In situ bismuth-film electrode for square-wave anodic stripping voltammetric determination of tin in biodiesel

Stripping Voltammetry with Nanomaterials-based Electrode in the Environmental Analysis of Trace Concentrations of Tin

A method for the voltammetric determination of tin using a multiwall carbon nanotubes/spherical glassy carbon (CNTs/SGC) electrode is described. The new procedure is based on the adsorptive accumulation of the Sn(II)-cupferron complex on a CNTs/SGC electrode modified with a lead film, followed by electrochemical reduction of the adsorbed species. The optimal experimental conditions include the use of 0.10 mol L-1 acetate buffer (pH 5.7), 4.0×10-4 M cupferron and 1.0×10-4 M Pb(II). The peak current is proportional to the concentration of Sn(II) over the range of 1.0×10-9 -1.0×10-7 M and the detection limit is 3.1×10-10 M for a 95 s accumulation time. The proposed method was used to determine tin in real samples and certified reference materials.

Electrochemical Methods for the Analysis of Trace Tin Concentrations-Review

Tin determination allows for the monitoring of pollution and assessment of the impact of human activities on the environment. The determination of tin in the environment is crucial for the protection of human health and ecosystems, and for maintaining sustainability. Tin can be released into the environment from various sources, such as industry, transportation, and electronic waste. The concentration of tin in the environment can be determined by different analytical methods, depending on the form of tin present and the purpose of the analysis. The choice of an appropriate method depends on the type of sample, concentration levels, and the available instrumentation. In this paper, we have carried out a literature review of electrochemical methods for the determination of tin. Electrochemical methods of analysis such as polarography, voltammetry, and potentiometry can be used for the determination of tin in various environmental samples, as well as in metal alloys. The detection limits and linearity ranges obtained for the determination of tin by different electrochemical techniques are collected and presented. The influence of the choice of base electrolyte and working electrode on signals is also presented. Practical applications of the developed tin determination methods in analyzing real samples are also summarized.

Robust solvatochromic carbon quantum dots for selective detection of water and Sn4+ and specific lipid imaging

Developing carbon quantum dots (CQDs) with the solvatochromic effect and exploring multifunctional applications remains challenging. Herein, robust solvatochromic carbon quantum dots (RS-CQDs) with emission shift up to ∼62 nm from yellow to red was fabricated by the hydrothermal method. The RS-CQDs was used to detect water and Sn⁴⁺ in the linear ranges and limits of detection of 2.0-97.6% and 0.14% and 6.24-53.18 μM and 66.3 nM, respectively, and was further applied to determine Sn⁴⁺ in practical water samples with satisfactory results. In addition, RS-CQDs exhibited bright red emission in oil media with a 9.7-fold increase in fluorescence relative to aqueous media, making them a wash-free probe for specifically staining lipids. Compared to the commercial lipid marker BODIPY 493/503, the RS-CQDs-based probe has significant advantages, such as longer emission, larger Stokes shift, and better photostability, ensuring that RS-CQDs-based marker can implement real-time and wash-free monitoring and imaging of lipids in living cells, liver tissues, zebrafish embryos, and zebrafish larvae. This study provides a novel research direction for the development of metal-doped CQDs by demonstrating RS-CQDs as the viability of fluorescence probes for water and Sn⁴⁺ detection and the efficiency of RS-CQDs as a fluorescent marker for lipid imaging.

Inexpensive Bismuth-Film Electrode Supported on Pencil-Lead Graphite for Determination of Pb(II) and Cd(II) Ions by Anodic Stripping Voltammetry

The present work reports the development and application of bismuth-film electrode (BiFE), obtained by in situ method on the pencil-lead graphite surface, for simultaneous Cd(II) and Pb(II) determination at trace levels, as alternative to replace the mercury-film electrodes. Experimental factors, deposition time (t_d), deposition potential (E_d), and Bi(III) concentration (C_Bi), were investigated by applying a 2³ factorial design using 0.10 mol/L acetate buffer solution (pH 4.5) as supporting electrolyte. The analysis conditions of the differential pulse technique were t_d = 250 s, E_d = -1.40 V, and C_Bi = 250 mg L⁻¹. The validation of the method employing BiFE was accomplished by determination of merit figures. The detection limits were of 11.0 μg L⁻¹ for Cd(II) and 11.5 μg L⁻¹ for Pb(II), confirming that proposed method is attractive and suitable for heavy metals determination. Additionally, the BiFE developed was successfully applied for the Cd(II) and Pb(II) determination in wastewater sample of battery industry.

Carbon nanostructured films modified by metal nanoparticles supported on filtering membranes for electroanalysis

A novel methodology to prepare sensors based on carbon nanostructures electrodes modified by metal nanoparticles is proposed. As a proof of concept, a novel bismuth nanoparticle/carbon nanofiber (Bi-NPs/CNF) electrode and a carbon nanotube (CNT)/gold nanoparticle (Au-NPs) have been developed. Bi-NPs/CNF films were prepared by 1) filtering a dispersion of CNFs on a polytetrafluorethylene (PTFE) filter, and 2) filtering a dispersion of Bi-NPs chemically synthesized through this CNF/PTFE film. Next the electrode is prepared by sticking the Bi-NPs/CNF/PTFE film on a PET substrate. In this work, Bi-NPs/CNF ratio was optimized using a Cd²⁺ solution as a probe sample. The Cd anodic stripping peak intensity, registered by differential pulse anodic stripping voltammetry (DPASV), is selected as target signal. The voltammograms registered for Cd stripping with this Bi-NPs/CNF/PTFE electrode showed well-defined and highly reproducible electrochemical. The optimized Bi-NPs/CNF electrode exhibits a Cd²⁺ detection limit of 53.57 ppb. To demonstrate the utility and versatility of this methodology, single walled carbon nanotubes (SWCNTs) and gold nanoparticles (Au-NPs) were selected to prepare a completely different electrode. Thus, the new Au-NPs/SWCNT/PTFE electrode was tested with a multiresponse technique. In this case, UV/Vis absorption spectroelectrochemistry experiments were carried out for studying dopamine, demonstrating the good performance of the Au-NPs/SWCNT electrode developed.