Anodic Stripping Research Articles

Spectroscopic investigations of a commercial graphite screen printed electrode modified by bismuth oxide drop deposition and electrochemical reduction, for cadmium and lead ions simultaneous determination

A single use graphite screen-printed electrode (GSPE) was easily modified, to take advantage of the proven affinity of the nontoxic post-transition metal bismuth (Bi), for metal ions to be detected by Square Wave Anodic Stripping Voltammetry (SWASV). A bismuth oxide (Bi2O3) or a chitosan coated (CS@Bi2O3) nanopowder suspension was drop-casted on the graphite working electrode (WE) surface, giving rise to the precursor of a Bi-modified GSPE. After that, an electrochemical reduction was performed to obtain the Bi– or the CS@Bi–GSPE.X-ray photoelectron spectroscopy and micro-X-ray fluorescence investigations were performed on the graphitic structure pre and post modification. The bismuth oxide deposition amount was considered as critical parameter to sensor performance, indicating a minimum and maximum threshold. Under improved measurement conditions, with a 300 s pre-concentration time, the attained sensors exhibited a linearity in the range (2.0–20.0) μg L−1 in the simultaneous analysis of Pb(II) and Cd(II). The Bi–GSPE showed LODs of 1.7 and 0.5 μg L−1 for Cd(II) and Pb(II) respectively, while 1.5 μg L−1 for Cd(II) and 0.2 μg L−1 for Pb(II) were recorded by the CS@Bi–GSPE. As an applicative proof in real sample, a spike test was carried out in a ground water sample, without any preliminary sample treatment.

Electrochemical sensing of Pb2+, Cu2+, and Hg2+ by an aminoclay-based porous covalent organic polymer/ multi-walled carbon nanotubes modified glassy carbon electrode

We present a novel electrochemical sensor for the simultaneous detection of Lead (Pb2+), Copper (Cu2+), and Mercury (Hg2+) ions in seafood samples using differential pulse anodic stripping voltammetry (DPASV) technique. The sensor incorporates an aminoclay-based porous covalent organic polymer (AC-PCOP) derived from the polymerization of aminoclay and 1,3,5-benzenetricarboxylic acid (trimesic acid). To enhance conductivity, the AC-PCOP is combined with multi-walled carbon nanotubes (MWCNTs) and utilized for modifying the surface of the glassy carbon electrode (GCE). The AC-PCOP was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and infrared spectroscopy (IR). These analyses confirmed the presence of a hierarchical architecture in the AC-PCOP, which exhibited a spherical shape. The proposed modifier facilitates the deposition-stripping process and electron diffusion between electrolyte and heavy metal ions. Optimized conditions yielded limit of detections (LODs) of 0.0006, 0.0016, and 0.0003 nM, with linear ranges from 0.002 to 1000 nM, 0.005 to 1000 nM, and 0.001 to 1000 nM for Pb2+, Cu2+, and Hg2+, respectively. The sensor successfully measured these ions in seafood samples. Control experiments and validation were performed using cold vapor atomic absorption spectrometry (CVAAS) to determine the ions in the chosen food samples.

Development of pectin-based gel electrolyte for wireless electrochemical determination of cadmium and lead using smartphone

A portable device offering effortlessness, mobility, and affordability for real-time and on-site monitoring of heavy metals is currently in great demand to maintain environmental sustainability. Herein, a platform utilizing a biopolymeric gel-based electrolyte for the on-field simultaneous determination of Cd(II) and Pb(II) is described. Pectin, a natural polymer, was exploited as a chemical delivery medium on account of its biodegradability, environmental friendliness, and rapid dissolving characteristics. The gel electrolyte was prepared by having pectin dissolved in KCl mixed with Sb(III)–Bi(III) bimetallic alloy solution, and casted onto a paper substrate. An in situ bimetallic alloy and pre-mixed bismuth nanoparticles modified screen-printed graphene electrode (Sb–Bi/BiNP/SPGE) were employed to enhance the electrochemical signals of Cd(II) and Pb(II) for the differential pulse anodic stripping voltammetry (DPASV). It was demonstrated that the platform was capable of generating sharp and well-defined current signals, achieving the low detection limits of 50.98 ng mL−1 for Cd(II) and 40.80 ng mL−1 for Pb(II). The reproducibility, as indicated by the relative standard deviation, was found to be less than 10.4 % (n = 10) for the developed gel-based device when coupled with a wireless near field communication (NFC) potentiostat. Lastly, the obtained sensor was applied for quantification of Cd and Pb in potentially contaminated groundwater samples. The recoveries obtained were satisfactorily within the acceptable range. The newly designed platform exhibited several advantages, including small sample volume (μL), low-cost, no sample preparation requirements, and being environmentally friendly. The convenience of a portable device utilizing the proposed biopolymeric gel-based electrolyte for on-field analysis makes it highly appealing for various applications.

Synthesis and application of bismuth nanoparticle-loaded longan porous carbon for simultaneous electrochemical determination of Pb(II) and cd(II) in seafoods

The discarded longan shell-derived porous carbon material (LPC) served as a scaffold for synthesizing bismuth nanoparticle-loaded longan porous carbon nanocomposite (BiNPs@LPC) via a hydrothermal method. Then BiNPs@LPC was utilized to modify screen-printed carbon electrodes (SPCE) for simultaneous detection of Pb(II) and Cd(II) by square wave anodic stripping voltammetry (SWASV). The material was thoroughly characterized by scanning electron microscopy, X-ray diffraction, Raman spectra, Brunauer-Emmett-Teller analysis, electrochemical impedance spectroscopy and cyclic voltammetry. BiNPs@LPC exhibited abundant porous structures, high surface area, and numerous active sites, which could improve significantly response sensitivity. Under optimal conditions, the peak currents of Pb(II) and Cd(II) exhibited favorable linear relationships with the concentration within a range of 0.1–150 μg L−1, with detection limits (S/N = 3) of 0.02 μg L−1 and 0.03 μg L−1, respectively. BiNPs@LPC/SPCE demonstrated remarkable selectivity, stability and repeatability. The proposed method was successfully applied for the detection of Pb(II) and Cd(II) in seafoods achieving satisfying recovery of 97.8%–108.3% and 96.7%–106.4%. These excellent test properties were coupled with convenience for batch preparation of the modified electrodes, highlighting its potential for practical applications in heavy metal detection of real samples.

Adaptive Fabrication of Electrochemical Chips with a Paste-Dispensing 3D Printer.

Electrochemical (EC) detection is a powerful tool supporting simple, low-cost, and rapid analysis. Although screen printing is commonly used to mass fabricate disposable EC chips, its mask is relatively expensive. In this research, we demonstrated a method for fabricating three-electrode EC chips using 3D printing of relatively high-viscosity paste. The electrodes consisted of two layers, with carbon paste printed over silver/silver chloride paste, and the printed EC chips were baked at 70 °C for 1 h. Engineering challenges such as bulging of the tubing, clogging of the nozzle, dripping, and local accumulation of paste were solved by material selection for the tube and nozzle, and process optimization in 3D printing. The EC chips demonstrated good reversibility in redox reactions through cyclic voltammetry tests, and reliably detected heavy metal ions Pb(II) and Cd(II) in solutions using differential pulse anodic stripping voltammetry measurements. The results indicate that by optimizing the 3D printing of paste, EC chips can be obtained by maskless and flexible 3D printing techniques in lieu of screen printing.

Voltammetry determination of Cd(II) and Pb(II) at TiO2/reduced graphene oxide modified electrodes

AbstractIn this article, a TiO2/reduced graphene oxide (rGO) composite was synthesized from rGO and soluble titanium hydroxide‐peroxide complexes. The obtained materials were characterized by X‐ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption, Raman spectroscopy and energy dispersive X‐ray spectroscopy‐elementary mapping. The TiO2/rGO composite was used as an electrode modifier for developing an electrochemical sensor to simultaneous analysis of Cd(II) and Pb(II) by using differential pulse anodic stripping voltammetry (DP‐ASV). Under optimal conditions, the linear correlation between the stripping peak current and the metal ion concentration is good in the range of 5–100 ppb for both metals (R2 ≥ 0.998), and a low detection limit (3.17 ppb for Cd(II) and 2.42 ppb for Pb(II)) was obtained. The interference study revealed that some metal cations had little influence on the DP‐ASV signals of Cd(II) and Pb(II). In addition, the developed electrode exhibited satisfied reproducibility and repeatability. The TiO2/rGO‐modified electrode was tested toward the detection of Cd(II) and Pb(II) in river waters and the obtained exceptional recoveries and results were further associated with AAS results. This study indicates that the TiO2/rGO composite might be an alternative for practical applications in the electrochemical determination of heavy metal ions in aquatic solutions.

Simultaneous Electrochemical Detection of Cu2+ and Zn2+ in Pig Farm Wastewater.

In recent years, the rapid development of pig farming has led to a large quantity of heavy metal-polluted wastewater. Thus, it was desirable to develop a simple heavy metal detection method for fast monitoring of the wastewater from the pig farms. Therefore, there was an urgent need to develop a simple method for rapidly detecting heavy metal ions in pig farm wastewater. Herein, a simple electrochemical method for simultaneous detection of Cu2+ and Zn2+ was developed and applied to pig farm wastewater. With a glassy carbon electrode and anodic stripping voltammetry, simultaneous detection of Cu2+ and Zn2+ in water was achieved without the need for complicated electrode modification. Furthermore, it was found that the addition of Cd2+ can enhance the response current of the electrode to Zn2+, which increased the signal by eight times. After systematic optimization, the limit of detection (LOD) of 9.3 μg/L for Cu2+ and 45.3 μg/L for Zn2+ was obtained. Finally, it was successfully applied for the quantification of Cu2+ and Zn2+ with high accuracy in pig farm wastewater. This work provided a new and simple solution for fast monitoring of the wastewater from pig farms and demonstrated the potential of electrochemical measurement for application in modern animal husbandry.

Superior performance of N-doped carbon Nanoonions/Nafion based microfluidic electrochemical Cd2+ sensor when compared to Screen-Printed Carbon-Based electrode devices

The sensing of cadmium is important due to its highly toxic effects on various organs of humans and animals. Commonly employed are screen-printed carbon-based electrodes (SPCE) as suitable low-cost sensing platform. Microfluidic electrochemical sensor (μCS) can also be portable, highly sensitive, and low-cost but are up to now only seldom studied and applied. Here we demonstrate the superior performance of μCS over SPCE arrangements for sensing ultra-trace of Cd2+. Additionally, N-doped carbon nanoonions (N-CNOs) are introduced as sustainable non-metallic modifier and employed for both sensing arrangements. The study depicted that employing the modifier the electrochemically active surface area and the electron transfer rate in both arrangements is improved together with improve sensitivity. Both arrangements were compared using cyclic voltammetry and electrochemical impedance spectroscopy in [Fe(CN)6]3−/4−, and also square-wave anodic stripping voltammetry (SWASV) for Cd2+ sensing. The µCS arrangement clearly outperforms the SPCE arrangement in signal strength. For the final device (μCS modified with N-CNOs) a linear concentration range from 1.0 to 100 μg L−1 was achieved. The limit of detection and sensitivity resulted to 0.25 μg L−1 and 1.02 μA µg−1 L cm−2, respectively. Besides this excellent sensitivity combines with high stability, which was tested for 8 repetitive measurements with a single device resulting in high reproducibility. Additionally, this procedure was favorably employed for measurements of Cd2+ in different real samples, which demonstrated the excellent applicability of the device for the adsorption and detection of heavy metal ions.

Highly sensitive and selective electrochemical monitoring of nickel in crude oil samples using cathodically pretreated-boron doped diamond electrode

Crude oil is a mixture of hydrocarbons found underground in liquid form and is a valuable fuel with a complex chemical structure. Crude oil is known to come from decaying plants and animals as a fossil product that emerged from the anaerobic process millions of years ago. In the formation of oil, it is accepted that crude oil has an organic origin, and most of the crude oil is found in sedimentary rocks, and the sediments have an organic and inorganic content.In this study, a voltammetric method was developed for the analysis of nickel, one of the metals with the highest density as a heavy metal in crude oil. In the developed voltammetric method, the boron-doped diamond electrode was activated in the cathodic direction at −3.0 V in 0.5 M H2SO4 media.As a result of this cathodic activation, nickel gave a very sensitive anodic signal around −0.15 V on the electrode surface. This anodic signal was determined to be linear in the range of 0.05–0.6 μM around −0.15 V in BR (pH 3.0) media by the anodic stripping voltammetry method. The limit of detection and the limit of quantification were determined to be 0.003 μM and 0.01 μM, respectively. The proposed method allowed the selective analysis of nickel in the crude oil sample without any separation and enrichment process.

Synthesis, properties, and applications of all-solid-state reference electrode based on AgTi2(PO4)3

High-density AgTi2(PO4)3 as a solid electrolyte was synthesised by a high-temperature solid-state process. The optimal sintering temperature was determined to obtain the best structural and electrical performance. Based on the as-prepared AgTi2(PO4)3 fast-ion conductor, a new type of all-solid-state reference electrode was prepared, and its electrochemical properties, such as cyclic voltammetry curves and potentials at varying pH, were investigated. A pH sensor was designed by combining an AgTi2(PO4)3 reference electrode with an Ir/IrO2 pH electrode. This pH sensor exhibited a good linear response to pH values in aqueous solutions and simulated seawater samples. In addition, a metal ion sensor, comprising the as-fabricated solid-state reference electrode, a Pt counter electrode, and a glassy carbon working electrode, was employed to quantify Cu2+, Hg2+, and Pb2+ concentrations using differential-pulse anodic stripping voltammetry. The resulting peak currents correlated with the metal ion concentrations and exhibited a low detection limit, good linearity, and wide detection range, which is suitable for performing chemical analysis in harsh marine environments.

Electrocatalytic detection of Hg(II) using a platinum electrode modified with composite film of cobalt(II) phthalocyanine tetra-substituted with 1-(methoxymethyl)-benzotriazole groups and co-electropolymerized polypyrrole

The presence of mercury adversely affects the daily lives of humankind due to its acute toxicity and environmental persistence. Therefore, the development of cost-effective smart materials which can allow the real time, ultrasensitive and discriminatory monitoring of mercury concentrations in industrial and municipal water treatment plants is an imperative. It is foreseen that this proposed water quality assurance measure will be of utmost importance to identify the culprits for the wide prevalence of this heavy metal ion in the environment. Herein, a platinum electrode (Pt) was modified via the simultaneous electropolymerization of polypyrrole (PPy) and the co-electrodeposition of tetra-[4-((1H-benzotriazole)methoxy)phthalocyaninato]cobalt(II) (CoPc-Bzt, 2, (Btz = benzotriazole)). The complementary electrode modification processes were performed in a 1:1 (v: v) DMF: acetonitrile containing 1 M tetrabutylammonium hexafluorophosphate electrolyte solution over 20 cycles using cyclic voltammetry to afford the chemically modified electrode (CME), Pt|PPy/2. Differential pulse anodic stripping voltammetry (DPASV) was used to detect Hg(II) ions using the CME within a 10 µM to 100 µM linear range while calculated limits of detection and quantification (LOD and LOQ) were determined as 3.11 and 10.00 µM, respectively. The analytical performance of the CME rendered a statistically accepted percentage recovery (97.4%) whereas that of Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) is 112.3%.

Pyridine-assisted electrodeposition of Au(1 1 1)-dominant gold nanonetworks on glassy carbon electrode for anodic stripping voltammetry analysis of As(III), Se(IV) and Cu(II)

Gold nanonetworks with Au(111)-dominant facets (AuNNs(1 1 1)-D) modified glassy carbon electrode (GCE) was simply fabricated by electroreduction of Au(III) with the assistance of pyridine (Py). Cyclic voltammetry of Au(III)-Py complex exhibits two sequential cathodic peaks, reflecting the reduction of Au(III) to Au(I) intermediate and then to Au(0). The as-prepared AuNNs(111)-D/GCE was characterized by scanning electron microcopy, X-ray diffraction and electrochemistry methods, and the results showed that the gold crystalline spread out in a nanonetworks architecture with good distribution, high aspect-ratios, large roughness and 90 % Au(111) facets. The coordination effects of Py, the inferior affinity of Py on Au(111) facets and the sustained generation of Au(I) intermediate contributed to such gold nanoarchitecture. Differential pluse anodic stripping voltammetry analysis of As(III), Se(IV) and Cu(II) was performed on the AuNNs(1 1 1)-D/GCE with high performance. Sensitivity values of 16.9 µA μM−1 (As(III)), 9.51 µA μM−1 (Se(IV)), 6.09 µA μM−1 (Cu(II)), as well as limit of detection values of 0.67 nM (As(III)), 1.1 nM (Se(IV)), 0.53 nM (Cu(II)) were obtained (S/N = 3), respectively. The AuNNs(111)-D/GCE was used for As(III), Se(IV) and Cu(II) determination in real drinkable water samples with satisfied results.

Synthesis of AgNPs/MnO2/rGO composite materials with adsorption properties and their application in analysis of anti-inflammatory and antibiotic agents

In this article, AgNPs and MnO2 were successively synthesized on the Graphene oxide (GO) substrate using an in situ method. The AgNPs/MnO2/GO nanocomposite material was modified onto the surface of a glassy carbon electrode (GCE) and the material was electrochemically reduced on the electrode surface. The material obtained after reduction was called AgNPs/MnO2/rGO, which was confirmed by X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) to examine the chemical bonding and by scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS) to demonstrate the elemental characteristics of the material. In addition, X-ray photoelectron spectroscopy (XPS) analysis was performed to determine the elemental composition, chemical state, and electronic state of the elements on the surface of the material. The application of the reduced material was for the analysis of Piroxicam and Ofloxacin using the differential pulse anodic stripping voltammetry (DP-ASV) method. The investigation of pH and scan rate (v) indicated that the synthesized material had adsorption properties and was applied for the analysis of the anti-inflammatory drug Piroxicam and the antibiotic Ofloxacin.

Simultaneous effect of pH, deposition time, deposition potential, and step potential on the stripping peak current of lead and cadmium by response surface methodology

In this paper, a simple voltammetric method has been reported for the lead, and cadmium determination using platinum nanoflowers modified glassy carbon electrode (PtNFs/GCE). The effects of pH, deposition time, deposition potential, step potential were investigated on the stripping peak current of lead, and cadmium based on response surface methodology (RSM). The results of RSM analysis and analysis of variance (ANOVA) have shown that the experimental data could be well described by quadratic regression equations with determination coefficients (R2) of 0.935, and 0.972 for the stripping peak current of lead, and cadmium, respectively. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum stripping peak current of the lead, and cadmium of 5.54µA, and 2.81µA, respectively were obtained at the optimum levels of process variables (pH (4.72), deposition potential (-1.14V), deposition time (120s), step potential (7mV)). Testing the model to analyze lead, and cadmium on the PtNFs/GC electrode using differential pulse anodic stripping voltammetry (DPASV) and obtained with the stripping peak current of the lead, and cadmium of 5.43µA, and 2.75 µA, respectively.

A Novel Thin-Layer Flow Cell Sensor System Based on BDD Electrode for Heavy Metal Ion Detection.

An electrochemical sensor based on a thin-layer flow cell and a boron-doped diamond (BDD) working electrode was fabricated for heavy metal ions determination using anodic stripping voltammetry. Furthermore, a fluidic automatic detection system was developed. With the wide potential window of the BDD electrode, Zn2+ with high negative stripping potential was detected by this system. Due to the thin-layer and fluidic structure of the sensor system, the electrodepositon efficiency for heavy metal ions were improved without using conventional stirring devices. With a short deposition time of 60 s, the system consumed only 0.75 mL reagent per test. A linear relationship for Zn2+ determination was displayed ranging from 10 μg/L to 150 μg/L with a sensitivity of 0.1218 μA·L·μg-1 and a detection limit of 2.1 μg/L. A high repeatability was indicated from the relative standard deviation of 1.60% for 30 repeated current responses of zinc solution. The system was applied to determine Zn2+ in real water samples by using the standard addition method with the recoveries ranging from 92% to 118%. The system was also used for the simultaneous detection of Zn2+, Cd2+, and Pb2+. The detection results indicate its potential application in on-site monitoring for mutiple heavy metal ions.

An innovative aluminium foil electrode modified with Al nanoparticles and EDTA for lead detection in biological samples

This study presents a novel Aluminium foil-based electrode characterized by its affordability, flexibility, and ease of modification with carboxylic moiety-containing organic molecules. Upon foil modification with Aluminium nanoparticles and EDTA (AlNP-EDTA/AlE), the modified electrode exhibits remarkable activity in the oxidation of lead at potentials around −0.4 V. The lead signal is derived from the oxidation of lead deposited on the electrode surface using anodic stripping voltammetry (ASV). The addition of EDTA to AlNP/AlE increased the anodic peak current of lead by more than 500 %. The surface characterization of the electrode was performed by scanning electron microscopy (SEM) and infrared spectroscopy (IR), while its electroactive properties were evaluated by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Optimal operating parameters include pH 2.1, square-wave voltammetry (SWV) with an accumulation time of 60 s and an accumulation potential of −0.8 V. A low detection limit of 0.20 µmol/L and a relative standard deviation (RSD) of 3.0 % were achieved using five different electrodes. The effectiveness of AlNP-EDTA/AlE was further demonstrated with consistent results in biological samples spiked with Pb.

Heavy metal sensing in plant and soil solutions using carbon fiber electrode

Analysis of trace level metals in environmental samples (e.g., soil, water, and plant samples) is important for assessing environmental quality and food safety. This paper reports a non-toxic, eco-friendly, and cost-effective sensing method, capable of in-situ detection of microgram per liter (µg/L) levels of heavy metal ions in plant and soil solutions using carbon fiber electrodes (CFEs) produced without using any microfabrication. The electrochemical behaviors of the CFEs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. As proof of principle, the CFEs were validated for sensing selected heavy metals in buffer solutions as well as in extracted plant and soil solutions using differential pulse anodic stripping voltammetry (DP-ASV). Experimental results confirm that the CFEs were able to simultaneously measure cadmium (Cd), lead (Pb), and mercury (Hg) with a detection limit of 2.10, 0.93, and 1.85 µg/L respectively in buffer solution, showcasing good selectivity and sensitivity. The ideal pH range for heavy metal detection was also extensively investigated and was found to be between pH 4.0 and pH 5.0. These findings lay a better foundation towards long-term and stable electrochemical analysis for plant and soil solution matrices.

Didactic experiment for voltametric determination the complexing capacity of natural waters

The titration method can be applied to determine the complexation capacity between metal ions and ligands in natural water samples. The process involves the incremental addition of the metal to the sample containing a specific ligand, resulting in a titration curve that reflects the formation of complexes. The change in the curves slope indicates the saturation of the complexation capacity. In this study, the copper (II) ion was used due to its stability with organic ligands. The titration curve was analyzed to determine the complexation capacity (CC) and conditional formation constant (K) of the complex. Different mathematical treatments are proposed for this analysis. In the described experiment, differential pulse anodic stripping voltammetry was used to determine the complexation capacity of humic substances in natural waters. Experimental parameters such as pH, supporting electrolyte concentration, and volume of additions were previously optimized for the voltammetry technique. The obtained data were processed and analyzed, resulting in titration curves and voltammograms. The analysis of the curves allowed for the calculation of the complexation capacity and conditional stability constant of the formed complex. The results demonstrate the feasibility of the method as a didactic experiment for the voltammetric determination of natural water complexation capacity.

Decentralized touch-based micronutrition sensor towards personalized nutrition: Parallel detection of sweat ascorbic acid and zinc ions

The zinc (Zn) and ascorbic acid (AA) micronutrient duo has received a considerable attention in individual’s nutrition plans, particularly after the recent pandemic, owing to its distinct beneficial impact on boosting the immune system. Accordingly, there are growing needs for frequent and decentralized measurements of the trace element and micronutrient levels towards well-balanced personalized nutrition. Leveraging natural sweat sampling from the fingertip, we describe here a disposable electrochemical sensor array, consisting of neighboring Zn ion (Zn(II)), and AA electrodes, towards parallel touch-based on-site monitoring of dynamically-changing sweat Zn(II), and AA levels, following the intake of the corresponding nutrition supplements.. A highly permeable poly (vinyl alcohol) (PVA) hydrogel, placed on the dual-electrode sensor array, served for transferring the sweat from the fingertip onto the electrode surface. Zn(II) measurements were performed on a bismuth/Nafion modified screen printed electrode (SPE) with square-wave anodic stripping voltammetry (SWASV), while the AA detection relied on recording of the open circuit potential (OCP) change, on the tetrathiafulvalene-7,7,8,8-tetracyanoquinodimethane (TTF-TCNQ) immobilized SPE. Rapid decentralized measurements of sweat Zn(II) and AA temporal profiles were carried out on the fingertip sweat of healthy subjects after consuming pill supplements in connection to the disposable strip along with hand-held electrochemical analyzer. The utility of the touch-based disposable Zn(II)/AA multisensory platform for parallel measurements of this pair of micronutrients was demonstrated towards personalized nutrition by providing real-time monitoring of the dose-response relationship. Our findings indicate that the new sweat nutrition sensing device holds considerable promise for guiding dietary interventions and enhancing personalized nutrition.

Anodic Stripping Voltammetric Procedure of Thallium(I) Determination by Means of a Bismuth-Plated Gold-Based Microelectrode Array.

This article presents a new working electrode based on a bismuth-plated, gold-based microelectrode array, which is suitable for determining thallium(I) species using anodic stripping voltammetry (ASV). It allowed a significant increase in the sensitivity as compared to other voltammetric sensors. The main experimental conditions and the instrumental parameters were optimized. A very good proportionality between the Tl(I) peak current and its concentration was evidenced in the range from 5 × 10-10 up to 5 × 10-7 mol L-1 (R = 0.9989) for 120 s of deposition and from 2 × 10-10 up to 2 × 10-7 mol L-1 (R = 0.9988) for 180 s. A limit of detection (LOD) of 8 × 10-11 mol L-1 for a deposition time of 180 s was calculated. The effects of interfering ions on the Tl(I) analytical signal were studied. The proposed method was applied for quantitative Tl(I) detection in water certified reference material TM 25.5 as well as in spiked real water samples, for which satisfactory recovery values between 98.7 and 101.8% were determined.