Cyanide Formation in Freezer Stored Foods: Freezing of a Glycine and Nitrite Mixture.

Freezing is not always the best way to keep foods safely. Some reactions are known to be accelerated in ice. Furthermore, some other reactions that are not observed in solution are also promoted in ice. We found that the formation of nitrosamines through the reaction of an amine with a nitrite is accelerated in ice. Surprisingly, cyanide is formed through the reaction of glycine with nitrite in ice but not in solution. Amines are present in many kinds of foods. Nitrite is present in vegetables and is used as a food coloring agent and to inhibit the reproduction of Clostridium botulinum. The maximum amount of cyanide formed reaches a dangerous level, and the intake of this formed cyanide in a few tens of cubic centimeters causes some people to get headaches. These facts suggest that hazardous compounds could be generated in frozen processed foods. We report here the formation of cyanide and its possible formation pathway in ice. Finally, we propose a way to prevent cyanide formation in food under frozen conditions.

Lowest observed adverse effect level of pulmonary pathological alterations due to nitrous acid exposure in guinea pigs.

BACKGROUND: We previously demonstrated that continuous exposure to nitrous acid gas (HONO) for 4 weeks, at a concentration of 3.6 parts per million (ppm), induced pulmonary emphysema-like alterations in guinea pigs. In addition, we found that HONO affected asthma symptoms, based on the measurement of respiratory function in rats exposed to 5.8 ppm HONO. This study aimed to investigate the dose-response effects of HONO exposure on the histopathological alterations in the respiratory tract of guinea pigs to determine the lowest observed adverse effect level (LOAEL) of HONO. METHODS: We continuously exposed male Hartley guinea pigs (n = 5) to four different concentrations of HONO (0.0, 0.1, 0.4, and 1.7 ppm) for 4 weeks (24 h/day). We performed histopathological analysis by observing lung tissue samples. We examined samples from three guinea pigs in each group under a light microscope and measured the alveolar mean linear intercept (Lm) and the thickness of the bronchial smooth muscle layer. We further examined samples from two guinea pigs in each group under a scanning electron microscope (SEM) and a transmission electron microscope (TEM). RESULTS: We observed the following dose-dependent changes: pulmonary emphysema-like alterations in the centriacinar regions of alveolar ducts, significant increase in Lm in the 1.7 ppm HONO-exposure group, tendency for hyperplasia and pseudostratification of bronchial epithelial cells, and extension of the bronchial epithelial cells and smooth muscle cells in the alveolar duct regions. CONCLUSIONS: These histopathological findings suggest that the LOAEL of HONO is < 0.1 ppm.

Comparative study on water-soluble inorganic ions in PM2.5 from two distinct climate regions and air quality.

Recently, air quality has significantly improved in developed country, but that issue is of concern in emerging megacity in developing country. In this study, aerosols and their precursor gas were collected by NILU filter pack at two distinct urban sites during the winter and summer in Osaka, Japan and dry and rainy seasons in Ho Chi Minh City (HCMC), Vietnam. The aims are to investigate the contribution of water-soluble inorganic ions (WSIIs) to PM2.5, thermodynamic characterization and possible formation pathway of secondary inorganic aerosol (SIA). The PM2.5 concentration in Osaka (15.8 µg/m3) is lower than that in HCMC (23.0 µg/m3), but the concentration of WSIIs in Osaka (9.0 µg/m3) is two times higher than that in HCMC (4.1 µg/m3). Moreover, SIA including NH4+, NO3- and SO42- are major components in WSIIs accounting for 90% and 76% (in molar) in Osaka and HCMC, respectively. Thermodynamic models were used to understand the thermodynamic characterization of urban aerosols. Overall, statistical analysis results indicate that very good agreement (R2 > 0.8) was found for all species, except for nitrate aerosol in HCMC. We found that when the crustal species present at high amount, those compositions should be included in model calculation (i.e. in the HCMC situation). Finally, we analyzed the characteristics of NH4+- NO3-- SO42- system. A possible pathway to produce fine nitrate aerosol in Osaka is via the homogeneous reaction between NH3 and HNO3, while non-volatile nitrate aerosols can be formed by the heterogeneous reactions in HCMC.

Association between indoor nitrous acid, outdoor nitrogen dioxide, and asthma attacks: results of a pilot study.

The association between nitrogen dioxide (NO2) and asthma has been investigated. However, conventional NO2 assays measure nitrous acid (HONO) as NO2. In this pilot epidemiological observational study, we assessed exposure to indoor HONO and some air pollutants in pediatric asthma patients and examined possible association between exposure and asthma symptoms. Indoor HONO and nitric oxide (NO), which are primarily generated by the combustion of certain substances, were significantly associated with asthma attacks in 2010. In 2010, indoor HONO was closely correlated with indoor NO than with outdoor NO2. Conversely, in 2012, indoor HONO was closely correlated with outdoor NO2 and NO than with indoor NO2 and NO. Outdoor NO2 was significantly associated with asthma attacks in 2012. Our results highlight the need for further epidemiological studies of the association between indoor HONO and asthma symptoms using multivariate analyses to examine the role of NO2 in asthma symptoms. Abbreviations: CXCL1: the chemokine (C-X-C motif) ligand 1; EP: the entire study period; FP: the first half of study period; HONO: nitrous acid; NO: nitric oxide; NO2: nitrogen dioxide; OH radical: hydroxyl radical; SP: the second half of study period; TNF-α: tumor necrosis factor-α; US EPA: United States Environmental Protection Agency; WHO: World Health Organization.

Effects of nitrous acid exposure on baseline pulmonary resistance and Muc5ac in rats.

We examined the baseline pulmonary resistance (RLung), baseline dynamic lung compliance (Cdyn), cytokine inductions, and histological alterations in rats exposed to nitrous acid (HONO) with secondary products of nitrogen dioxide (NO2) and nitric oxide (NO) to assess its biological effects. We exposed three groups of nine male F344 rats to different doses of HONO for six weeks (24 h/day). The cumulative values of HONO concentration were measured twice. The average concentrations of nitrogen oxide for each group were 5.8 parts per million (ppm) HONO with secondary products of 0.7 ppm NO2 and 2.3 ppm NO, 4.1 ppm HONO with 0.1 ppm NO2 and 0.6 ppm NO, and a clean air control. We measured baseline RLung and baseline Cdyn using tracheal cannulation. A tracheal tube was inserted into the trachea by tracheostomy, and lung function measurements (baseline RLung and baseline Cdyn) were conducted in mechanically ventilated rats. We measured mRNA levels of Cxcl-1, TNF-α, and Muc5ac in the right lung using quantitative RT-PCR, and observed histological alterations and the alveolar mean linear intercept (Lm) on the left lung. Our results demonstrated that HONO exposure significantly increased baseline RLung, Lm and Muc5ac expression, but did not affect baseline Cdyn or expression of Cxcl-1 and TNF-α. Further, we identified bronchial smooth muscle hypertrophy, pulmonary emphysema-like alterations in the alveolar duct centriacinar regions, and increased goblet cells in HONO-exposed rats. The present results suggest that HONO (with secondary products) adversely affects respiratory function, but that these pathologies may be unrelated to inflammation.

Acceleration and Reaction Mechanism of the N-Nitrosation Reaction of Dimethylamine with Nitrite in Ice.

Some reactions (e.g., oxidation of nitrite, denitrification of ammonium) are accelerated in freeze-concentrated solution (FCS) compared to those in aqueous solution. Ice is highly intolerant to impurities, and the ice excludes those that would accelerate reactions. Here we show the acceleration of the N-nitrosation reaction of dimethylamine (DMA) with nitrite to produce N-nitrosodimethylamine (NDMA) in FCS. NDMA is a carcinogenic compound, and this reaction is potentially accelerated in frozen fish/meat. The eaction rate of the N-nitrosation reaction becomes fastest at specific pH. This means that it is a third-order reaction. Theoretical pH values of the peak in the third-order reaction are higher than the experimental one. Freeze-concentration of acidic solution causes pH decrement; however, the freeze-concentration alone could not explain the difference of pH values. The theoretical value was obtained under the assumption that no solute took part in ice. However, solutes are incorporated in ice with a small distribution coefficient of solutes into ice. This small incorporation enhanced the decrement of pH values. Using the distribution coefficient of chloride and sodium ion and assuming those of nitrite and DMA to explain the enhancement, we succeeded in estimating the distribution coefficients of nitrite: 2 × 10-3 and DMA: 3 × 10-2.

Correction to "N-Nitrosodimethylamine Formation in Metformin Drug Products by the Reaction of Dimethylamine and Atmospheric NO2".

[This corrects the article DOI: 10.1021/acs.oprd.3c00274.].

Bio-diesel Fuel Material Supply in Vietnam and Its Current and Future Potentiality with a Focus on Rubber Seed Oil.

Diesel fuel usage in Vietnam is increasing rapidly, but most of it is imported from overseas. In this study, we investigated the possibility of popularizing bio-diesel fuel (BDF) made from Vietnamese origin resources as a sustainable energy solution. The world's energy cost fluctuates significantly depending on economic or political movements, especially after the Russian invasion of Ukraine began in 2022. This caused energy prices soar, attacking the global economy in a short period and requiring a wide range of energy supply sources. We aim to promote commercial BDF production in Vietnam for future energy security and contribution to the Vietnamese economy. Eight necessary factors were investigated to choose suitable material for BDF production. The factors are as follows: 1) material with Vietnamese origin, 2) sufficient and continuous supply volume, 3) sufficient quality to run diesel engines, including common-rail diesel engines, 4) inedibility, 5) low enough freezing point, 6) ease of collection, 7) affordability, and 8) availability of valuable elements in the material. If a suitable material candidate is not stable, it may be changed over time. In this study, the focus material was rubber seed oil. Because rubber production in Vietnam is quite stable with over 900,000 ha plantation area, and there is a potentiality to collect seeds and produce about 50,000 tons of BDF annually. In addition, the quality of rubber seeds based BDF is very high, such as low enough freezing point, etc. However, most of those rubber seeds are currently not collected and used.

Acceleration of ammonium nitrite denitrification by freezing: determination of activation energy from the temperature of maximum reaction rate.

A reaction of ammonium nitrite in ice was investigated. Upon freezing, some nitrite is oxidized by dissolved oxygen and some nitrite reacts with ammonium to produce nitrogen and water in a denitrification reaction. The former reaction was accelerated only during freezing, and the latter one was accelerated even after the whole sample was frozen. The denitrification reaction proceeded at very low concentration in ice, which were conditions under which the reaction would not proceed in solution. The nitrogen production increased linearly with increasing initial concentration of ammonium nitrite. The concentration factor in the unfrozen solution in ice was estimated to be 50.6 when the initial concentration was 0.5 mmol dm(-3), as obtained from comparison of reaction rates in solution and in ice. A new method for determination of the activation energy is proposed that gives a value of 53 to 61 kJ mol(-1) for denitrification. The reaction order of the denitrification process is also determined using our method, and it is concluded to follow third-order kinetics.

Optimization of Procedure for Determining Dissolved Oxygen in Surface Water and Seawater Exploiting the UV-vis Absorption of Mn(III) Species.

We present an analytical method for dissolved oxygen based on the quantification of Mn(III) absorbance in a water sample. After Mn(II) reacts with the oxygen molecules in water, Mn(III) is formed and stabilized by hexa-metaphosphate under acidic conditions. The UV visible absorbance of Mn(III) is proportional to the oxygen concentration in the water sample. Compared to the Winkler method, the proposed method has the same accuracy (R = 0.9992 at 0 - 52 mg dm-3) but requires fewer reagents; furthermore, it does not involve titration. Interferences from nitrite and iodate were not observed. This procedure can be used to accurately and quickly determine the oxygen concentrations in different natural water sources, including seawater.

A preliminary study on humic-like substances in particulate matter in Malaysia influenced by Indonesian peatland fires.

In this paper, ambient total suspended particulates (TSP) with a focus on humic-like substances (HULIS) are characterized based on intensive ground-based field samplings collected in Malaysia during non-haze and haze periods caused by peatland fires on the Indonesian island of Sumatra. Furthermore, concentrations of water-soluble organic carbon (WSOC) and carbon content of HULIS (HULIS-C) were determined, and fluorescence spectra of the HULIS samples were recorded by excitation emission matrix (EEM) fluorescence spectroscopy. The concentrations of WSOC and HULIS-C over the entire period ranged from 4.1 to 24 and 1.3 to 18 µgC m-3, respectively. The concentrations of WSOC and HULIS-C during the peatland fire-induced strong haze periods were over 4.3 and 6.1 times higher, respectively, than the average values recorded during the non-haze periods. Even during the light haze periods, the concentrations of WSOC and HULIS-C were significantly higher than their averages during the non-haze periods. These results indicate that peatland fires induce high concentrations of WSOC, particularly HULIS-C, in ambient TSP at receptor sites. EEM fluorescence spectra identified fulvic-like fluorophores at the highest intensity level in the EEM fluorescence spectra of the haze samples. A peak at excitation/emission (Ex/Em) ≈ (290-330)/(375-425) nm is also observed at high intensity, though this peak is normally associated with marine humic-like fluorophores. It is shown that a peak at Ex/Em ≈ (290-330)/(375-425) nm is not derived from marine sources only; furthermore, peatland fires are shown to be important contributors to HULIS around this peak.

Development of a Photometric Method to Measure Molecular Oxygen in Water.

A photometric method to determine molecular oxygen in water was developed. When manganese(II) is oxidized by oxygen under alkaline conditions, the presence of polyphosphate can prevent precipitation due to a coacervate reaction. The oxidized manganese later dissolves in acid to form a pink Mn(III) species, which has a stable UV/vis spectrum. Monitoring of the oxygen concentration based on the absorbance of the pink Mn(III) species at 517 nm showed a strong correlation with both the Winkler method and an optical sensor. As a result, the present method can measure not only dissolved oxygen, but also fine bubbles oxygen in in the water sample with high reliability (0 - 26 mg dm-3, r2 = 0.9995). During this process, no significant interference from nitrite or metal ions was observed. The accuracy of the measurement was steady at high temperatures of the water samples (≤ 363 K).

Development of a selective light-emitting diode photolytic NO(2) converter for continuously measuring NO(2) in the atmosphere.

A photolytic converter of nitrogen dioxide (NO(2)) to nitric oxide (NO) using light-emitting diodes (LEDs) has been designed to measure NO(2) in the troposphere. The typical electrical power consumption of the photolytic converter (PLC) is only 44 W. The maximum conversion efficiency of NO(2) to NO of the photolytic converter is around 90%, which is higher than that of metal halides or high-pressure Xe arc lamps (up to ∼70%). The conversion efficiency of the PLC was almost constant for at least 2.5 months. The conversion efficiency of peroxyacetyl nitrate by the LED-PLC was measured to be 2.6 ± 0.1% (1σ). The interference of HONO using the PLC was experimentally estimated to be less than 3%, which is within the uncertainty of the instrument. An intercomparison of NO(2) measurements between the PLC-CLD and the laser-induced fluorescence (LIF) technique was conducted, and the NO(2) concentrations measured by the PLC-CLD method were in agreement with those obtained by the LIF technique, within the uncertainties of the instruments. Continuous observations were made on Fukue Island, a remote area. These results demonstrate the performance of the PLC for continuous ambient measurements.

Effects of nitrous acid exposure on pulmonary tissues in guinea pigs.

Many epidemiological studies on the effects of nitrogen dioxide (NO(2)) on respiratory function may have included nitrous acid (HONO) exposures in their measures, because conventional NO(2) assays detect HONO as NO(2). A few epidemiological studies and human HONO inhalation experiments have associated HONO with decrements in lung functions. However, there have been few HONO exposure experiments in animals. This study aims to develop a HONO generation system for the animal exposure experiments, and to assess the association of HONO exposure with histopathologic alterations in the respiratory tract of guinea pigs. We exposed the guinea pigs to 3.6 ppm HONO with secondary products of 0.3 ppm NO(2) and 1.6 ppm nitric oxide (NO) for 4 weeks (24 h/day). We conducted histopathologic analyses and measured specific airway resistance (sRaw) from 7 h 40 min to 8 h 30 min after the end of HONO exposure. We found pulmonary emphysema-like alterations in the alveolar duct centriacinar regions, distortion of the centriacinar regions of alveolar ducts with extension of the bronchial epithelial cells and smooth muscle cells, and expansion of bronchial epithelial cells, in the HONO exposure. These histopathologic results suggest that a high concentration of HONO with some NO(2) and NO may associate with decrements in lung functions and some respiratory symptoms. Although the increased tendency of the sRaw value was observed in the HONO exposure group, no statistically significant difference was found between the sRaw values from the HONO exposure group and the filtered air group (p = 0.06, student's t-test).

Mechanism for sonochemical reduction of Au(III) in aqueous butanol solution under Ar based on the analysis of gaseous and water-soluble products.

When an aqueous Au(III) solution containing 1-butanol was sonicated under Ar, Au(III) was reduced to Au(0) to form Au particles. This is because various reducing species are formed during sonication, but the reactivity of these species has not yet been evaluated in detail. Therefore, in this study, we analyzed the effects of Au(III) on the rates of the formation of gaseous and water-soluble compounds (CH4, C2H6, C2H4, C2H2, CO, CO2, H2, H2O2, and aldehydes), and the rate of Au(III) reduction as a function of 1-butanol concentration. The following facts were recognized: 1) for Au(III) reduction, the contribution of the radicals formed by the pyrolysis of 1-butanol was higher than that of the secondary radicals formed by the abstraction reactions of 1-butanol with ·OH, 2) ·CH3 and CO acted as reductants, 3) the contribution of ·H to Au(III) reduction was small in the presence of 1-butanol, 4) aldehydes and H2 did not act as reductants, and 5) the types of species that reduced Au(III) changed with 1-butanol concentration.

Time Series Analysis of Climate and Air Pollution Factors Associated with Atmospheric Nitrogen Dioxide Concentration in Japan.

Nitrogen dioxide (NO2) is an air pollutant discharged from combustion of human activities. Nitrous acid (HONO), measured as NO2, is thought to impact respiratory function more than NO2. HONO and NO2 have an equilibrium relationship, and their reaction is affected by climate conditions. This study was conducted to discuss the extent of HONO contained in NO2, depending on the level of urbanization. Whether climate conditions that promote HONO production enhanced the level of NO2 measured was investigated using time series analysis. Climate and outdoor air pollution data measured in April 2009-March 2017 in urban (Tokyo, Osaka, and Aichi) and rural (Yamanashi) areas in Japan were used for the analysis. Air temperature had a trend of negative associations with NO2, which might indicate the decomposition of HONO in the equilibrium between HONO and NO2. The associations of relative humidity with NO2 did not have consistent trends by prefecture: humidity only in Yamanashi was positively associated with NO2. In high relative humidity conditions, the equilibrium goes towards HONO production, which was observed in Yamanashi, suggesting the proportion of HONO in NO2 might be low/high in urban/rural areas.

Ultrasound Assisted Cascade Extraction of Oil, Vitamin E, and Saccharides from Roselle (Hibiscus Sabdariffa L.) Seeds.

Roselle seeds, a waste biomass of the roselle calyx processing industry, were utilized to recover valuable compounds of oil, vitamin E, and water-soluble saccharides. Firstly, ultrasound-assisted extraction (UAE) and conventional stirring extraction were conducted for saccharide extraction, and the advantage of UAE was confirmed. Secondly, oil, vitamin E, and saccharides extracted from Vietnamese roselle seeds by UAE were analyzed for the first time. Oil of tri-, di-, and mono-glycerides, fatty acids of linoleic-, oleic-, palmitic-, and stearic-acids, vitamin E of γ- and α-tocopherol, and saccharides of sucrose, raffinose, stachyose, etc. were identified, and the amounts of these components were compared with those in other country's roselle seeds. Thirdly, cascade extraction of oil, vitamin E, and saccharides by UAE was investigated with solvents of hexane, hexane:ethyl acetate binary solvent, and water. The results indicated that the order of using solvents was very important for high and selective extraction: the best order to recover oil (almost 100%), vitamin E (95.7%), and saccharides (86.2%) was hexane, and then water.

The chemistry of drying an aqueous solution of salts.

The fate of salts in drying aqueous solution was investigated. In the drying of acidic solutions, weak acid ions and chloride ions combine with protons and evaporate, depending on the proton concentration. In the drying of alkaline solutions, weak acid ions evaporate or remain as salts depending on the ratio of the concentrations of excess nonvolatile cations (the difference between concentrations of nonvolatile cation and nonvolatile anion) to volatile anions defined as DeltaCA. Under neutral and alkaline conditions, the fate of nitrite depends not only on DeltaCA but also on the drying speed. Nitrite is converted to N2, which is formed by reacting nitrite with ammonium (denitrification), NO and NO2, HONO and salts. In urban areas, nitrite and ammonium can appear in high concentrations in dew. HONO in the atmosphere affects the ozone concentration, but dew formation decreases the concentration of HONO. If chemical denitrification occurs, nitrogen species will decrease in the environment, and as a result, the ozone concentration could decrease. Ozone levels show an ozone depression when dew formed, and a Box model simulation showed an ozone depression by decreasing HONO levels.

Sonochemical decomposition of organic acids in aqueous solution: understanding of molecular behavior during cavitation by the analysis of a heterogeneous reaction kinetics model.

The sonochemical decomposition of a low concentration of butyric acid was performed in an aqueous solution by use of 200 kHz ultrasound to discuss the reaction kinetics and molecular behavior during cavitation. Taking into account a Langmuir-type adsorption model, we propose a heterogeneous reaction kinetics model, which is based on the local reaction zone at the interface region of the cavitation bubbles, where the adsorption and desorption of butyric acid molecules from the bulk solution occur during bubble oscillation and then the existing molecules inside the local reaction zone are finally decomposed. To confirm our proposed kinetics model, the rates of decomposition were investigated as a function of the initial concentration of butyric acids in the different pH solutions. It was confirmed that our model could be reasonably applied to explain the obtained results and the pseudo rate constant (k) and the equilibrium constant (K) were able to be calculated: k is 8.0 microM min(-1) (pH 2) and 3.5 microM min(-1) (pH 10), and K is 5.7 x 10(-3) microM(-1) (pH 2) and 8.0 x 10(-3) microM(-1) (pH 10), respectively. By the analysis of the obtained K values, it was clear that the ionized organic acid molecules are relatively difficult to accumulate at the reaction zone, because of their lower hydrophobicity compared with that of the neutral ones. The results obtained in the sonochemical decomposition of benzoic acid were also able to be analyzed with the proposed kinetics model. In addition, we proposed an opinion toward the interpretation of a Langmuir-type adsorption model which has often been applied to explain heterogeneous reaction systems.

Influence of adding salt on ultrasonic atomization in an ethanol-water solution.

Ethanol was enriched by ultrasonic atomization. Enrichment ratios were increased by adding salt to the ethanol solution. Different enrichment ratios were observed for different types of salts in a range of low ethanol concentrations. The enrichment ratio was significantly improved by adding K(2)CO(3) or (NH(4))(2)SO(4). It is concluded that this is due to enhanced interfacial adsorption of the ethanol. Addition of Na(2)CO(3) to the ethanol solution also enhanced the interfacial adsorption of the ethanol, but the effect was relatively small. Addition of NaCl to the ethanol solution did not enhance the interfacial adsorption of the ethanol.