Electrochemical simultaneous determination of nitrophenol isomers at nano-gold modified glassy carbon electrode

Hydrothermal Synthesis of Cr2Se3 Hexagons for Sensitive and Low-level Detection of 4-Nitrophenol in Water

We report a simple hydrothermal method used for the synthesis of Cr₂Se₃ hexagons (h-Cr₂Se₃) and its application towards electrochemical sensing of 4-nitrophenol (4-NP). The formation of h-Cr₂Se₃ was confirmed by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical activity of the h-Cr₂Se₃ modified screen-printed carbon electrode (SPCE) towards 4-NP was studied using cyclic voltammetry (CV) and amperometric i-t techniques. Typically, the obtained results were compared with those for a bare SPCE. The CV result clearly reveals that h-Cr₂Se₃ modified SPCE has higher catalytic activity towards reduction of 4-NP than bare SPCE. Hence, h-Cr₂Se₃ modified SPCE was concluded as a viable sensor for sensitive determination of 4-NP. Under optimized conditions, h-Cr₂Se₃ modified SPCE demonstrates the excellent capacity to detect the 4-NP in a linear range from 0.05 µM to 908.0 µM. The LOD and sensitivity in detection of 4-NP were determined at 0.01 µM and 1.24 µAµM⁻¹ cm⁻² respectively. The sensor is highly selective and stable and shows reproducible recovery of 4-NP in domestic supply and river water samples.

A new strategy for the sensitive electrochemical determination of nitrophenol isomers using β-cyclodextrin derivative-functionalized silicon carbide

An illustration of simultaneous electrochemical determination of nitrophenol isomers using β-cyclodextrin derivative-functionalized silicon carbide.

Magnetite-platinum nanoparticles-modified glassy carbon electrode as electrochemical detector for nitrophenol isomers

A glassy carbon electrode was modified with magnetite and platinum nanoparticles stabilized with 3-n-propyl-4-picoline silsesquioxane chloride. This chemically-modified electrode is proposed for the first time for the individual or simultaneous electrochemical detection of nitrophenol isomers. Nanoparticles act as catalysts and also increase the surface area. The polymer stabilizes the particles and provides the electrochemical separation of isomers. Under optimized conditions, the reduction peak currents, obtained by differential-pulse voltammetry, of 2-, 3-, and 4-nitrophenol increased linearly with increases in their concentration in the range of 0.1-1.5μmolL^-1. In individual analysis, the detection limits were 33.7nmolL^-1, 45.3nmolL^-1 and 48.2nmolL^-1, respectively. Also, simultaneous analysis was possible for 2-, and 4-nitrophenol. In this case, the separation of the peak potentials was 0.138V and the detection limits were 69.6nmolL^-1 and 58.0nmolL^-1, respectively. These analytical figures of merit evidence the outstanding performance of the modified electrode, which was also successfully applied to the individual determination of isomers in environmental and biological samples. The magnetite and platinum nanoparticles modified glassy carbon electrode was able to detect nitrophenol isomers at the ppm level in rain water and human urine samples.

Determination of 4-nitrophenol in water by use of a screen-printed carbon electrode modified with chitosan-crafted ZnO nanoneedles

The toxicity and environmental pollution by nitro aromatic compounds in water samples is the most recognized problem in worldwide. Hence, we have developed a simple and highly sensitive electrochemical method for the determination of 4-nitrophenol (4-NP) in water samples based on a chitosan (CHT) crafted zinc oxide nanoneedles (ZnO NDs) modified screen printed carbon electrode. The CHT/ZnO NDs were characterized by Field emission scanning electron microscope, Fourier transform infrared spectroscopy and X-ray diffraction technique. The CHT/ZnO NDs modified electrode showed an enhanced electrocatalytic activity and lower potential detection towards 4-NP, compared with other modified electrodes. Under optimum conditions, the differential pulse voltammetry (DPV) response of CHT/ZnO NDs modified electrode displayed a wide linear response range from 0.5 to 400.6μM towards the detection of 4-NP with a detection limit (LOD) of 0.23μM. The CHT/ZnO NDs modified electrode was used for specific and sensitive detection of 4-NP in presence of possible interfering species and common metal ions with long-term stability. In addition, the excellent analytical performance of the proposed sensor was successfully applied for determination of 4-NP in water samples.

Facile solvothermal decomposition synthesis of single phase ZnBi38O60 nanobundles for sensitive detection of 4-nitrophenol

We have developed the facile solvothermal decomposition route to fabricate a single phase zinc bismuthate (ZnBi₃₈O₆₀) binary composite nanostructure.

Nanostructured materials in electroanalysis of pharmaceuticals

Basic strategies and recent developments for the enhancement of the sensory performance of nanostructures in the electroanalysis of pharmaceuticals are reviewed. A discussion of the properties of nanostructures and their application as modified electrodes for drug assays is presented. The electrocatalytic effect of nanostructured materials and their application in determining low levels of drugs in pharmaceutical forms and biofluids are discussed.

Edge-carboxylated graphene anchoring magnetite-hydroxyapatite nanocomposite for an efficient 4-nitrophenol sensor

Surface chemistry and electrochemical properties of ball milled edge-carboxylated graphene anchored with magnetite-hydroxyapatite nanocomposites were studied through the sensitive and selective detection of 4-NP by cyclic voltammetry and differential pulsed voltammetry.

Gold nanoparticles hosted in a water-soluble silsesquioxane polymer applied as a catalytic material onto an electrochemical sensor for detection of nitrophenol isomers

The water-soluble 3-n-propyl-4-picolinium silsesquioxane chloride (Si4Pic(+)Cl(-)) polymer was prepared, characterized and used as a stabilizing agent for the synthesis of gold nanoparticles (nAu). The ability of Si4Pic(+)Cl(-) to adsorb anionic metal complexes such as AuCl4(-) ions allowed well-dispersed nAu to be obtained with an average particle size of 4.5nm. The liquid suspension of nAu-Si4Pic(+)Cl(-) was deposited by the drop coating method onto a glassy carbon electrode (GCE) surface to build a sensor (nAu-Si4Pic(+)Cl(-)/GCE) which was used for the detection of o-nitrophenol (o-NP) and p-nitrophenol (p-NP). Under optimized experimental conditions the reduction peak current increased with increasing concentrations of both nitrophenol isomers in the range of 0.1-1.5μmolL(-1). The detection limits were 46nmolL(-1) and 55nmolL(-1) for o-NP and p-NP, respectively. These findings indicate that the nAu-Si4Pic(+)Cl(-) material is a very promising candidate to assemble electrochemical sensors for practical applications in the field of analytical chemistry.