Determination Of Nitrite Research Articles

Voltammetric sensor based on long alkyl chain tetraalkylammonium ionic liquids comprising ascorbate anion for determination of nitrite

An electrochemical sensor was fabricated utilizing ionic liquids possessing cations with long alkyl chains such as trimethyl octadecylammonium and behenyl trimethylammonium and ascorbate anion. The ionic liquids were drop-coated onto the electrode. Thin modifying layers were prepared. Cyclic voltammetric investigations revealed electrostatic interactions between the electrochemical probes and the modified surface, proving that a positive charge was established at the film surface. Hence, negatively charged species such as nitrite can be pre-concentrated on the surface of presented modified electrodes. The fabricated electrodes have been used as a voltammetric sensor for nitrite. Due to the electrostatic accumulation properties of long alkyl cation, the assay exhibits a remarkable improvement in the voltammetric response toward nitrite oxidation. The influence of pH on the electrode response was thoroughly investigated, and the mechanism of the electrode was established. The developed sensor showed a linear electrochemical response in the range 1.0–50 μM with a detection limit of 0.1 μM. The electrode revealed good storage stability, reproducibility, and anti-interference ability. The determination of nitrite performed in curing salts brought satisfactory results.Graphical abstract

Elaeocarpus Ganitrus Structured Mesoporous Hybrid Mn3+/4+ loaded Zirconia Self Assembly as a Versatile Amperometric Probe for the Electrochemical Detection of Nitrite

AbstractSelective and highly sensitive detection of nitrite is always a challenge for electrochemist for the administration of nitrite in water and food samples. In this regard nanostructured materials are crown choice. In the present investigation, we have prepared uniformly ordered hybrid Mn3+/4+ : ZrO2 nanoganitrus via hydrothermal method, characterized by XRD, BET, SEM, TEM and XPS to understand the structural and morphological features of the material and used for the electrocatalytic determination of nitrite. The preparation process resulted in the formation of nanoganitrus heterostructures with honeycomb arrangement. High surface area, ganitrus structure and hybrid Mn3+/4+ in the material was correlated to its robust electrochemical performance. Thus, prepared sensor showed highly selective and sensitive determination of nitrite with a good linear range of 250 μM to 10,000 μM with correlation coefficient of 0.998 and a sensitivity of 38.8 μAmM−1 cm−2. The limit of Detection of nitrite sensing system was 93 μM at a signal to noise ratio of 3. Also, the sensor showed prominent reproducibility, good stability, anti‐interference performance and also the prepared sensor was successfully used for the detection of nitrite in real samples.

Chitosan-derived N-doped carbon dots for fluorescent determination of nitrite and bacteria imaging

N-doped carbon dots (N-CDs) were successfully synthesized via simple one-step hydrothermal carbonization using chitosan as carbon and nitrogen sources. The obtained N-CDs contained a variety of functional groups on the NCDs surface, and exhibited excitation-independent behavior and strong blue fluorescence with a relatively higher fluorescence quantum yield (QY = 35%). It also presented excellent water solubility, resistance to pH change, high ion strength and UV irradiation. Since the fluorescence of the N-CDs could be selectively quenched by NO2–, they could act as a fluorescent sensor for the determination of NO2– in real tap water and lake water samples with a wide linear range (1–500 μM) and low detection limit (0.1 μM). They could also be used for bacterial imaging as multicolor fluorescent probes. The results indicated that N-CDs could be a promising candidate material for biomedical applications.

Simultaneous Determination of Nitrite and Azide Ions in Valsartan.

This study aimed to establish an ion chromatography for the simultaneous determination of nitrite and azide ions in valsartan. Dionex IonpacAG18 (4×50mm2) and Dionex IonpacAS18 (4×250mm2) were used as the 2D guard column and analytical column, respectively. Dionex AMGTMC18 (4×30mm2) was used as a 1D pre-separation column and Dionex UTAC-ULP1 as the concentration column. KOH solution generated by an online eluent generator (EG) was used as the 2D mobile phase, and gradient elution was performed at 1mL/min. Water and acetonitrile were used as 1D mobile phase, and gradient elution was performed at 0.5mL/min. Suppressed conductivity detector (suppressor, ASRS 300 4mm) was used for detection. The column temperature was 30°C, while that of the detector was 35°C. This method showed satisfactory reproducibility and recovery. The linear range and the correlation coefficient for both nitrite and azide ions were 0.01-0.2mg/L and 0.9998, respectively. However, the recovery rate was 85-115% for nitrite and 90-110% for azide ions. This method was suitable for the simultaneous determination of nitrite and azide ions in valsartan and other sartan drugs.

Short-Term Impact of Two Kinds of Vegetables to Exogenous Total Nitrate and Nitrite Intake: Is Antibacterial Mouthwash Influential?

Background:Nitrate is a compound with adverse effects on human health that can exist also in vegetables. This study aimed to determine the intake of total nitrate/nitrite from lettuce and carrot as high and low nitrate content, respectively. Moreover, the effect of chlorhexidine mouthwash on the elimination of the nitrite level in saliva and urine was surveyed.Methods:This study was designed as a crossover based on the randomized selection method. Thirty-nine participants were divided into two groups; the lettuce and carrot juice consumers (control group). The case group was consumed these two vegetables, while they used antibacterial mouthwash. The background of nitrate/nitrite of the participants was determined before exposure. The intake of total nitrate and nitrite via lettuce and carrot juice consumption was investigated. The Griess colorimetric reaction was used for nitrate and nitrite determination in samples.Results:Total nitrate concentrations in case and control groups were detected 0.79 and 0.78 mM in saliva and 1.78 and 1.38 mM in urine after lettuce consumption, respectively. However, it was determined 1.55 and 2.43 mM in saliva and 2.92 and 3.04 mM in urine after carrot ingestion. Salivary nitrite concentration 0.53 mM was decreased to 0.45 mM after antibacterial mouthwash application (P-value <0.05).Conclusions:This study indicated that the intake of total nitrate/nitrite via leafy vegetables was higher than rooty ones. The chlorhexidine mouthwash is an appropriate recommendation to reduce the nitrite concentration in the human body for preventing the probable side effects of nitrate metabolites such as N-nitrosamines forming.

Preparation of Mixed-Valent Manganese-Vanadium Oxide and AU Nanoparticle Modified Graphene Oxide Nanosheets Electrodes for the Simultaneous Determination of Hydrazine and Nitrite

Preparation of Mixed-Valent Manganese-Vanadium Oxide and AU Nanoparticle Modified Graphene Oxide Nanosheets Electrodes for the Simultaneous Determination of Hydrazine and Nitrite

Possibilities of using composite electrode based on carbon nanotubes for determination of nitrite in aqueous and biological media

Определение метаболитов оксида азота, в частности нитрита, в биологических средах является актуальной задачей для оценки состояния пациентов. Весьма перспективными для определения нитрита в биологических средах являются электрохимические методы. В настоящей работе показаны возможности применения композитного пастового электрода на основе многостенных углеродных нанотрубок и полиметиленового голубого (МУНТ-ПЭ/ПМГ) для вольтамперометрического определения нитрита в водных и биологических средах. Показано, что на немодифицированном пастовом электроде на основе МУНТ процесс окисления нитрита протекает со значительным перенапряжением; на вольтамперной кривой наблюдается широкий пик тока окисления с максимумом при потенциале +1000 мВ. В то же время модифицирование МУНТ-ПЭ полиметиленовым голубым приводит к снижению перенапряжения реакции окисления нитрита; потенциал в максимуме окисления - +800 мВ, на кривой наблюдается выраженный пик. В диапазоне концентраций нитрита в растворе от 2·10-5 М до 5·10-3 М наблюдается линейная зависимость величины тока окисления нитрита от его концентрации. Проведены модельные исследования композитного электрода МУНТ-ПЭ/ПМГ в плазме крови в присутствии нитрита. Сравнение вольтамперных кривых, полученных в водных растворах и в плазме крови, показало, что протекание процесса окисления нитрита в плазме крови соответствует протеканию процесса в водной среде – потенциал и высота пика окисления практически совпадают. Результаты модельных исследований в плазме крови позволяют сделать вывод о том, что электрод МУНТ-ПЭ/ПМГ потенциально может быть использован для определения нитрита в образцах плазмы крови пациентов.

Two-dimensional conductive phthalocyanine-based metal-organic frameworks for electrochemical nitrite sensing.

2D nickel phthalocyanine based MOFs (NiPc-MOFs) with excellent conductivity were synthesized through a solvothermal approach. Benefiting from excellent conductivity and a large surface area, 2D NiPc-MOF nanosheets present excellent electrocatalytic activity for nitrite sensing, with an ultra-wide linear concentration from 0.01 mM to 11 500 mM and a low detection limit of 2.3 μM, better than most reported electrochemical nitrite sensors. Significantly, this work reports the synthesis of 2D conductive NiPc-MOFs and develops them as electrochemical biosensors for non-enzymatic nitrite determination for the first time.

Silver-miang nanocomposites: A green, rapid and simple approach for selective determination of nitrite in water and meat samples

A green, rapid, simple and reliable procedure was developed for nitrite determination using silver-miang nanocomposites as colorimetric agents and camera phone as a detector. The crude water extracts of miang (Camellia sinensis var. assamica) were adopted as natural reagents in a rapid one-pot microwave synthesis of the nanocomposites. The extracts’ phytochemical contents were studied and the synthesis conditions were optimized. The yielded nanocomposites were characterized by UV–vis and FT-IR spectroscopies, powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction and thermogravimetry, and proved to be reliable colorimetric agents and selective for nitrite. The underlying reactions were investigated. The linear calibration plots could be established based on the ratiometric R/G parameters over 2.0–10 mg∙L−1 nitrite concentration range with satisfying detection limits (0.12–0.62 mg∙L−1). In practice, the procedure was validated and applied with water and commercialized meat samples. The long storage time of miang (>5 years) was also evaluated, manifesting viability and reliability in views of both the nanocomposites synthesis and the nitrite determination performance.

Ionic chromatographic determination of iodides, nitrites and bivalent iron in water with amperometric detector

Introduction. The majority of ionic chromatographic methods approved in our country for assessing the quality and chemical safety of water for the content of controlled anions and cations are developed using conductometry. However, quantitative determination of micro concentrations of cations and anions in drinking water and other water bodies against the background of macro concentrations of other components due to their interfering influence by the method of conductometric ion-chromatographic analysis is not possible. Material and methods. The tap water in Nothern East Administrative district of Moscow was used. The “Stayer” ion chromatograph with amperometric and conductometric detectors and separating columns was used. The column Phenomenex Star Ion A-300 100/4.6 was used for the determination of iodide. The column Shodex IC SI-52 4E 250/4, 6 was used for the determination of nitrite. The column Shodex IC YS-50 150/4.6 was used for the determination of bivalent iron. Results. Chromatograms of ion chromatographic analysis with amperometric and conductometric detections of tap water with different contents of target ions are presented. It is shown that it is impossible to determine the target components using the standard method with conductometric detection. The content of accompanying ions (chlorides, nitrates, and sulfates), exceeding the concentration of nitrite and iodide by tens of thousands of times, was not prevented by the determination. Discussion. The high efficiency of the proposed method for determining iodides, nitrites, and bivalent iron is provided due to their anode discharge in the electrochemical cell of the detector. Interfering components (chloride, nitrate, phosphate, and sulfate) neither participate in the anodic oxidation process and nor generate an electrical signal; that allows determining micro concentration of nitrite and iodide ions and bivalent iron in virtually any aqueous system containing an excess of chlorides, nitrates, sulfates. Conclusion. Authors proposed a highly sensitive ion - chromatographic amperometric determination of iodide, nitrite ions and bivalent iron in water and other water bodies. It allows eliminating the interfering influence of macro concentrations of accompanying components. The determination is performed by direct insertion of the sample into the chromatographic system.

Electrochemical Sensing Platform Based on Lotus Stem‐derived Porous Carbon for the Simultaneous Determination of Hydroquinone, Catechol and Nitrite

AbstractA simple and highly selective electrochemical sensor based on carbonized lotus stem (CLS) was developed for the simultaneous determination of hydroquinone (HQ), catechol (CC), and nitrite (NT) by using cyclic voltammetry (CV) and amperometry (AMP) methods. The CLS was characterized by the methods including field emission scanning electron microscopy (FE‐SEM), Raman spectrum, FT‐IR spectrum and X‐ray diffraction (XRD). Brunauer‐Emmett‐Teller (BET) method was used to evaluate the pore structure and surface area of CLS. The oxidation peaks for HQ (116.2 mV), CC (220.1 mV), and NT (818.9 mV) were well separated under optimized conditions, which improved their simultaneous determination. The CLS modified electrode showed a good linear range between 1.0×10 −6 to 7.0×10 −4 M for HQ, and the detection limit was calculated as 0.15 μM. For CC the linear relationship was 1.0×10 −6 to 3.0×10 −3 M with the detection limit of 0.11 μM. For NT the linear relationship was 5.0×10 −7 to 4.0×10 −3 M with the detection limit of 0.09 μM. The results indicated that the intrinsic structure of natural biomass can be expected to design porous carbon for electrochemical sensors.

Simultaneous determination of nitrate, nitrite and bromate by capillary zone electrophoresis in tea infusions grown in the Black Sea region of Turkey

AbstractA quick method for the simultaneous determination of nitrate, nitrite and bromate ions in tea infusions using capillary zone electrophoresis was developed. A three‐factor full factorial design was applied for the determination of optimal conditions. Prior to the full factorial analysis, a number of experiments were conducted. A 50 mM phosphate buffer solution with pH 3.5 was selected. A capillary temperature of 40 °C, −20 kV applied voltage, 61.5 cm total capillary length (53.5 cm effective length) with 50 μm i.d., and 50 mbar injection pressure for 30 s were used. The limits of detection for nitrate, nitrite, and bromate were 0.60, 0.99, and 2.14 mg/L, respectively. The anions could be detected by the method with good resolution within 7 min with average spike recovery ranging between 91.6 and 105.5% (n = 3).

New application for TiO2 P25 photocatalyst: A case study of photoelectrochemical sensing of nitrite ions

Developing photoelectrochemical (PEC) sensors based on photocatalytic materials has recently attracted great interest as an emerging technology for environmental monitoring. TiO2 P25 is a well-known highly active photocatalyst, cheap, and produced commercially on a large scale. In the current work, a practical and durable TiO2-based PEC sensor has been fabricated by immobilizing TiO2 P25 nanoparticles at disposable screen-printed carbon substrates using drop-casting method. The fabricated PEC sensor has been applied for the anodic-detection and determination of nitrite (NO2−) ions under UV(A) light (LED, 365 nm) using chronoamperometry (CA) and differential pulse voltammetry (DPV). Linear calibration curves were obtained between the photocurrent responses and the concentrations of NO2− ions in the ranges of 0.1–5.0 and 0.5–10 mg L−1 for CA and DPV, respectively. Surprisingly, the detection limits (sensitivities) of the fabricated sensor towards NO2− ions under light were enhanced by a factor of 4.75 (4.1) and 8.3 (37.4) for CA and DPV, respectively, in comparsion with those measured in the dark. It is found that the photo-excitation of TiO2 facilitates the photooxidation of NO2− ions via the photo-generated holes whereas the photogenerated electrons contribute to the enhanced photocurrent and consequently the enhanced detection limit and sensitivity. The fabricated TiO2-based PEC sensor exhibits a good stability, durability, and satisfying selectivity for NO2− ions determination. These results indicate that the TiO2-based PEC sensor fabricated by utilizing cheap and commercially available components has great potential for being transferred from lab-to-factory.

Synergistic integration of Au nanoparticles, Co-MOF and MWCNT as biosensors for sensitive detection of low-concentration nitrite

Nitrite has been widely existed in food and natural environment systems. To protect the environmental safety and human health, non-enzymatic nitrite sensor with reasonable linear response range, low detection limit (LOD) and excellent storage stability are highly desirable. Herein, we designed a hierarchical structure including the multiwalled carbon nanotube (MWCNT) as substrates, Co-based metal-organic framework (Co-MOF) and high-dispersed small Au nanoparticles (AuNPs) (denoted as AuNPs/Co-MOF/MWCNT). Small Co-MOF nanoplates were firstly grown on the surface of MWCNT, and then provides abundant adsorption sites for catching Au ions. The Co-MOF plays a crucial role in controlling the growth and dispersion of AuNPs, and limits particle growth during the reduction process. Combining MWCNT with Co-MOF can significantly improve the electron transport capability of Co-MOF. On the other hand, small and uniform AuNPs distributed on Co-MOF can reduce the operating voltage and significantly enhance their catalytic activity for nitrite oxidation. Owing to the intriguing synergy between the components, the obtained nitrite sensor device exhibits a broad linear response range from 1 to 1000 µM and a LOD of 0.4 µM (S/N = 3) with a fast response balance (the response time ≈ 3.5 s) at a voltage of 0.72 V. Moreover, this sensor remains 94.5% of their initial response after 20 days of storage at room temperature in air. These results suggested that the AuNPs/Co-MOF/MWCNT nanocomposite has a good application prospect in the amperometric determination of nitrite.

Development of an innovative nitrite sensing platform based on the construction of carbon-layer-coated In2O3 porous tubes

Excessive uptake of nitrite has been proven to be harmful for human health and ecological systems, so it is vital to develop a reliable methodology for nitrite analysis. In this work, we have synthesized innovative carbon-layer-coated In2O3 porous tubes (C@In2O3 PTs) to electrochemically detect nitrite in industrial wastewater samples. C@In2O3 PTs were prepared through the thermal decomposition of metal organic frameworks (MOFs, MIL-68-In) based on the two-step synthetic processes. The obtained C@In2O3 PTs displayed obviously increased catalytic activity to the electrochemical oxidation of nitrite, which benefited from the enhanced surface area and electron transfer based on the porous and hollow structure, and the maximized synergistic effect due to the intimate contact between In2O3 core and carbon layer. Thus, the sensitive determination of nitrite with a detection limit of 0.08 μM was realized, which was promising for sensitive determination of nitrite in the environmental analysis and food industry.

Evolution of novel rGO/ZrHCF composite and utility in electrocatalysis towards nanomolar detection of sodium nitrite and ferulic acid

Novel composite of reduced graphene oxide/zirconium hexacyanoferrate (rGO/ZrHCF) was fabricated via electrochemical deposition and used as a sensor for detecting sodium nitrite and ferulic acid. The sensor was thoroughly characterized using scanning electron microscope, DRS-UV, attenuated total reflection IR spectroscopy as well as atomic force microscopy. The rGO/ZrHCF exhibited cube-like morphology of ZrHCF on multilayered rGO sheets. Electrochemical characterization was carried out using cyclic voltammetry and square wave voltammetry for the detection of ferulic acid and sodium nitrite. Ferulic acid and sodium nitrite are used as food additives and the overdose of either of them can result in various physiological ailments and necessitates their detection. The proposed sensor could detect both sodium nitrite and ferulic acid at nanomolar levels exhibiting linearity in the range of 1.14 to 13.77 nM and 3.23 to 41.98 nM, respectively. The corresponding limit of detection was 0.38 nM and 1.39 nM. The rGO/ZrHCF-modified electrode was checked for real sample analysis by carrying out determination of sodium nitrite and ferulic acid in water and milk samples and the recovery percentages were found to be in between 96.15 and 99.80. The sensor exhibited long-term stability and reproducibility.

Gold nanoparticles decorated bimetallic CuNi-based hollow nanoarchitecture for theenhancement ofelectrochemical sensing performance of nitrite.

Gold nanoparticles (AuNPs) decorated bimetallic CuNi-based hollow nanoarchitecture (CNHN) are reported for the first timeas a nonenzymatic sensor for the quantification of nitrite in neutral solution . The CNHN was prepared via a convenient calcining routine using the bimetallic CuNi-MOFs as a coprecursor. The unique chemical structure of hollow CNHN with high specific surface area and abundant terminal amino groups effectively avoid the aggregation of AuNPs and facilitate the subsequent adsorption of nitrite. The Au/CNHN exhibited high electrocatalytic activity towards nitrite oxidation due to the synergetic catalytic effect of AuNPs and CNHN. Chronoamperometric detection of nitrite at the Au/CNHN/GCE achieved a lower linear calibration range of0.05 to 1.15mM, with an LOD of 0.017μM compared with previous reports. Theproposed method obtained satisfactory recoveries for nitrite determination in practical applications, which was verified by UV-Vis spectrophotometry. Theprepared sensor based on Au/CNHN featured favorable selectivity and stability, which providesa promising approach for real sample analysis. Graphical abstract.

Ultrasensitive determination of nitrite based on electrochemical platform of AuNPs deposited on PDDA-modified MXene nanosheets

An ultrasensitive and high-performance electrochemical nitrite sensing platform based on gold nanoparticles deposited on poly (dimethyl diallyl ammonium chloride)-decorated MXene (Ti3C2Tx) (AuNPs/Ti3C2Tx-PDDA) was constructed. AuNPs/Ti3C2Tx-PDDA on the surface of electrode displayed synergetic catalytic effect for oxidizing NO2‾ originating from especially catalytic activity of AuNPs, large area and excellent conductivity of Ti3C2Tx, as well as electrostatic interaction of PDDA. The amperometry technique was employed for quantitative determination of nitrite, in which the AuNPs/Ti3C2Tx-PDDA/GCE sensing platform showed outstanding linear relationship in 0.1–2490 μM and 2490–13490 μM for nitrite, meanwhile the detection limit of 0.059 μM. Besides, the prepared sensor possessed high sensitivity of 250 μA mM−1 cm−2 yet excellent selectivity, stability and reproducibility. Furthermore, this platform also exhibited satisfactory feasibility of nitrite sensing in running water and ham sausage sample. This work would broaden a facile approach to construct high sensitivity electrochemical sensing platform via two-dimension materials and its nanocomposites.

Methyl jasmonate delays the latency to anoxic convulsions by normalizing the brain levels of oxidative stress biomarkers and serum corticosterone contents in mice with repeated anoxic stress.

Repeated exposure to anoxic stress damages the brain through cortisol-mediated increases in oxidative stress and cellular-antioxidants depletion. Thus, compounds with antioxidant property might confer protection against anoxic stress-induced brain injuries. In this study, we further examined the protective effect of methyl jasmonate (MJ), a potent anti-stress agent against anoxic stress-induced convulsions in mice. Thirty-six male Swiss mice randomized into six groups (n=6) were given MJ (25, 50 and 100mg/kg, i.p.) or vehicle (10mL/kg, i.p.) 30min before 15min daily exposure to anoxic stress for 7days. The latency(s) to anoxic convulsion was recorded on day 7. The blood glucose and serum corticosterone levels were measured afterwards. The brains were also processed for the determination of malondialdehyde, nitrite, and glutathione levels. Methyl jasmonate (MJ) delayed the latency to anoxic convulsion and reduced the blood glucose and serum corticosterone levels. The increased malondialdehyde and nitrite contents accompanied by decreased glutathione concentrations in mice with anoxic stress were significantly attenuated by MJ. These findings further showed that MJ possesses anti-stress property via mechanisms relating to the reduction of serum contents of corticosterone and normalization of brain biomarker levels of oxidative stress in mice with anoxic stress.

Validation of an Analytical Method for Nitrite and Nitrate Determination in Meat Foods for Infants by Ion Chromatography with Conductivity Detection.

Nitrate and nitrite as sodium or potassium salts are usually added to meat products to develop the characteristic flavor, to inhibit the growth of microorganisms (particularly Clostridium botulinum), and effectively control rancidity by inhibiting lipid oxidation. However, both nitrate and nitrite ions need to be monitored for ensuring the quality and safety of cured meats. In this work, for the first time the content of nitrite and nitrate ions in homogenized meat samples of baby foods was determined by a validated method based on ion chromatography (IC) coupled with conductivity detection. Recoveries of nitrate and nitrite ions in meat samples were not lower than 84 ± 6%. The detection limits of nitrate and nitrite were 0.08 mg L−1 and 0.13 mg L−1, respectively. Five commercial samples of homogenized meat, namely lamb, rabbit, chicken, veal, and beef, for infant feeding were investigated; while nitrite content was below the detection limit, nitrate ranged from 10.7 to 21.0 mg kg−1. The results indicated that nitrate contents were below the European (EU) fixed value of 200 mg kg−1, and an acceptable daily intake of 3.7 mg kg−1 was estimated.