Nitrosamine Formation Research Articles

Spatial, temporal variability and carcinogenic health risk assessment of nitrosamines in a drinking water system in China

Nitrosamines, as a class of emerging frequently detected nitrogenous disinfection byproducts (N-DBPs) in drinking water, have gained increasing attention due to their potentially high health risk. Few studies focus on the occurrence variation and carcinogenic health risk of nitrosamines in drinking water systems. Our study aimed to investigate the spatial and temporal variability of nitrosamines in a drinking water system and to conduct a carcinogenic health risk assessment. Three types of water samples, including influent water, treated water and tap water, were collected monthly during an entire year in a drinking water system utilizing a combination of chlorine dioxide and chlorine in central China, and 9 nitrosamines were measured. The nitrosamine formation potentials (FPs) in influent water were also determined. N-nitrosodimethylamine (NDMA) was the most prevalent compound and was dominant in the water samples with average concentrations ranging from 2.5 to 67.4 ng/L, followed by N-nitrosodiethylamine (NDEA) and N-nitrosopiperidine (NPIP). Nitrosamine occurrence varied monthly, and significant seasonal differences were observed in tap water (p < .05). There were decreasing mean NDMA, NDEA and NPIP concentrations from influent water to treated water to tap water, but no significant spatial variability was observed within the water distribution system (p > .05). The average and 95th percentile total lifetime cancer risks for the three main nitrosamines were 4.83 × 10−5 and 4.48 × 10−4, respectively, exceeding the negligible risk level (10−6) proposed by the USEPA. Exposure to nitrosamines in drinking water posed a higher cancer risk for children than for adults, and children aged 0.75 to 1 years suffered the highest cancer risk. These results suggest that nitrosamine occurrence in tap water varied temporally but not spatially. Exposure to drinking water nitrosamines may pose a carcinogenic risk to human health, especially to children.

Catalytic degradation of chlorpheniramine over GO-Fe3O4 in the presence of H2O2 in water: The synergistic effect of adsorption

Chlorpheniramine is a pharmaceutical widely used and found in water environments. Besides hormone disruption and adverse environmental effects, chlorpheniramine forms carcinogenic nitrosamines during disinfection. We have demonstrated previously the efficient adsorption of chlorpheniramine from aqueous solution onto graphene oxide-magnetite composite (GO-Fe3O4). The present study focused on the elimination of chlorpheniramine and the formation of nitrosamine byproducts during reaction with H2O2 over GO-Fe3O4 catalyst. The effects of the morphology of GO-Fe3O4 in terms of iron fraction, pH, concentrations of H2O2 and organic matters on chlorpheniramine removal in the GO-Fe3O4-H2O2 system were investigated. Chlorpheniramine was efficiently removed at pH 9 when GO-Fe3O4 had a higher micropore volume and surface area. Kinetics study showed that both oxidation (k = 5.1(±0.2) × 10−3 (mg g−1)−1 min−1) and adsorption reactions (k = 2.7(±0.1) × 10−3 (mg g−1)−1 min−1) fitted well with the second-order kinetics model. The adsorption sites on the GO-Fe3O4 surface could be different from those involved during catalytic oxidation. Chlorpheniramine removal decreased by 44.9% in the 5th cycle without regeneration due to the structural fracture of GO-Fe3O4. A tentative pathway of chlorpheniramine degradation and nitrosamine formation by GO-Fe3O4-H2O2 was proposed. GO-Fe3O4 was an adsorbent and effective catalyst in chlorpheniramine degradation by H2O2 that exhibited limited nitrosamine formation at moderate reaction time.

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.

Volatile N-nitrosamine, residual nitrite, and ascorbic acid levels in sausages during storage

Introduction. The increasing global consumption of processed meat products has led to certain concerns. For instance, processed meat products are known to contain carcinogen precursor compounds, thus creating the risk of chronic diseases. The present study was performed to estimate the food safety status of processed meat products available in Iran and evaluate the related effective factors.&#x0D; Study objects and methods. 140 samples of seven most popular commercial types of cooked sausages were obtained from four major meat factories (A, B, C and D) in 140 samples were collected from seven most popular commercial types of cooked sausages as follows: beef salami 90%, chicken salami 90%, dry cured sausage 70%, dry cured salami 60%, beef sausages 55%, chicken sausages 55% and Frankfurt sausage 40% (n = 5) from four major meat factories (A, B, C and D) in Tehran. The samples were screened for residual nitrite, ascorbic acid, and nitrosamine contents on days 0, 7, 14, 21, and 28. The results indicated that products from meat factory B had lower residual nitrite content in the samples with high content of meat. Beef salami (90% of meat) and Frankfurt sausage (40% of meat) contained the lowest and highest amounts of residual nitrite on day 0 – 73.99 and 177.42 mg of nitrite per 1 kg of meat, respectively.&#x0D; Results and discussion. Beef salami contained 90% of meat, chicken salami – 90%, dry cured sausage –70%, dry cured salami – 60%, beef sausages – 55%, chicken sausages – 55%, and Frankfurt sausage – 40% (n = 5). Nitrite reduction rates in sausages with a smaller diameter, e.g. Frankfurt sausage, were significantly lower (P &lt; 0.05), compared to salami samples. The difference can be explained by the shorter cooking time. Nitrosamine formation increased during refrigerated storage; however, it was not significant in all samples. During refrigerated storage, nitrosamine formation depended on the level of added nitrite, the amount of residual nitrite, ascorbic acid, pH, and cooking temperature. Ascorbic acid content decreased significantly (P &lt; 0.05) during refrigerated storage.&#x0D; Conclusion. The findings demonstrate significant correlation between the meat content, cooking time, nitrite content, and nitrosamine formation.

Simultaneous preparation of N2 and CO2 from water nitrates for δ15N and δ18O analysis on the example of the Zemborzycki Reservoir studies

Nitrates are bioavailable compounds, which are necessary for every living organisms. However, their excess could be harmful, because it could lead to, i.e., methemoglobinemia, formation of carcinogenic nitrosamines and reservoir eutrophication. Isotopic analysis of δ15N and δ18O in nitrates allows to distinguish their different sources. To simplify the way of nitrate source monitoring, we developed a less complex and cheap “off-line” method for nitrate isotopic analysis, in which we obtain both gases required for isotopic analysis of NO3−, N2 for δ15N and CO2 for δ18O measurements, in one procedure. The developed method is based on simultaneous conversion of AgNO3 (mixed with C and placed into PtIr boat) to N2 and CO2 in a glass vacuum apparatus. A small amount of sample (8 mg of AgNO3) required for this procedure and a good reproducibility of the isotopic analysis (better than 0.3‰ for δ18O and 1‰ for δ15N) make this method a useful tool for environmental research.Using the developed method, we analyzed the isotopic composition of N and O in nitrates in the Zemborzycki Reservoir near Lublin (Poland), in 2015. The results indicate a large variation of δ15N (from −1.4 to +37.7‰) and δ18O (from +5.5 to +25.9‰) values in NO3− ions, while the concentration of NO3− varied from 0.2 to 15.3 mg/dm3. These preliminary results suggest that nitrate fertilizers probably are the main source of NO3− pollution. Our study points out the input of manure and/or sewage to the analyzed reservoir in the subsequent periods of sample collection.

Fast, Simple, Novel and Economical Method for Ultra Trace Determination of Nine Nitrosamines in Sausage by Gas Chromatography-Flameionization Detec- tor and Ascorbic Acid and Sodium Nitrite Effect on Nitrosamine Formation

Fast, Simple, Novel and Economical Method for Ultra Trace Determination of Nine Nitrosamines in Sausage by Gas Chromatography-Flameionization Detec- tor and Ascorbic Acid and Sodium Nitrite Effect on Nitrosamine Formation

A Comparative Study on the Formation of Nitrosamines of Ethanolamines

A Comparative Study on the Formation of Nitrosamines of Ethanolamines

Evaluation of bus driver exposure to nitrogen dioxide levels during working hours

Nitrogen dioxide (NO2) is a harmful gas with impacts on human health. Human exposure to this pollutant causes an inflammatory response of the respiratory system and increased susceptibility to pulmonary infections. NO2 also promotes the formation of nitrosamines, some of which are potentially carcinogenic. Bus drivers are chronically exposed to potentially high levels of NO2 during their working hours. The objective of this study was to compare the NO2 exposure of urban bus drivers (target group) with that of office workers (control group) during working hours. This is an observational study of a population comprising 59 people, of which 30 were bus drivers (50.8%) and 29 were administrative workers (49.2%). All participants used a passive NO2 sampler that was only exposed while the participant was working. The data were collected over three-week sampling campaigns, one in winter (from June 28, 2017, to July 20, 2017) and the other in summer (from January 3, 2018, to January 24, 2018), in Caxias do Sul, Brazil. For control purposes, NO2 levels were also measured at three different city locations, one directly affected by traffic emissions (traffic station), the second far from these emissions (background station), and the third in the bus parking garage. In general, the results showed that the exposure of bus drivers to NO2 was significantly higher than that of administrative workers P < 0.001), with differences close to 75%. In winter, normally the NO2 values are higher than the summer values. These results also suggest that, assuming that NO2 is a good indicator of the presence of other pollutants of anthropogenic origin, both drivers and passengers may be exposed to unsafe concentration levels of pollutants present inside buses. Therefore, this type of study should be continued and expanded upon.

Nitrosamine formation in a semi-dry fermented sausage: Effects of nitrite, ascorbate and starter culture and role of cooking

In this study, effects of ingoing nitrite level (0, 50, 100 and 150 mg/kg), use of sodium ascorbate, addition of starter culture (Lactobacillus plantarum GM77 + Staphylococcus xylosus GM92) and cooking level (control, medium, medium well, well done and very well done) on nitrosamine formation in heat-treated sucuk, a type of semi-dry fermented sausage, were investigated. The use of ascorbate had no significant effect on NDMA (N-Nitrosodimethylamine) and NPIP (N-Nitrosopiperidine) contents in the presence of starter culture. A higher NPYR (N- Nitrosopyrrolidine) content was detected in the group with starter culture at 150 mg/kg nitrite level in comparison to the group without starter culture. Cooking level affected all identified nitrosamines very significantly. Ingoing nitrite level × cooking level interaction was only effective on NPIP and advanced cooking levels (well done and very well done) at higher ingoing nitrite levels (100 and 150 mg/kg) resulted in significant increases in NPIP content.

Inhibitory Effect of Epigallocatechin Gallate, Epigallocatechin, and Gallic Acid on the Formation of N-Nitrosodiethylamine In Vitro.

This study investigated the inhibitory effect of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and gallic acid (GA) on the formation of N-nitrosodiethylamine (NDEA) in vitro. Results show that the three polyphenols are capable to block NDEA formation when the molar ratio of phenols to nitrite is higher than 0.8, and a more acidic environment is prone to promote the inhibitory potential of phenols. It is also found that the inhibitory effect tends to decrease in the order: EGCG, EGC, GA, which is in accordance with the order of their DPPH scavenging activity, suggesting that the inhibitory effect of polyphenols on NDEA formation may work through a free radical way. Kinetic study further revealed the three polyphenols react with nitrite at a much faster rate than diethylamine does (P < 0.05). By scavenging nitrite at a faster rate than the nitrosation of diethylamine, polyphenols at high concentration can significantly block NDEA formation. These observations may promote a possible application of polyphenol compounds to inhibit the formation of nitrosamines in food processing. PRACTICAL APPLICATION: The presence of N-nitrosamines in human diet should be an etiological risk factor for human cancers. This work may provide a useful guideline for phenolic compounds to inhibit the formation of nitrosamines in food processing, such as in the process of curing meats. Polyphenols have been proved to block NDEA formation under normal gastric juice condition, suggesting the intake of polyphenols is a potential way to prevent diseases caused by nitrite.

Nitramine and nitrosamine formation is a minor pathway in the atmospheric oxidation of methylamine: A theoretical kinetic study of the CH3NH + O2 reaction

AbstractThe atmospheric oxidation of amines proceeds via initial radical attack at C–H or N–H bonds to form carbon‐ and nitrogen‐centered radicals, respectively. It is conventionally assumed that nitrogen‐centered aminyl radicals react slowly with oxygen in the troposphere and associate predominantly with the radicals •NO and NO2• to form toxic nitrosamines and nitramines. We have used theoretical kinetic modeling techniques to study the prototypical CH3N•H + O2 reaction and have shown that it proceeds to CH2NH + HO2• under tropospheric conditions with a rate coefficient of 3.6 × 10−17 cm3 molecule−1 s−1. Although this value is low compared to the competing NOx reactions (∼10−11 cm3 molecule−1 s−1), the much higher concentration of O2 versus NOx in air makes it the dominant process in the atmospheric oxidation of methylamine for NOx concentrations below 100 ppb. The mechanism identified here is available to amines with primary, secondary, and tertiary α carbons and suggests that they may be less likely to form nitramines and nitrosamines than is currently thought.

Kinetic pattern and microbial population dynamic characterization ofEscherichia coliandSalmonella enteritidisin Frankfurter sausage: An experimental and modeling study

AbstractConcerns over the safety of nitrite and its role in the formation of nitrosamines have aroused considerable interest in developing alternative antimicrobial agents to replace nitrite. Plant‐derived antimicrobial agents could serve against food spoilage and pathogens. For the first time in this study, three semiempirical kinetic models, that is, exponential, homographic, andn‐order kinetic models were established to describe the microbiological population pattern and dynamic behavior. TheEscherichia coliandSalmonella enteritidispopulation dynamics were investigated in Frankfurter sausage as a complex food system, contained four different antimicrobial redcurrant extract (RE) concentrations (0, 0.1, 0.2, and 0.4% wt/wt) at two temperatures (4 and 25°C) during 17 days storage. Furthermore, the results were compared with a neuro‐fuzzy system. Although, all three kinetic models showed a reasonable prediction accuracy, homographic kinetic model was the best for predicting antibacterial effects of RE againstE. coli(R2= 0.94–1,= 0.93–0.99,Q‐squared = 0.80–0.89, and RMSE = 0.21–0.68) and then‐order kinetic model did the best in describing the kinetic pattern ofS. enteritidis(R2= 0.97–0.99,= 0.94–0.99,Q‐squared = 0.85–0.93, RMSE = 0.06–0.74). The increase in the RE concentration and temperature resulted in the increase of kinetic parameters of microbial population decline rate and extent for both bacteria, significantly. Furthermore, all the homographic model parameters (except of equilibrium population,p∞) and all the kinetic model parameters withnorder (except of reaction order) the synergistic effect of temperature and concentration was clear. RE at 0.4% concentration induced 0.12 log colony forming unit (CFU)/gE. coliand 0.45 log CFU/gS. enteritidisequilibrium population (p∞) at 17th day of storage at 25°C. Compared toS. enteritidis,E. coliwas more sensitive to RE concentration at both temperatures.Practical applicationsMost formulations of the meat products contain nitrite as a main ingredient to prohibit the pathogenic bacteria growth. The results of the present study showed that all the three studied kinetic models (exponential, homographic, andn‐order kinetic models) appropriately modeled theS. enteritidisandE. colipopulation dynamics. Regarding the statistical parameters,n‐order and homographic kinetic models were found to be the best models for predicting antibacterial effects of RE againstS. enteritidisandE. coli, respectively. Furthermore,E. coliwas more sensitive against RE thanS. enteritidisin Frankfurter sausage samples at 4 and 25°C during 17 days storage. With the increase in the RE concentration at the constant temperature and with the increase in temperature at the constant extract concentration, the decline rate ofE. colipopulation increased significantly (p &lt; .05), while the needed time for 50% reduction decreased; besides,S. enteritidispopulation dynamics showed the increase in the rate and extent of decline, and a decrease in the equilibrium microbial population at these conditions (p &lt; .05). No significant differences were observed between the neuro‐fuzzy system results and semiempirical kinetic models in the prediction of microbiological population dynamic. Nevertheless, the novel semiempirical models presented important biological parameters, which provided a better understanding of the systems biological state than the neuro‐fuzzy system. These results could offer new perspectives in the field of microbiology.

Removal of chlorpheniramine and variations of nitrosamine formation potentials in municipal wastewaters by adsorption onto the GO-Fe3O4.

Chlorpheniramine is a pharmaceutical pollutant and a precursor of carcinogenic nitrosamines during disinfection/oxidation. In our previous study, graphene oxide coated with magnetite (GO-Fe3O4) was capable of removing chlorpheniramine in deionized water by adsorption. This study investigated the removal of chlorpheniramine and its nitrosamine formation potentials (FPs) by adsorption onto magnetic GO-Fe3O4, with respect to the influence by using real municipal wastewaters as the background. In the results, the adsorption performances of chlorpheniramine in wastewaters decreased in the order: GO-Fe3O4 suspension > GO-Fe3O4 particles > activated carbon. Chlorpheniramine adsorptions on GO-Fe3O4 particles and activated carbon were reduced by using real wastewaters as the background, whereas chlorpheniramine adsorption on GO-Fe3O4 suspension was enhanced due to the effects of surface charge on GO-Fe3O4 and ionic strength variation in water. The fittings of adsorption isotherms indicated that the wastewater background reduced the surface heterogeneity of GO-Fe3O4 suspension and improved the adsorption performance. Appreciable removal efficiencies of NDMA and other nitrosamine FPs were observed when GO-Fe3O4 particles were added in real wastewaters. However, when chlorpheniramine was present in wastewaters, chlorpheniramine adsorption and degradation reaction simultaneously occurred on the surface of GO-Fe3O4, increasing NDMA and other nitrosamine FPs in wastewaters after GO-Fe3O4 addition for chlorpheniramine adsorption. The assumption was further demonstrated by observing the NDMA-FP increase during chlorpheniramine adsorption on GO-Fe3O4 in deionized water. GO-Fe3O4 is a potential adsorbent for chlorpheniramine removal. Nevertheless, the low treatment efficiencies at high doses limit its application for nitrosamine FP adsorptions in real wastewaters.

Carcinogenic risk of N-Nitrosamines in Shanghai Drinking Water: Indications for the Use of Ozone Pretreatment.

N-Nitrosamines are drinking water disinfection byproducts that pose a high carcinogenic risk. We hypothesized that raw water treatment processes influence the types and concentrations of nitrosamines in drinking water, thereby posing differential health risks. We compared the finished water of two water treatment plants (WTP-A, WTP-B) serving Shanghai, China. Both plants use the Qingcaosha reservoir as a water source to generate drinking water with conventional but distinct treatment processes, namely preoxidation with sodium hypochlorite (WTP-A) vs ozone (WTP-B). Average nitrosamine concentrations, especially that of the probable human carcinogen (2A) N-nitrosodimethylamine, were higher in finished (drinking) water from WTP-A (35.83 ng/L) than from WTP-B (5.07 ng/L). Other differences in mean nitrosamines in drinking water included N-nitrosodipropylamine (42.62 ng/L) and N-nitrosomethylethylamine (26.73 ng/L) in WTP-A in contrast to N-nitrosodiethylamine (7.26 ng/L) and N-nitrosopyrrolidine (59.12 ng/L) in WTP-B. The estimated adult cancer risk from exposure to mixed nitrosamines was 1.83 times higher from WTP-A than from WTP-B drinking water. Children exposed to nitrosamines had a significantly higher cancer risk than adults ( p < 0.05). Disease burden exceeded 106 person-years. Taken together, these data suggest that use of ozone in the preoxidation step can reduce nitrosamine formation in drinking water and thereby lower the population cancer health risk.

Nitrosamines, Their Chemistries and Effects on Health

Meat and meat products, are one of the most important parts of a healthy and balanced diet. Also meat and meat products are accepted as a source of high biological value protein, B group vitamins, minerals and different bioactive compounds. Meat and meat products should be consumed for healthy life. But manufacturing process and products as a result of wrong practices and processes can become harmful to health. Especially processed and heat treated products are the main risk group. Nitrosamines occuring during the production as a contaminant is defined as the amine derivatives containing R1R2N-N = O functional group. Nitrosamine formation can occur in meat products with false and unconscious practice and can threat public health. Nitrosamine was reported as a carcinogenic to humans by the International Agengy For Research on Cancer. In this review, it is aimed to draw attention to the formation of nitrosamines in the meat matrix and their effects on health. Keywords : Meat products, nitrosamine, carcinogenic. DOI : 10.7176/JSTR/5-4-13

Formation potential of nine nitrosamines from polyacrylamide during chloramination

Cationic polymers, which are commonly used as flocculants and coagulant aids in water and wastewater treatment, have been recently reported to promote the formation of nitrosamines. Most of the findings to date are based on poly (epichlorohydrin dimethylamine) and poly (diallyldimethylammonium chloride), while few studies have considered nitrosamines formation of polyacrylamides. In this work, the nitrosamines formation from non-ionic, anionic and cationic polyacrylamides was evaluated. Moreover, the effects of chemical structures of cationic polyacrylamides (including molecular weight, charge density, and monomers) on nitrosamines formation were investigated. The results revealed that the highest amount of nitrosamines formation was formed from cationic polyacrylamide, followed by non-ionic polyacrylamide and anionic polyacrylamide. Molecular weight and various cationic monomers showed no significant effects on nitrosamines formation, but monomers generated significantly higher amount of nitrosamines formation than cationic polyacrylamides. Nitrosamines formation increased with the increasing charge density of cationic polyacrylamides, and FTIR analysis results showed that the quaternary amine groups preferentially reacted with chloramines than with amide groups. This work shed new light on the nitrosamines formation from water and wastewater treatment polymers.

Nitrosamines in sucuk: Effects of black pepper, sodium ascorbate and cooking level

This study determined effects of different black pepper levels (5, 10 or 15 g kg−1), sodium ascorbate usage and cooking level (raw, medium, medium well and well done) on nitrosamine formation in sucuk (a kind of dry fermented sausage). Sodium ascorbate decreased residual nitrite considerably. Cooking level had a very significant effect on nitrosodimethylamine (NDMA), nitrosopyrrolidine (NPYR) and nitrosopiperidine (NPIP) contents. NPIP content increased in sucuk both with and without ascorbate, as cooking level increased. High black pepper level decreased NPIP content in both raw and well done samples. The use of 15 g kg−1 black pepper level caused an increase in both NDMA and NPYR contents in the absence of ascorbate. In contrast, the combination of ascorbate and 15 g kg−1 black pepper resulted in a decrease in NPYR.

Formation of Multiple Nitrosamines from the Ozonation of Corresponding Precursor Secondary Amines: Influencing Factors and Transformation Mechanisms

Since nitrosamine disinfection by products is highly carcinogenic, they have attracted considerable attention due to their increased presence in ambient waterways and potable water supplies. For the present study, the potential formation of nitrosamines from corresponding precursor secondary amines during ozonation was investigated. The results revealed that five nitrosamines were observed during the ozonation of their corresponding secondary amines. The molar yields initially increased and then decreased with longer contact times and higher ozone doses. These phenomena indicated that ozone not only promoted nitrosamine formation but also degraded the formed nitrosamines. High pH had a positive influence on nitrosamine formation at room temperature. Further, coexisting substances including nitrate, nitrite, humic acid, and tert-butanol inhibited the generation of nitrosamines due to hydroxyl radical (·OH) competition and scavengers, whereas in the presence of hydroxylamine, nitrosamine formation increased considerably without ozone due to its capacity for independent formation between secondary amines and hydroxylamine. Further, the generation of nitrosamines from secondary amines was primarily attributed to O3 and ·OH oxidation, which was produced through the decomposition of ozone. The transformation pathways were mainly comprised of the indirect routes between the O3/·OH intermediates. The findings of this study were helpful toward expanding the knowledge of nitrosamine formation during the corresponding precursor secondary amine ozonation process.

Electrochemical sensing of 2-methyl-4, 6-dinitrophenol by nanomagnetic core shell linked to carbon nanotube modified glassy carbon electrode

Electrochemical behavior and sensing of 2-methyl-4, 6-dinitrophenol as an herbicide has been investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). We have synthesized a cefazolin (CEF) immobilized nanomagnetic core-shell (Fe3O4@SiO2-(CH2)3-CEF) and attached it on the modified glassy carbon electrode (GCE/MWCNT) through electrostatic adsorption (GCE/MWCNT/CEF-SiO2@Fe3O4). 2-Methyl-4, 6-dinitrophenol has an oxidation peak that is related to the formation of nitrosamine from hydroxylamine species. This peak was applied for quantifying determination of 2-methyl-4, 6-dinitrophenol. The electrochemical oxidation involves two electron transfers accompanied by two protons. The electrochemical process was controlled by adsorption. The good agreement between the obtained computational studies and the experimental results has demonstrated that outer sphere electron transfer occurred on modified electrode. The new electrochemical sensor was applied to determination of 2-methyl-4, 6-dinitrophenol by SWV in the range of 1.0 × 10−10 to 1.5 × 10−7 M with a detection limit of 0.1 nM. The proposed sensor was applied for determination of 2-methyl-4, 6-dinitrophenol in water samples.

Atmospheric Oxidation of Piperazine Initiated by ·Cl: Unexpected High Nitrosamine Yield.

Chlorine radicals (·Cl) initiated amine oxidation plays an important role for the formation of carcinogenic nitrosamine in the atmosphere. Piperazine (PZ) is considered as a potential atmospheric pollutant since it is an alternative solvent to monoethanolamine (MEA), a benchmark solvent in a leading CO2 capture technology. Here, we employed quantum chemical methods and kinetics modeling to investigate ·Cl-initiated atmospheric oxidation of PZ, particularly concerning the potential of PZ to form nitrosamine compared to MEA. Results showed that the ·Cl-initiated PZ reaction exclusively leads to N-center radicals (PZ-N) that mainly react with NO to produce nitrosamine in their further reaction with O2/NO. Together with the PZ + ·OH reaction, the PZ-N yield from PZ oxidation is still lower than that of the corresponding MEA reactions. However, the nitrosamine yield of PZ is higher than the reported value for MEA when [NO] is <5 ppb, a concentration commonly encountered in a polluted urban atmosphere. The unexpected high nitrosamine yield from PZ compared to MEA results from a more favorable reaction of N-center radicals with NO compared to O2. These findings show that the yield of N-center radicals cannot directly be used as a metric for the yield of the corresponding carcinogenic nitrosamine.