Potentiometric Stripping Analysis Research Articles

Electrochemical immunoassay for one-pot detection of thyroxin (T4) and thyroid-stimulating hormone (TSH) using magnetic and Janus nanoparticles.

Concurrent measurement ofthyroid-stimulating hormone (TSH) and thyroxine (T4) hormones profoundly help clinicians diagnose hyper- and hypothyroidism. This work demonstrates the development of a sandwich-type electrochemical immunoassay using Janus and magnetic nanoparticles for one-pot detection of thyroxine (T4) and thyroid-stimulating hormone (TSH). The signaling probe was developed by preparing Janus cadmium (CdO) and zinc oxide (ZnO) NPs decorated by T4/TSH-specific molecularly imprinted polymers (MIPT4-CdO and MIPTSH-ZnO). The capture probe was obtained by coating magnetic Fe3O4 NPs with 1,3-Bis(3-carboxy propyl) tetramethyl disiloxane and activating using N-hydroxy succinimide (NHS) and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC), and finally conjugating with T4/TSH-specific antibodies. To analyze T4 and TSH in actual samples, MIPT4-CdO and MIPTSH-ZnO were added to the sample solutions, and after incubation, capture probes (Fe3O4-AbTSH and Fe3O4-AbT4) were added. An external magnetic field was used to separate the sandwiched nanosystem, followed by adding a dilute solution of nitric acid (HNO3) to dissolve CdO and ZnO NPs and free Cd(II) and Zn(II) cations. The concentration of these cations was determined using constant-current potentiometric stripping analysis (cc-PSA) on screen-printed electrodes (SPE) modified with multi-walled carbon nanotubes (MWCNT). The obtained signals for Cd(II) and Zn(II) were proportional to T4 and TSH concentrations. Limits of detection (LOD) for T4 and TSH analyses were respectively 0.02ng.dL-1 and 0.0002 µU.mL-1 with a linear range of 0.05-50ng.dL-1 and 0.001-100 µU.mL-1. The proposed nanosystem's main advantage is the simultaneous detection of T4 and TSH in clinical samples with high sensitivity, selectivity, and stability.

Metal‐free phthalimide‐labeled peptide nucleic acids for electrochemical biosensing applications

AbstractPeptide nucleic acids (PNAs) are neutral mimics of natural DNA and RNA biopolymers that have caught the attention of researchers working on the identification of specific sequences of nucleobases in DNA/RNA strands. For this purpose, specific analytical protocols need to be developed to optimize the nucleic acid recognition ability of PNAs, exploiting both the high intrinsic affinity of PNA/DNA(RNA) couples as well as suitable markers, either linked to the PNA backbone or properly interacting with it in the working medium. In this context, the paper reports on phthalimide and 4‐nitrophthalimide as two cheap, metal‐free electroactive markers covalently bound to the pseudo‐peptide backbone of a PNA decamer. After a preliminary characterization of the markers, as such and in PNA conjugates, attention has been moved toward the optimization of the detectability of the labeled PNA decamers in aqueous solutions. Exploiting the potentiometric stripping analysis on hanging mercury drop electrode it has been possible to reach satisfactory detection limits of ca. 10 nM avoiding the use of expensive transition metal complexes as labels and/or of co‐reagents.

Effects of the variation of diffusion coefficients in the potentiometric stripping analysis

AbstractA simple steady state model of potentiometric stripping analysis and its derivative mode that are influenced by the film of adsorbed substance that hinders the diffusion of oxidant and metal ions is developed. The dependence of stripping time and the maximum in the derivative mode on the degree of inhibition is calculated. The responses are enhanced if the flux of oxidant is diminished.

Novel Type of Carbon Nanotube Paste Electrode Modified by Sb2O3 for Square Wave Anodic Stripping Voltammetric Determination of Cd2+ and Pb2+

AbstractA novel type of carbon paste electrode modified by multi‐walled carbon nanotubes and antimony trioxide (Sb2O3/CNTCPE) was applied for square wave anodic stripping voltammetry (SWASV) of Cd2+ and Pb2+. Important parameters (deposition potential, deposition time, HCl concentration) were optimized and linear concentration dependence was obtained in the range of 10–100 ppb with LOD 1.7 ppb for Cd2+ and 1.2 ppb for Pb2+. The practical applicability was tested on the determination of Cd2+ and Pb2+ in tap water. The potentiometric stripping analysis at Sb2O3/CNTCPE was tested for the determination of Cd2+ and Pb2+ to compare this method with SWASV.

Optimization and Application of Potentiometric Stripping Analysis for Determination of Heavy Metals in the samples of Aronia melanocarpa (Michx.) Elliot

Optimization and Application of Potentiometric Stripping Analysis for Determination of Heavy Metals in the samples of Aronia melanocarpa (Michx.) Elliot

Potentiometric Stripping Analysis of Cadmium and Lead with Constant Inverse Current in the Analytical Step Using an Open Tubular Mercury-Coated Glassy Carbon Electrode

The most important experimental parameters of the flow potentiometric stripping analysis (PSA) with oxygen as an oxidant were investigated and optimised. A simple, homemade flow system consisting of glassy carbon tubes, which served as a working and auxiliary electrode, was used. By applying a rest period before the stripping step (the flow stop mode) and by imposing a constant reductive current simultaneously with the interruption of potentiostatic control, significant increase of the flow PSA sensitivity was achieved. In the determination of cadmium and lead, quantitation limits of 0.11 and 0.82 μg/L were obtained. The precision of the method was evaluated in terms of repeatability and reproducibility, with values of relative standard deviation lower than 4.0% for cadmium and 4.2% for lead. This modified technique was applied for simultaneous determination of cadmium and lead in milk, after a simple pretreatment of the samples by dilution and acidification. The method accuracy was confirmed by analysing the certified reference material of skimmed milk powder (ERM-BD151).

Analysis and simulation of bioaccumulation of selected metals from contaminated soil

The aim of this study was: I) to determine Pb, Cd and Zn concentrations in alluvial soil before and after planting selected plant species, and II) modeling of the bioaccumulation process in the examined soil, using several plant species. Soil samples were collected from the northern part of Kosovo and Metohija, and the selected plants were: a) vegetables: Lactuca sativa L. and Allium cepa L.; b) legumes: Lotus corniculatus L. and Trifolium pratense L.; and c) grasses (weed plants): Cynodon dactylon (L.) Pers. and Festuca arundinaceae Schreb. The experimental part of the work was carried out by vegetation experiments, and heavy metal concentrations were determined by potentiometric stripping analysis (PSA). The obtained results show that: I) the heavy metal concentrations in the analyzed soil were above allowed values at all measuring points; II) the selected species accumulated heavy metals to some extent. Expressed in percentages, vegetables and legumes accumulated 9?11 % Pb, 12?33 % Cd and 11?19 % Zn. Cyndon dactylon Pers. accumulated about 69 % Pb, 24?40 % Cd and 43 % Zn. Festuca arundinaceae accumulated 39?40 % Zn, 58?81 % Cd, and Pb up to 70 %. The obtained results indicate high tolerance to heavy metals, especially in the case of Festuca arundinacea. By simulation of the bioaccumulation process it has been established that the dependence of the concentration of metal ions before and after planting represents a linear regression. Coefficients of the model, for the discussed cases of heavy metals and plant species, were determined by minimization of the mean square error, and quality of model fits was evaluated by the values of the statistical indicators the RSE (Residual Standard Error) and MRE (Mean Relative Error). The closer the values of these indicators are to zero, the more accurate the model is. It can be concluded that the adopted model describes sufficiently well the dependence of concentrations of Pb and Zn in the soil before and after planting. The mean relative error (MRE) in the case of Cd is slightly higher than 7 %, which suggests that the use of a non-linear model is needed for which it is necessary to have additional samples available, which can be the subject of further research.

Labile lead phytochelatin complex could enhance transport of lead ions across biological membrane

In connection with studies of transport of hazardous metals across model phospholipid membranes (PLMs), behavior of complexes of lead with phytochelatin PC2 has been examined. Using differential potentiometric stripping analysis (PSA, Chronopotentiometry) with different values of constant negative current, the release of free lead ions confirmed their labile behavior. Similar conclusion resulted from voltammetry on silica gel modified carbon paste electrode. Diffusion controlled transport across a PLMs containing ionophore calcimycin (A23187) revealed 26 times more lead ions transported in case of Pb-phytochelatin complexes than in case of free lead ions. For labile behavior, complex with two Pb atoms at phytochelatin molecule is responsible.

Determination of heavy metals in soil and biomass by the application of potentiometric stripping analysis

In this paper the determination of lead, cadmium and zinc in soil and biomass was performed using potentiometric stripping analysis (PSA). In order to establish the optimal experimental conditions for PSA of Pb, Cd and Zn, the influence of pH value, time of metals extraction, stirring rate of the solution and the thickness of the mercury layer, as the working electrode, was investigated. The influence of mentioned parameters was tested for individual and simultaneous metals determination. The achieved limits of determination of single ions were for: lead 22.5 μg dm-3, cadmium 16.2 μg dm-3 and zinc 18.8 μg dm-3. The obtained results deviated from the expected for 1.1%, 1.9% and 1.8%, for lead, cadmium and zinc, respectively. For simultaneous determination, the method is tested using the ions contents as follows: 45.0 μg dm-3 for lead, 32.5 μg dm-3 for cadmium and 37.5 μg dm-3 for zinc. The relative errors for simultaneous determination were: 4.6% for lead, 1.9% for cadmium and 1.9% for zinc. For the established optimal conditions, except for lead, deviations did not exceed ±2%. It is shown that potentiometric stripping analysis is usable for individual and simultaneous determination of lead, cadmium and zinc in soil and biomass.

Development and application of potentiometric stripping analysis

This paper focuses on the voltammetric determination of lead, cadmium and zinc in water. Two ways of determining were investigated: individually and all three metals simultaneously. The experiments were performed using the Potentiometric Stripping Analysis (PSA). Determination of metals in real samples was preceded by preliminary tests. Preliminary investigations were performed in order to determine the optimal conditions of measurement. It was concluded that the process of determining was for most part influenced by: pH, time of metals extraction, stirring rate of the solution and the thickness of the mercury layer on the working electrode. The smallest concentrations of metals which can be determined using this method are: for lead 22.48 μg dm-3, for cadmium 16.23 μg dm-3 and for zinc 18.75 μg dm-3. The obtained results deviated from the actual 1.12% for lead, 1.91% for cadmium and 1.81% for zinc. All tests (individually and simultaneously) were conducted from model solution with concentration as follows: 44.96 μg dm-3 for lead, 32.47 μg dm-3 for cadmium and 37.50 μg dm-3 for zinc. The results of individual measurements deviated by 1.02% lead, 1.90% for cadmium and 1.89% for zinc. Simultaneously the contents were lower than real for: -4.58% for lead, cadmium for -1.91% and -1.89% for zinc. For the conditions determined, except for lead, deviations did not exceed ±2% . This indicates that Potentiometric Stripping Analysis is a good way of individual and simultaneous determination of lead, cadmium and zinc and for determination of their concentrations in water (river and groundwater).

Heavy Metals in Soil and Application of New Plant Materials in the Process of Phytoremediation

The aim of this paper is to determine the concentration of Pb, Cd, and Zn in: I) alluvial soil; and II) plants: a) vegetable: lettuce (Lactuca sativa) and common onion (Allium cepa); b) legumes: bird's- foot trefoil (Lotus corniculatus L.) and red clover (Trifolium pretense L.); and c) grasses (weed plants): zubach (Cynodon dactylon) and tall fescue (Festuca arundinaceous Schreb.); as well as III) determination of new plant species suitable for bioaccumulation and phytoremediation processes. The experimental work was carried out through vegetation experiments, and the concentration of metal was determined by potentiometric stripping analysis (PSA). The obtained results show that: I) the concentration of metals in the analyzed soil is above the allowed values at all measuring points; II) a) concentration of Cd in leaf and Pb at the root of the lettuce is increased; b) the concentration of the metal in the bird's-foot trefoil and the red clover is lower than the critical value for the plants; c) in grasses (weed plants), tall fescue and couch grass, the concentration of metal is higher than critical in all measuring points, and in some places it has a value that is toxic for plants; and e) weed plants: tall fescue and couch grass contain high concentrations of heavy metals indicating a certain degree of tolerance and the possibility of using these plants in the bioaccumulation and phytoremediation process.

A Study of the Possible Harmful Effects of Cosmetic Beauty Products on Human Health.

The origins of the usage of different substances in beauty, skin, body, hair, and nails care products can be found in ancient times. To achieve better quality and enhance their effects, some additives such as preservatives, stabilizers, mineral pigments, dye, and shine were added to these products. Some of these substances may also have allergic, irritating, and harmful effects on human health. The aim of this study was the optimization of the potentiometric stripping analysis (PSA) for the purpose of determining the content of heavy metals (lead, cadmium, zinc), in some commercial cosmetic beauty products (lipsticks, lip glosses, eye shadows, and henna hair dye). In addition, in order to monitor the potential adverse effects of henna dye on hair quality, as well as the total body burden of heavy metals (Pb, Cd), the paper analyzed hair samples before and after henna dye treatment. Beauty products used for cosmetic purposes can have adverse effects to human health due to the fact that they contain lead, a highly toxic metal. The lead content in the tested samples varied depending on the additives used along with the method of production. The cosmetic products that were analyzed in this study contained a certain amount of zinc, which is an essential element, although its content above the prescribed limit may lead to side effects. Highly toxic metal, cadmium, was not detected in the tested samples. The presence of these metals in cosmetic products certainly indicate that it is necessary to monitor and determinate the content of toxic heavy metals in these products, especially because they are in direct contact with skin or mucous membranes and are often used in daily life.

Potentiometric stripping analysis of arsenic using a graphene paste electrode modified with a thiacrown ether and gold nanoparticles

An electrochemical method is presented for the determination of arsenic at subnanomolar levels. It is based on potentiometric stripping analysis (PSA) using a graphene paste electrode modified with the thiacrown 1,4,7-trithiacyclononane (TTCN) and gold nanoparticles (AuNPs). The electrode surface was characterized by means of cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and scanning electron microscopy. The modified electrode displays a 15-fold enhancement in the PSA signal (dt/dE) compared to a conventional graphene paste electrode. Under optimized conditions, the signal is proportional to the concentration of As(III) in the range from 25 pM to 34 nM (r2 = 0.9977), and the detection limit (SD/s) is as low as 8 pM. The modified electrode was successfully applied to the determination of total arsenic [i.e., As(III) and As(V)] in pharmaceutical formulations, human hair, sea water, fruits, vegetables, soil, and wine samples.

Direct Determination of Heavy Metals in Honey by Potentiometric Stripping Analysis

Direct Determination of Heavy Metals in Honey by Potentiometric Stripping Analysis

Bioavailability of heavy metals in the soil from different locations of medicinal herbs

SUMMARY Medicinal herbs and their mixtures, which are widely used for prevention and treatment of some disease, can also present health risks due to the presence of toxic metals such as Pb and Cd. The application of different agrotechnical practices during plant growing season, as well as the process of circulation of substances in nature, may be the cause of plant contamination. The aim of this study was to determine the content of lead, cadmium and copper from soil which are bioavailable for absorption by plant, as well as the total content of these metals in some medicinal herbs that were cultivated in two different locations. The presence of these metals in the samples was detected using highly sensitive microanalytical technique potentiometric stripping analysis (PSA). The mean value of lead total content in the analyzed samples of medicinal herbs Chamimillae flos, Urticae folium, Menthae folium, Altheae radix and Basilici herba, which were grown at the sites near the industrial zone, was about 1.55 μg/g, 1.82 μg/g, 1.90 μg/g, 1.99 μg/g and 2.74 μg/g, respectively. Contrary to this, the total content of this toxic metal in the analyzed plant samples grown on rural areas was detected only on some sites. Based on the results of this study, it can be concluded that medicinal herbs contained a certain amount of lead and that its content varied depending on the location at which the plant species were grown as well as on plant affinity to certain metal. Cadmium and copper were not detected in the tested plant material.

Determination of heavy metals in milk and fermented milk products by potentiometric stripping analysis with constant inverse current in the analytical step

A simple and rapid method for the direct determination of cadmium, lead and copper in milk and fermented milk products by potentiometric stripping analysis (PSA) with oxygen as an oxidant and with inverse current imposed through the stripping step is described. For the more selective metals determination a samples pretreatment by the microwave acid extraction was applied. Due to the significant increase of the modified technique sensitivity, the detection limits of 0.30, 1.7 and 3.8μg/l were obtained, for cadmium, lead and copper, respectively. The method accuracy was confirmed by analysing the standard reference material (SRM 1577b). The contents of cadmium, lead and copper in milk samples were in the range of 2.13–4.82, 54.3–95.2 and 112.2–124.7μg/kg, respectively, whereas in the samples of fermented milk products in the range of 6.30–24.1, 210.1–463.6 and 260.0–320.7μg/kg, respectively.

ENG

This study was to determine the feasibility of using potentiometric stripping analysis (PSA) to measure serum levels of copper, lead, and zinc in elderly subjects with metabolic disorders (hyperglycemia, hypertriglyceridemia, and hypercholesterolemia). Furthermore, we investigated the relationship between serum trace elements and lipid and glucose levels in these patients. There was a strong correlation between serum copper and lead levels in all subjects. Copper levels were significantly higher in subjects with elevated triglycerides and cholesterol, but not blood sugar. Serum zinc concentrations were elevated in hyperglycemic subjects, suggesting a correlation between blood sugar and serum zinc levels. Patients with increased levels of lead and copper, but decreased levels of zinc, had hypertriglyceridemia or hypercholesterolemia. Patients with high levels of zinc, but low levels of lead and copper, were hyperglycemic. These results showed that serum copper and lead levels have important diagnostic value for assessing metabolic disorder and related disease.<br/> These methods presented here were applicable for the cause of death diagnosis in medico-legal autopsy.

Theory and Verify of Mensurate Cl&lt;sup&gt;-&lt;/sup&gt; Ion by Flow Injection-Cathodic Potentiometric Stripping Analysis

In this paper, the theoretical equation of flow injection-cathodic potentiometric stripping analysis for Cl-ion determination was derived from theoretical analysis, and the experimental equation was summarized using multiple linear regression method. The result shows that the theoretical equation of flow injection-cathodic potentiometric stripping analysis for Cl-ion is: (dt/dE)max=K Apr-1/2D2/3-1/6Vf1/2teCx-/is;that the experimental equation of multiple linear regression method is: (dt/dE)max Cl-1.86×1010Vf0.568teCCl-/is. The two results are similar on Vf-average flow rate, te-concentrate time, CCl--Cl-ion concentration and isconstant current.

Derivative Potentiometric Stripping Analysis of Cu (II) at Nanomolar Levels Exploiting the 4-[10,15,20-tris (4-sulfophenyl)-21,22-dihydroporphyrin-5-yl] Benzenesulfonic Acid Host Compound on Multi-Walled Carbon Nanotubes

Derivative Potentiometric Stripping Analysis of Cu (II) at Nanomolar Levels Exploiting the 4-[10,15,20-tris (4-sulfophenyl)-21,22-dihydroporphyrin-5-yl] Benzenesulfonic Acid Host Compound on Multi-Walled Carbon Nanotubes

A clinical study of the effects of lead poisoning on the intelligence and neurobehavioral abilities of children

BackgroundLead is a heavy metal and important environmental toxicant and nerve poison that can destruction many functions of the nervous system. Lead poisoning is a medical condition caused by increased levels of lead in the body. Lead interferes with a variety of body processes and is toxic to many organs and issues, including the central nervous system. It interferes with the development of the nervous system, and is therefore particularly toxic to children, causing potentially permanent neural and cognitive impairments. In this study, we investigated the relationship between lead poisoning and the intellectual and neurobehavioral capabilities of children.MethodsThe background characteristics of the research subjects were collected by questionnaire survey. Blood lead levels were detected by differential potentiometric stripping analysis (DPSA). Intelligence was assessed using the Gesell Developmental Scale. The Achenbach Child Behavior Checklist (CBCL) was used to evaluate each child’s behavior.ResultsBlood lead levels were significantly negatively correlated with the developmental quotients of adaptive behavior, gross motor performance, fine motor performance, language development, and individual social behavior (P < 0.01). Compared with healthy children, more children with lead poisoning had abnormal behaviors, especially social withdrawal, depression, and atypical body movements, aggressions and destruction.ConclusionLead poisoning has adverse effects on the behavior and mental development of 2–4-year-old children, prescribing positive and effective precautionary measures.