Amperometric Detection Of Nitrite Research Articles

Electrochemical preparation of gold nanoparticles on ferrocenyl-dendrimer film modified electrodes and their application for the electrocatalytic oxidation and amperometric detection of nitrite

This work describes the preparation of sensors for electrochemical determination of nitrite, based on modified electrodes prepared by simple and reliable electrodeposition methods. Glassy carbon and platinum electrodes were modified with composite films made from gold nanoparticles (AuNPs) and a carbosilane-dendrimer possessing peripheral electronically communicated ferrocenyl units (Dend), using potentiostatic and cycling techniques. AuNPs with diameters in the range 12–24nm were assembled to form fractal and flowerlike structures on the surface of electrodes. The modified electrodes exhibited remarkable electrocatalytic activity toward the oxidation of nitrite giving higher peak currents at lower oxidation overpotentials than those found for the bare electrode and the dendrimer-modified electrode. The voltammetric study showed that the electrochemical oxidation of nitrite involves one-electron in the rate-determining step reaction. It is proposed that the mechanism for the interaction of nitrite with ferrocene groups to be oxidized involves attachment to the ferrocene center. At the AuNPs it is possible to consider that the oxidation of NO2− to NO2 probably proceeds through an adsorption stage. The heterogeneous rate constant, k, for the oxidation of nitrite at the surface of the modified electrodes was determined by rotating disk electrode voltammetry using Koutecky–Levich plots. The transfer coefficients for electrocatalytic oxidation of nitrite under the experimental conditions were also investigated in this study. Under the optimum conditions the sensor has a linear response in the 10μM to 5mM concentration range, a high sensitivity of 44.8μAμM−1, and a low detection limit of 2.0×10−7M. Most common ions do not cause interferences. The sensor was successfully applied to the determination of nitrite in natural water samples.

Amperometric detection of nitrite in water samples by use of electrodes consisting of palladium-nanoparticle-functionalized multi-walled carbon nanotubes

An amperometric determination of nitrite in different water samples was evaluated using palladium nanoparticles (PdNPs) decorated functionalized multiwalled carbon nanotubes (f-MWCNT) modified glassy carbon electrode. The f-MWCNT/PdNPs composite modified electrode was prepared by electrodeposition of PdNPs on the surface of f-MWCNT modified electrode. The parameters such as effect of number of cycles of PdNPs deposition, drop coated amount of f-MWCNT and effect of pH were optimized and discussed in detail. As-prepared f-MWCNT/PdNPs composite modified electrode exhibits excellent electrocatalytic activity towards the oxidation of nitrite compared to MWCNT, f-MWCNT and PdNPs modified electrodes. Amperometric i-t method was used to determine nitrite and the response of the nitrite on modified electrode was linear over the concentration from 0.05 to 2887.6μM. The response time of the sensor was estimated as 3s with the detection limit of 22nM. The fabricated f-MWCNT/PdNPs composite modified electrode shows its satisfactory practical ability in nitrite containing different water samples, which authenticate its potential ability for determination of nitrite.

Amperometric detection of nitrite using a nanometer-sized gold colloid modified pretreated glassy carbon electrode

We have developed a novel nitrite sensor based on the immobilization of nanometer-sized gold colloid attached to an ethylenediamine monolayer-modified electrochemically pretreated glassy carbon electrode. The electrochemical behavior and mechanism of the modified electrode towards the reduction of nitrite was studied. The electrode exhibited sensitive response to nitrite with a detection limit of 4.5 × 10−5 M (S/N = 3) and a linear range from 1.3 × 10−4 M to 4.4 × 10−2 M. The method was successfully applied to the detection of nitrite in real samples.

Amperometric Detection of Nitrite on Glassy Carbon Electrode Modified with Cobalt Nitroprusside

The glassy carbon electrode (GCE) modified with cobalt nitroprusside (CoNP) was prepared by electrochemical method. The CoNP modified electrode (ME) prepared electrochemically on a GCE in two-step. The electrochemical behavior of the modified electrode was studied by cyclic voltammetric technique. The cyclic voltammogram of CoNP showed a redox couple with formal potential [E 0 =(Epa+Epc)/2] of 500 mV vs. SCE. The electrocatalytic oxidation of nitrite was studied on the CoNP modified glassy carbon electrode. The CoNP films on the glassy carbon electrode show an excellent electrocatalytic activity toward the oxidation of nitrite in 0.5 mol L -1 KNO3. Hydrodynamic amperometry was used to the detection of nitrite with CoNP. The linear detection limit of the CoNP elctrode for NO2 was from 20×10 -6 to 220×10 -4 mol L -1 and the detection limit was 10×10 -6 mol L -1 (S/N=3).

Amperometric detection of Nitrite, Iodate and Periodate on Glassy Carbon Electrode modified with Thionin and Multi-wall Carbon Nanotubes

Amperometric detection of Nitrite, Iodate and Periodate on Glassy Carbon Electrode modified with Thionin and Multi-wall Carbon Nanotubes

Amperometric detection of nitrite, iodate and periodate at glassy carbon electrode modified with catalase and multi-wall carbon nanotubes

The electrocatalytic reduction of nitrite, iodate and periodate has been studied at catalase-incorporated multi-wall carbon nanotubes (MWCNTs) supported on a glassy carbon electrode. Cyclic voltammograms of the catalase-incorporated MWCNTs indicate a pair of well defined and nearly reversible redox couple. The embedded catalase in the MWCNTs films show excellent electrocatalytic activity toward iodate, nitrite and periodate reduction in acidic solutions at unusually positive potentials. Furthermore, catalase-modified MWCNTs supported on a glassy carbon rotating disk electrode shows good analytical performance for amperometric determination of selected anions. Under optimized condition of the amperometry method the concentration calibration range, detection limit and sensitivity are 1 μM to 6 mM, 0.15 μM and 55.6 nA/μM for periodate, 1 μM to 5 mM, 0.2 μM and 44.4 nA/μM for iodate and 5 μM to 10 mM, 1.35 μM and 7 nA/μM for nitrite, respectively. Meanwhile, the catalase activity in the carbon nanotubes films is significantly enhanced with apparent Michaelis–Menten constants of 0.9, 1.41 and 1.14 mM for iodate, periodate and nitrite, respectively. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long term life, fast amerometric response (within 5 s), wide linear range, technical simplicity and possibility of preparation at a short period of time are great advantages of this sensor. The obtained results show potential and promising practical application for the catalase-MWCNTs-modified electrode in amperometric sensor for oxoanions determination. This sensor can be used as an amperometric detector for analysis of nitrite, iodate and periodate in chromatographic or flow systems.

Amperometric detection of nitrite and nitrate at tetraruthenated porphyrin-modified electrodes in a continuous-flow assembly

The modification of a glassy carbon surface by coating with an electrostatically assembled film of tetraruthenated cobalt porphyrin/(meso-tetra(4-sulphonatephenyl)porphyrinate zinc(II) yields an indicator electrode that allows the determination of nitrite to be performed with a limit of detection of 0.1 μM in a flow injection configuration. The dynamic range extends up to 1000 μM and the repeatability of the measurements was evaluated to be 1.5% with a throughput of 50 samples per hour. The efficiency of the bilayered film to mediate the electron transfer allows the determinations to be performed at a less positive potential (+0.75 V) with enhanced sensitivity. The coating also prevents the surface poisoning and its stability is maintained over several weeks. The same detector was used for determination of nitrate after reduction to nitrite in a reductor column containing copperised cadmium. This method was used for the determination of nitrate and nitrite in mineral water, saliva and cured meats, the results being in agreement with certified values and those obtained by using recommended procedures.

The application of strongly reducing agents in flow injection analysis Part 6. Molybdenum(III)

The application of molybdenum(III) as reducing agent in flow injection analysis is described. Molybdenum(III), which is unstable to oxidation by air, is generated in-line from the stable molybdenum(VI) by means of a Jones reductor column. With spectrophotometric detection, iodate, uranium(VI), and vanadium(V) and nitrite can be determined in the concentration range 5 x 10 −5 x 10 −3 M at an injection rate of 3 min −1. Amperometric detection of nitrite is also described.