Mercury Determination in Fish Samples by Chronopotentiometric Stripping Analysis Using Gold Electrodes Prepared from Recordable CDs

Upcycling Compact Discs for Flexible and Stretchable Bioelectronic Applications

Electronic waste is a global issue brought about by the short lifespan of electronics. Viable methods to relieve the inundated disposal system by repurposing the enormous amount of electronic waste remain elusive. Inspired by the need for sustainable solutions, this study resulted in a multifaceted approach to upcycling compact discs. The once-ubiquitous plates can be transformed into stretchable and flexible biosensors. Our experiments and advanced prototypes show that effective, innovative biosensors can be developed at a low-cost. An affordable craft-based mechanical cutter allows pre-determined patterns to be scored on the recycled metal, an essential first step for producing stretchable, wearable electronics. The active metal harvested from the compact discs was inert, cytocompatible, and capable of vital biopotential measurements. Additional studies examined the material’s resistive emittance, temperature sensing, real-time metabolite monitoring performance, and moisture-triggered transience. This sustainable approach for upcycling electronic waste provides an advantageous research-based waste stream that does not require cutting-edge microfabrication facilities, expensive materials, and high-caliber engineering skills.

Electronic waste is a global issue brought about by the short lifespan of electronics. Here, the authors report a process to upcycle compact discs into flexible and stretchable bio-electronics.

A carbon-based fluorescent probe (N-CDs) encapsulated in a zeolite matrix (NaFZ) for ultrasensitive detection of Hg (II) in fish

In this work, a novel strategy was addressed to fabricate new sensing probe (N-CDs@NaFZ) from nitrogen doped carbon dots (N-CDs) confined in Al-free ferrisilicates zeolite (NaFZ) by hydrothermal/solvothermal method. The probe was systematically characterized by HR-TEM, FTIR, energy dispersive X-ray (EDX), powder X-ray diffraction, and UV-Vis absorption and fluorescence spectrophotometers. Characterization of the designed nanocomposite template N-CDs@NaFZ by fluorescence spectrum demonstrates a variety of important conducts as stability improvements, reasonable dispersibility in water, highly emission intensity enhancement at 435 nm when excited at 340 nm, excitation independent fluorescence behaviors, great quantum yield percentage of 91.2%, and narrow size distribution 12 nm, as a nano-space confinement effect of zeolite effectively increase the rigidity of N-CDs. Based on the fluorescence quenching mechanism, the designed approach exhibits an excellent selectivity and good sensitive response to the presence of Hg(II) ions under ambient temperature, with a wide linear range of 0.1-1500 nM and lower detection limits of 5.5 pM. Influences of variables pH and incubation time were optimized. The N-CDs@NaFZ sensor was effectively applied for the detection of Hg(II) ions in the farmed and wild rainbow trout fishes, and the results are in reasonable agreement when compared with that obtained by the cold vapor atomic absorption method.

Disposable electrodes from waste materials and renewable sources for (bio)electroanalytical applications

The numerous advantages of disposable and screen-printed electrodes (SPEs) particularly in terms of portability, sensibility, sensitivity and low-cost led to the massive application of these electroanalytical devices. To limit the electronic waste and recover precious materials, new recycling processes were developed together with alternative SPEs fabrication procedures based on renewable, biocompatible sources or waste materials, such as paper, agricultural byproducts or spent batteries. The increased interest in the use of eco-friendly materials for electronics has given rise to a new generation of highly performing green modifiers. From paper based electrodes to disposable electrodes obtained from CD/DVD, in the last decades considerable efforts were devoted to reuse and recycle in the field of electrochemistry. Here an overview of recycled and recyclable disposable electrodes, sustainable electrode modifiers and alternative fabrication processes is proposed aiming to provide meaningful examples to redesign the world of disposable electrodes.

A Portable Setup for the Voltammetric Determination of Total Mercury in Fish with Solid and Nanostructured Gold Electrodes

A simple procedure for field fish sample pretreatment was developed. This treatment in combination with square wave anodic stripping voltammetry (SW-ASV) with solid gold electrodes (SGE) and gold nanoparticle-modified glassy carbon electrodes (AuNPs-GCE) was applied for the determination of total mercury content. A certified reference material (CRM, Tuna Fish BCR 463), ten freeze-dried samples of canned tuna and two fresh fish samples were analysed both with a bench-top voltammetric analyser after microwave digestion and with a portable potentiostat after mild eating using a small commercial food warmer. The results obtained by the two SW-ASV approaches and by a Direct Mercury Analyser (DMA), the official method for mercury determination, were in very good agreement. In particular, (i) the results obtained with in field procedure are consistent with those obtained with the conventional microwave digestion; (ii) the presence of gold nanoparticles on the active electrode surface permits an improvement of the analytical performance in comparison to the SGE: the Limit of Quantification (LOQ) for mercury in fish-matrix was 0.1 μg L-1 (Hg cell concentration), corresponding to 0.06 mg kg-1 wet fish, which is a performance comparable to that of DMA. The pretreatment proposed in this study is very easy and applicable to fresh fish; in combination with a portable potentiostat, it proved to be an interesting procedure for on-site mercury determination.

Electrode-modified with nanoparticles composed of 4,4′-bipyridine-silver coordination polymer for sensitive determination of Hg(ii), Cu(ii) and Pb(ii)

Nanoparticles of 4,4′-bipyridine-silver coordination polymer were used for the modification of glassy carbon electrode with applications in analytical chemistry.

Optimization of analytical procedures for the simultaneous voltammetric determination of total Hg(II) in presence of Cu(II) in environmental matrices

The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems.

The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively.

The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d.

Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).