Nitrite Ion In Water Samples Research Articles

Gold Nanomaterial-Based Microfluidic Paper Analytical Device for Simultaneous Quantification of Gram-Negative Bacteria and Nitrite Ions in Water Samples.

This study presents a rapid microfluidic paper-based analytical device (μPAD) capable of simultaneously monitoring Gram-negative bacteria and nitrite ions (NO2-) for water quality monitoring. We utilize gold nanoparticles (AuNPs) functionalized with polymyxin molecules (AuNPs@polymyxin) to cause color change due to aggregation for the detection of Gram-negative bacteria, and antiaggregation in the presence of o-phenylenediamine (OPD) for NO2- detection. In this study, Escherichia coli (E. coli) serves as the model of a Gram-negative bacterium. Using the developed μPADs, the color changes resulting from aggregation and antiaggregation reactions are measured using a smartphone application. The linear detection ranges from 5.0 × 102 to 5.0 × 105 CFU/mL (R2 = 0.9961) for E. coli and 0.20 to 2.0 μmol/L (R2 = 0.995) for NO2-. The detection limits were determined as 2.0 × 102 CFU/mL for E. coli and 0.18 μmol/L for NO2-. Notably, the newly developed assay exhibited high selectivity with no interference from Gram-positive bacteria. Additionally, we obtained acceptable recovery for monitoring E. coli and NO2- in drinking water samples with no significant difference between our method and a commercial assay by t test validation. The sensor was also employed for assessing the quality of the pond and environmental water source. Notably, this approach can also be applied to human urine samples with satisfactory accuracy. Furthermore, the assay's stability is extended due to its reliance on AuNPs rather than reagents like antibodies and enzymes, reducing costs and ensuring long-term viability. Our cost-effective μPADs therefore provide a real-time analysis of both contaminants, making them suitable for assessing water quality in resource-limited settings.

A straightforward ultrasonic-assisted synthesis of zinc sulfide for supersensitive detection of carcinogenic nitrite ions in water samples

The principle objective of the present study is to explore a rapid, low-cost, ultrasound assisted one-step synthesize of zinc sulfide (ZnS) microstructures; and employee its distinct physiochemical attributes to fabricate an electrochemical sensor. The surface physiology of the prepared ZnS were systematically analyzed using various spectroscopic techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The proposed ultrasonic energy assisted one-step synthesis protocol yields homogeneously distributed ZnS microflakes courtesy of acoustic cavitation under ultrasonic environment. Further, the prepared ZnS microflakes was employed as an effective electrocatalyst for the fabrication of nitrite sensor. ZnS modified electrode revealed excellent electrocatalytic activity, and a decent analytical performance in the concentration range of 20 nM to 1.35 mM with a low detection limit of 8.5 nM towards nitrite detection, the assay performance of the proposed nitrite sensor was in line with that of the same reported earlier. Moreover, the sensor supplied high selectivity, and excellent stability. In practice, the ZnS microflakes based nitrite sensor was applied in rapid quantification of nitrite in water samples with good accuracy.

Application of a smartphone based spectrophotometer for rapid in-field determination of nitrite and chlorine in environmental water samples.

In this paper, a low cost and portable smartphone-based spectrophotometer with the purpose of measuring trace levels of two important anions, chlorine and nitrite ions in water samples, is introduced. This home-made spectrophotometer is made of Plexiglas, equipped with two LEDs as a light source, and a piece of DVD is acted as light dispersing element. Battery of smartphone was used as its power supply and spectral analysis was performed by a free software downloadable from Google Playstore. By using this lightweight spectrophotometer, various environmental samples were analyzed for their NO2- and Cl2 content in field. Good detection limits of 5.00 × 10-2 mg L-1 and 8.60 × 10-3 mg L-1 were obtained for chlorine and nitrite, respectively. The linear range for chlorine was 1.00-4.00 mg L-1 and this range for nitrite was 0.05-1.20 mg L-1. Reproducibility as relative standard deviation for both chlorine and nitrite was better than 8.75%. In order to investigate validity of data, results were compared to standard methods of measuring chlorine and nitrite, using both spectrophotometry and commercial kits which showed no difference between results obtained. This very simple to use and inexpensive device can be used many times, so can be considered as a low-cost alternative to the detection device of commercial kits.

Magnetic solid-phase extraction and a portable photocolourimeter using a multi-colour light emitting diode for on-site determination of nitrite

In this study, a new, simple, cheap, fast method for on-site determination of trace amount of nitrite in atmospheric liquids and surface water is suggested. The proposed method is based on a combination of magnetic solid phase extraction with a designed portable photometer based on light-emitting diodes. The colour reaction of nitrite was carried out with 4-nitroaniline in acidic medium and then coupled with naphth-1-ol in alkaline medium to form an azo product. The reaction and extraction conditions (e.g., acidity for diazotization and alkalinity for naphth-1-ol coupling, and other reagent concentrations, amount of sorbent, desorption solvent type and volume, etc.) were optimized. Under the optimal conditions, the calibration graph was linear in the range of 0.01–0.3 mg L−1 with the limit of detection (LOD) of 0.0013 mg L−1. The enhancement factor was about 110. Relative standard deviations (RSDs) for the extraction of 0.03 and 0.1 mg L−1 of nitrite were obtained 2.49% and 5.34% for five replicates, respectively. The proposed method was able to analyse nitrite ion in water samples with satisfactory recovery ranged from 87% to 103%.

Bi-functional sensing capability of gold multi-pod network nanostructures towards nitrite and guanine

A green and one-step preparation of Au multi-pod network nanostructures (AuMNNSs) and their enhanced electrocatalytic and sensing properties are reported in this paper. N-[3-Trimethoxysilyl)propyl]diethylenetriamine) (TPDT) and cetyltrimethylammonium bromide (CTAB) were employed for the preparation AuMNNSs. The TPDT acts as stabilizing agent and both CTAB and TPDT act as the structure directing agents. The AuMNNSs showed the better catalytic activity towards the electrooxidation of nitrite ions and guanine when compared to conventional Au nanoparticle (AuNPs) prepared in the presence of only TPDT. These results affirm that the size and shape are the prominent factors in controlling the catalytic activity of Au nanostructures (NSs). Moreover, the amperometric sensor designed using AuMNNSs showed experimental detection limits of 0.4 and 0.1 μM for nitrite ions and guanine, respectively, with excellent selectivity and the performance of present sensor was comparable or superior over already reported results. Further, the practical applicability of the present sensor was examined by detecting nitrite ions in water samples.

Development of a Chemiluminescence Detecting System Based on FPGA

In order to detect weak chemiluminescence signal rapidly and high accurately, a chemiluminescence detection system is designed based on the core chip FPGA. The system uses a static injection mechanism as chemiluminescence reaction conduit. High-performance photodiode converts chemiluminescence signals into electrical signals replacing the traditional photomultiplier tube. It can meet the test requirements while reducing the cost of the detection system. The signal processing and storage system FPGA-based consists of A/D converter module, serial communication module, the keyboard scan control modules and memory modules. Nitrite ions in water samples are detected and the results show that in a certain concentration range the calibration curve of NO2-concentration and luminescence intensity is linear, the linear regression equation is Y = 0.4148X + 2.6508, and the correlation coefficient is R2= 0.9832. The relative standard deviation values are 2.7%(n=11).

A sensitive electrochemical sensor for rapid and selective determination of nitrite ion in water samples using modified carbon paste electrode with a newly synthesized cobalt(II)-Schiff base complex and magnetite nanospheres

In this work, a simple and sensitive electrochemical sensor was developed for determination nitrite ion in water samples by using carbon paste electrode (CPE), which is modified with magnetite nanospheres as nanostructured materials and a newly synthesized cobalt(II)-Schiff base complex. The effects of various experimental parameters on the electrochemical oxidation response of the nitrite ions were investigated and optimized. At the optimum conditions the sensor has a linear response in the 0.2–30.0μmolL−1 concentration range and a low detection limit of 1.5×10−2μmolL−1 of nitrite. The results showed that the modified electrode has higher sensitivity toward nitrite ion in comparison with unmodified carbon paste electrode (CPE) and/or its nanomaterial-modified form. Obtained results showed that the modified electrode could be successfully applied for determination of nitrite in some water real samples.

Gold nanoparticles decorated on cobalt porphyrin-modified glassy carbon electrode for the sensitive determination of nitrite ion

The present study reports the electrochemical determination of nitrite ion using citrate-gold nanoparticles (cit-AuNPs) decorated on meso-tetra(para-aminophenyl)porphyrinatocobalt(II) (Co(II)MTpAP) self-assembled glassy carbon electrode (GCE). The decoration of cit-AuNPs on Co(II)MTpAP was achieved with the aid of amine groups present on the surface of the self-assembled monolayer (SAM) of Co(II)MTpAP. The SEM image shows that the cit-AuNPs were densely packed on Co(II)MTpAP. The AuNPs decorated electrode was successfully used for the determination of nitrite ion. The cit-AuNPs decorated electrode not only shifted nitrite ion oxidation potential towards less positive potential but also greatly enhanced its current when compared to bare and Co(II)MTpAP SAM modified electrodes. The amperometric current increases linearly while increasing the concentration of nitrite ion ranging from 0.5×10−6 to 4.7×10−3M and the detection limit was found to be 60nM (S/N=3). Further, the modified electrode was successfully used to determine nitrite ion in the presence of 200-fold excess of common interferents such as Na+, NO3-, I−, K+, CO32-, Ca2+, SO42-, NH4+, Cl− and glucose. The practical application of the cit-AuNPs decorated electrode was demonstrated by determining nitrite ion in water samples.

Determination of nitrite ions using test strips based on 3-hydroxy-7,8-benzo-1,2,3,4-terahydroquinoline

RIB-Nitrite-Test and Sorbfil-Nitrite-Test strips were developed for determining nitrite ions in water samples and foodstuffs by a reaction similar to the Griess reaction. Stable and noncarcinogenic 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline was used as an azo component adsorbed in the reagent paper zone on a polymeric support or on a Sorbfil plate sealed in a transparent polymeric film. Performance characteristics were evaluated by a statistical method for visual test procedures for the detection and determination of NO2− using two different test strips. The determination limit was 0.54 and 0.09 mg/L, and the detection limit was 0.50 and 0.08 mg/L, respectively.