion surrounding the animal toxicologic findings may have been avoided.

Death Associated with Nitrite Ingestion: Report of a Case

The tissue concentrations of nitrite and nitrate found at autopsy of a case of intentional ingestion of nitrite salts have been reported. The percentage of methemoglobin and the serum nitrite concentrations are consistent with those reported for acute overdoses. We conclude that noth nitrite and nitrate salts may be identified in tissues from persons ingesting only nitrite salts and that a significant conversion to nitrate may result from oxidation of nitrite during the conversion of heme iron to Fe3+.

ChemInform Abstract: STUDY OF INORGANIC SALTS BY STATIC AND DYNAMIC SECONDARY ION MASS SPECTROMETRY

Up to now, many works in SIMS (see [1] and Refs. 1,2,5,8,9 therein) have been devoted to the study of the various phases (oxidation state of the metal) present in an oxidized metal. We have extended this kind of study to inorganic salts in which the metalloid is in various oxidation states. Therefore, we have investigated sulfate, sulfite, nitrate and nitrite salts using static and dynamic SIMS. Our purpose was to check the usefulness of the molecular information obtained from these systems and especially to see if the oxidation state of the metalloid can be deduced from the spectra. We also looked for possible artifacts induced by the ion beam and tried to follow chemical reactions on the surface of the salts.

POTENTIATION OF THE ASCORBATE EFFECT IN CURED MEAT PIGMENT DEVELOPMENT

ABSTRACTSalts of EDTA potentiate ascorbate in accelerating development of cured meat pigment both in myoglobin model systems and in laboratory prepared sausage. Iron EDTA is more effective than Na, EDTA or CaEDTA. Although EDTA salts stabilize ascorbates in nitrite solution and in buffered myoglobin solution, in the presence of nitrite plus myoglobin EDTA salts accelerate disappearance of ascorbate. This suggests that the rate limiting step in cured meat pigment synthesis is reduction of metmyoglobin to myoglobin and that EDTA salts catalyze the ascorbate reducing agent effect.

Nitrosamine formation in corrosion‐inhibiting compositions containing nitrite salts of secondary amines

Abstract Dialkylammonium nitrite salts are used to inhibit corrosion of ferrous metals in various types of packaging. We have shown that these nitrite salts, solutions used in their preparation, and material in which they are packaged may be contaminated with the corresponding nitrosamines. This nitrosamine formation may represent a hazard for people involved in the preparation or use of dialkylammonium salts.

Possible cocarcinogenic effects of coffee constituents

ALTHOUGH the carcinogenic properties of secondary N-nitro-samines and related compounds are well established1,2, their causal relationship to human cancer remains an open question because very little is known about the degree of human exposure to them. Carcinogenic N-nitrosamines have been detected in some nitrite-preserved foodstuffs, but only at relatively low levels3,4, so the major uncertainty comes from their formation in vivo from ingested nitrite and amino compounds. Formation of N-nitrosamines in this way in the digestive tract of laboratory animals has been widely demonstrated (for typical examples, see refs 5–7) and has led to the induction of tumours characteristic of N-nitrosamines8,9. We have suggested10 that the interaction between nitrite and phenolic materials should also be considered, because the latter are major dietary constituents which usually react much more rapidly than most amino compounds with nitrous acid. Certain natural phenols may therefore inhibit N-nitrosamine formation both in foodstuffs and in the digestive tract. We report here, however, that readily oxidised phenolic compounds act as catalysts rather than inhibitors for N-nitrosamine formation from nitrite salts and secondary amines at gastric pH. This finding has important implications on the possible cocarcinogenic properties of several foodstuffs and beverages, including coffee.

Breaking of seed dormancy by catalase inhibition.

Germination of some dormant seeds is promoted by solutions of thiourea, sodium nitrite, and hydroxylamine salts. The promotions are accompanied by irreversible inhibition of catalase (EC 1.11.1.6) in extracts from the seeds. The seeds are also promoted in germination by catechol and pyrogallol solutions. These effects are recorded for lettuce (Lactuca sativa L. cv. Grand Rapids) and pigweed (Amaranthus albus L.) seeds. The results indicae that metabolically derived hydrogen peroxide, spared from decomposition by catalase inhibition, oxidizes reduced NADPH required as the oxidant in the pentose pathway of glucose use. The metabolic system for such use of H2O2 involves the enzymes, peroxidase (EC 1.11.1.7) and pyridine nucleotide quinone oxidoreductase (EC 1.6.99.2), which are present in the dormant seed prior to imbibition of water.

Promotion of Seed Germination by Nitrate, Nitrite, Hydroxylamine, and Ammonium Salts

Action and uptake of azides, nitrates, nitrites, hydroxylamines, and ammonium salts were measured on germination of Amaranthus albus, Lactuca sativa, Phleum pratense, Barbarea vulgaris, B. verna, and Setaria glauca seeds. Nitrate and nitrite reductase activities were measured in vivo for each of these kinds of seeds. Activities were measured in vitro for catalase, peroxidase, glycolate oxidase, and pyridine nucleotide quinone reductase on extracts of A. albus and L. sativa seeds before and after germination. The enzymic activities measured and the responsiveness of the haemproteins to inhibition by the several compounds indicate that nitrites, azides, and hydroxylamines promote seed germination by inhibition of H(2)O(2) decomposition by catalase. Ammonium salts showed pronounced promotive activity only for B. verna and B. vulgaris seeds, for which they served as metabolic substrates.The promotion of germination is thought to depend on coupling of peroxidase action to NADPH oxidation, which can regulate the pentose pathway of d-glucose 6-phosphate use. Pyridine nucleotide quinone reductase is the possible coupling enzyme. This enzyme and others required for the action are present in the seeds before imbibition of water.

Growth of obligate autotrophic bacteria on glucose in a continuous flow-through apparatus.

Nitrosomonas europaea, Nitrobacter agilis, Thiobacillus denitrificans, T. neapolitanus, and T. thioparus (all obligate autotrophic bacteria) have been grown in dialysis culture, on glucose salts media, in the absence of their specific inorganic energy source. Metabolic products for N. agilis grown on nitrite salts medium were identified as keto acids. Pyruvic acid inhibited this organism at 5 x 10(-5)m. Keto acids were not inhibitory for the thiobacilli grown on thiosulfate medium. However, when T. denitrificans was grown on glucose with dialysis, addition of 5 x 10(-4)m pyruvate inhibited growth. Thus, it appears pyruvate may be inhibitory for other autotrophs, as has been reported for T. thiooxidans.

Spin-orbit coupling in nitrite ion and nitrite salts

The absorption intensity of the3B1 ←1A1 transition of nitrite salts of the non-transition metals is markedly dependent on the metal counterion and is causative of the yellow-orange colors of the heavier-metal salts. It is assumed that spin-orbit coupling is responsible for this phenomenon; this assumption is investigated here using semi-empirical one-electron calculations and is validated. The subjects of covalent bonding in metal salts, charge transfer transitions in such systems and the Sj ← S0 electronic spectroscopy of nitrite salts are also investigated.

A colorimetric method for the determination of total oxides of nitrogen in cigarette smoke.

A method is described for determining the oxides of nitrogen present in tobacco smoke. Components of the vapour phase of smoke are trapped on charcoal. The trap is eluted with sodium hydroxide solution and the oxidation products of nitric oxide appear as nitrite and nitrate salts. An ion-exchange technique is used to release and purify the free acids by removing excess of alkali. They are then neutralised, made just alkaline and evaporated to dryness. The residual salts are dissolved in sulphuric acid, iron(II) sulphate is added, and the absorbance of the pink complex is measured. The equivalent concentration of oxides of nitrogen is determined from a calibration graph obtained with nitrate standards. The method overcomes some of the problems of those reported previously, in that it determines both major products of oxidation of nitric oxide in smoke, and avoids the use of nitric oxide gas to prepare standards. Results have been compared with those obtained from separate determinations of the amounts of nitrite and nitrate formed by oxidation of the nitric oxide. All results are computed and reported as nitric oxide. The method has a coefficient of variation of 5·2 per cent.

Luminescence of Inorganic Nitrite Salts

Nitrite salts of the post-transition-series metals exhibit a long-lived luminescence centered at ∼5500 Å. This emission is characteristic of both the solid state and frozen glassy solutions. It is suggested that this emission originates in a triplet state (T1) of the system, and that, in fact, it is a phosphorescence of T1→S0 molecular type connecting with the ground singlet state (S0). It is shown that the spin–orbit coupling responsible for the enhanced intersystem crossing is introduced by the metal counterion and that such introduction is also dependent on the presence of nitrite-counterion covalency. The increased spin–orbit coupling is manifested in the following ways: (i) a decrease in the phosphorescence lifetime, τp, (ii) an increase in the relative quantum yield ratio Φp / Φf of phosphorescence to fluorescence, (iii) an increase in the T1←S0 absorptivity—which absorptivity is responsible for the yellow-orange colors of the heavy-metal nitrites.