A new nano-composite electrode as a copper (II) selective potentiometric sensor

Ligands as copper and nickel ionophores: Applications and implications on wastewater treatment

Modern society depends on many finite natural resources, from which metals are of great importance. Copper and nickel's relevance is due to their vast applications, resulting in high market value and demand. As such, their polluting emissions are also significant and their removal from wastewaters is imperative. Moreover, effluent treatment techniques can be used to recover the metallic cations, via selective processes. In this review, copper and nickel selective ligands in the literature are surveyed. These are most commonly Schiff bases, along with crown ethers and porphyrins. They are usually employed in ion sensing (colorimetric chemosensors or electrodes) with great success - the disruption in response of colorimetric sensors is up to 7% and binding constants are usually at least one order of magnitude greater with the desired cation than with interferents. However, modified adsorbents are also reported. The possibilities of using ionophores in wastewater cleaning, allowing the treatment of effluents and the selective recovery of valuable materials, and their implications on new green policies is discussed.

EGFET-Based Sensors for Bioanalytical Applications: A Review

Since the 1970s, a great deal of attention has been paid to the development of semiconductor-based biosensors because of the numerous advantages they offer, including high sensitivity, faster response time, miniaturization, and low-cost manufacturing for quick biospecific analysis with reusable features. Commercial biosensors have become highly desirable in the fields of medicine, food, and environmental monitoring as well as military applications, whereas increasing concerns about food safety and health issues have resulted in the introduction of novel legislative standards for these sensors. Numerous devices have been developed for monitoring biological processes such as nucleic acid hybridization, protein–protein interaction, antigen–antibody bonds, and substrate–enzyme reactions, just to name a few. Since the 1980s, scientific interest moved to the development of semiconductor-based devices, which also include integrated front-end electronics, such as the extended-gate field-effect transistor (EGFET) biosensor, one of the first miniaturized chemical sensors. This work is intended to be a review of the state of the art focused on the development of biosensors and chemosensors based on extended-gate field-effect transistor within the field of bioanalytical applications, which will highlight the most recent research reported in the literature. Moreover, a comparison among the diverse EGFET devices will be presented, giving particular attention to the materials and technologies.

Determination of total mercury in seafood by ion-selective electrodes based on a thiol functionalized ionic liquid

A mercury(II) ion-selective electrode with an ionic liquid (IL), 1-methyl-2-butylthioimidazolium bis(trifluoromethanesulphonyl)imide ([C₁C₄Sim]NTf₂) as active material was constructed. Parameters affecting the performance of the electrodes such as the dosages of the IL and carbon nanotubes and the aqueous pH values were investigated. Experimental results indicated that the optimal composition of the electrode filling material was 47.6% [C₁C₄Sim]NTf₂, 47.6% tetrabutylphosphonium bis(trifluoromethanesulphonyl) imide (TBPNTf₂) and 4.8% carboxylic multi-walled carbon nanotubes (MWCNTs-COOH). Under the selected conditions, the proposed electrodes showed a good linear response in the concentration range of 10⁻¹⁰–10⁻⁵ mol L⁻¹ and had a detection limit of 4.1 × 10⁻¹¹ mol L⁻¹. No great interference from common metal ions was found. The proposed electrodes were applied to determine Hg²⁺ in seafood samples; the results were comparable to those of the direct mercury analyzer.

Preparation of Highly Dispersed Reduced Graphene Oxide Modified with Carboxymethyl Chitosan for Highly Sensitive Detection of Trace Cu(II) in Water

In this article, reduced graphene oxide (RGO)/carboxymethyl chitosan (CMC) composites (RGO/CMC) were synthesized by a hydrothermal method through in-situ reduction and modification of graphene oxide (GO) in the presence of CMC. An electrochemical sensor for the determination of Cu(II) by differential pulse anodic stripping voltammetry (DPASV) was constructed by an electrode modified with RGO/CMC. The fabricated electrochemical sensor shows a linear range of 0.02⁻1.2 μmol·L^-1, a detection limit of 3.25 nmol·L^-1 (S/N = 3) and a sensitivity of 130.75 μA·μmol·L^-1·cm^-2, indicating the sensor has an excellent detection performance for Cu(II).

Simultaneous determination of hydroxylamine and phenol using a nanostructure-based electrochemical sensor

The electrochemical oxidation of hydroxylamine on the surface of a carbon paste electrode modified with carbon nanotubes and 2,7-bis(ferrocenyl ethyl)fluoren-9-one is studied. The electrochemical response characteristics of the modified electrode toward hydroxylamine and phenol were investigated. The results showed an efficient catalytic activity of the electrode for the electro-oxidation of hydroxylamine, which leads to lowering its overpotential. The modified electrode exhibits an efficient electron-mediating behavior together with well-separated oxidation peaks for hydroxylamine and phenol. Also, the modified electrode was used for determination of hydroxylamine and phenol in some real samples.