Nanomolar determination of Pb (II) ions by selective templated electrode

Polypyrrole modified electrode, prepared by electropolymerization of pyrrole in the presence of methyl red as a dopant, was templated with respect to Pb2+ ion and applied for potentiometric and voltammetric detection of this ion. The templating process improved the analytical response characteristics of the electrode, specially their selectivity, with respect to Pb2+ ion. The improvement depends on both the incorporated ligand (dopant) and the templating process, with the latter being more vital. The potentiometric response of the electrode was linear within the Pb2+ concentration range of 2.0?10-6 to 5.0?10-2 M with a near-Nernstian slope of 28.6 mV decade-1 and a detection limit of 7.0 ?10-7 M. The electrode was also used for preconcentration differential pulse anodic stripping voltammetry (DPASV) and results showed that peak currents for the incorporated lead species were dependent on the metal ion concentration in the range of 1.0?10-8 to 1.0?10-3 M. The detection limit of DPASV method was 3.5 ?10-9 M. The selectivity of the electrode with respect to some transition metal ions was investigated. The modified-templated electrode was used for the successful assay of lead in two standard reference material samples.

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Copper Complexing Capacity and Trace Metal Content in Common and Balsamic Vinegars: Impact of Organic Matter

Molecules ◽

10.3390/molecules25040861 ◽

2020 ◽

Vol 25 (4) ◽

pp. 861

Author(s):

Sotirios Karavoltsos ◽

Aikaterini Sakellari ◽

Vassilia J. Sinanoglou ◽

Panagiotis Zoumpoulakis ◽

Marta Plavšić ◽

...

Keyword(s):

Organic Matter ◽

Metal Ions ◽

Metal Ion ◽

Metal Speciation ◽

Anodic Stripping Voltammetry ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Transition Metal Ions ◽

Electrochemical Technique ◽

Mass Unit

Complex formation is among the mechanisms affecting metal bioaccessibility. Hence, the quantification of organic metal complexation in food items is of interest. Organic ligands in solutions of environmental and/or food origin function as buffering agents against small changes in dissolved metal concentrations, being able to maintain free metal ion concentrations below the toxicity threshold. Organic matter in vinegars consists of bioactive compounds, such as polyphenols, Maillard reaction endproducts, etc., capable of complexing metal ions. Furthermore, transition metal ions are considered as micronutrients essential for living organisms exerting a crucial role in metabolic processes. In this study, differential pulse anodic stripping voltammetry (DPASV), a sensitive electrochemical technique considered to be a powerful tool for the study of metal speciation, was applied for the first time in vinegar samples. The concentrations of Cu complexing ligands (LT) in 43 vinegars retailed in Greece varied between 0.05 and 52 μM, with the highest median concentration determined in balsamic vinegars (14 μM), compared to that of common vinegars (0.86 μM). In 21% of the vinegar samples examined, LT values were exceeded by the corresponding total Cu concentrations, indicating the presence of free Cu ion and/or bound within labile inorganic/organic complexes. Red grape balsamic vinegars exhibited the highest density of Cu ligands per mass unit of organic matter compared to other foodstuffs such as herbal infusions, coffee brews, and beers. Among the 16 metals determined in vinegars, Pb is of particular importance from a toxicological point of view, whereas further investigation is required regarding potential Rb biomagnification.

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The use of differential pulse anodic stripping voltammetry and diffusive gradient in thin films for heavy metals speciation in soil solution

Open Chemistry ◽

10.2478/s11532-007-0060-6 ◽

2008 ◽

Vol 6 (1) ◽

pp. 71-79 ◽

Cited By ~ 7

Author(s):

Jana Dytrtová ◽

Ivana Šestáková ◽

Michal Jakl ◽

Jiřina Száková ◽

Daniela Miholová ◽

...

Keyword(s):

Thin Films ◽

Heavy Metals ◽

Soil Solution ◽

Metal Ion ◽

Plant Biomass ◽

Anodic Stripping Voltammetry ◽

Total Content ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Anodic Stripping

AbstractIn the soil solutions obtained in situ with suction cups from soils (Cambisol and Fluvisol) of pot experiment with Salix smithiana Smith, Lolium perenne L. and Thlaspi caerulescens J. & C. Presl heavy metals species (Cd, Pb and Cu) were assayed by differential pulse anodic stripping voltammetry and diffusive gradient in thin films. Prediction of accumulation performed best at free metal ion concentrations in unchanged pH (in 10−3 mol L−1 NaClO4 base electrolyte). The speciation provided by differential pulse anodic stripping voltammetry according to pH can provide a detailed description of the soil solution matrix. The concentration of free metals in unchanged pH represents a small part of the total content and varied from 0.04 to 0.75% with two exceptions found for accumulating plants (the content of Cd2+ in the soil solution from T. caerulescens was about 6% and the content of Cu2+ in the soil solution from S. smithiana was about 30%). The available concentration as determined by diffusive gradient in thin films was not in correlation with the heavy metals concentration in plant biomass.

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Polysulfide/Graphene Nanocomposite Film for Simultaneous Electrochemical Determination of Cadmium and Lead Ions

NANO ◽

10.1142/s179329201850090x ◽

2018 ◽

Vol 13 (08) ◽

pp. 1850090 ◽

Cited By ~ 4

Author(s):

Ruyuan Jiang ◽

Niantao Liu ◽

Yuhong Su ◽

Sanshuang Gao ◽

Xamxikamar Mamat ◽

...

Keyword(s):

Electron Microscopy ◽

Heavy Metal ◽

Photoelectron Spectroscopy ◽

Metal Ion ◽

Electrochemical Sensors ◽

Anodic Stripping Voltammetry ◽

Pyrolytic Graphite ◽

Stripping Voltammetry ◽

Ion Concentration ◽

X Ray

An integrative electroanalytical method was developed for detecting Cd[Formula: see text] and Pb[Formula: see text] ions in aqueous solutions. Polysulfide/graphene (RGO-S) nanocomposites were prepared and their performance as electrochemical sensors for Cd[Formula: see text] and Pb[Formula: see text] was evaluated. The RGO-S nanocomposite was carefully characterized by scanning electron microscopy with energy-dispersive X-ray spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy. The as-prepared RGO-S was incorporated into a pyrolytic graphite electrode (RGO-S/PGE) and used for detecting trace amount of Cd[Formula: see text] and Pb[Formula: see text] by differential pulse anodic stripping voltammetry. Under optimal conditions, the stripping peak current of RGO-S/PGE varies linearly with heavy metal ion concentration in the ranges 2.0–300[Formula: see text][Formula: see text]g L[Formula: see text] for Cd[Formula: see text] and 1.0–300[Formula: see text][Formula: see text]g L[Formula: see text] for Pb[Formula: see text]. The limits of detection for Cd[Formula: see text] and Pb[Formula: see text] were estimated to be about 0.67[Formula: see text][Formula: see text]g L[Formula: see text] and 0.17[Formula: see text][Formula: see text]g L[Formula: see text], respectively. The prepared electrochemical heavy-metal-detecting electrode provides good repeatability and reproducibility with high sensitivity, making it a suitable candidate for monitoring Cd[Formula: see text] and Pb[Formula: see text] concentrations in aqueous environmental samples.

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Determination of Trace Metal Ions in Common Salt by Stripping Voltammetry

Journal of AOAC International ◽

10.1093/jaoac/82.6.1413 ◽

1999 ◽

Vol 82 (6) ◽

pp. 1413-1418 ◽

Cited By ~ 6

Author(s):

Azza M M Ali

Keyword(s):

Metal Ion ◽

Supporting Electrolyte ◽

Standard Addition ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Ion Concentration ◽

Common Salt ◽

Trace Metal Ions

Abstract Sensitive voltammetric methods using cathodic and anodic differential pulse stripping techniques were applied for determination of trace ions cadmium(II), cobalt(II), copper(II), lead(II), manganese(II), nickel(II), and zinc(II), which are usually found in different grades of common salt as contaminants. The optimal conditions, i.e., deposition time, preconcentration potential, supporting electrolyte, and ionic strength, were investigated for each metal ion. Concentration of the metal ion was determined by the standard addition method. Metal content varied according to the quality of the table salt.

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Direct measurement of equilibrium constants for water-soluble porphyrin with copper(II) and cobalt(II) by differential pulse anodic stripping voltammetry (DPASV)

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424612004550 ◽

2012 ◽

Vol 16 (02) ◽

pp. 235-243

Author(s):

Md. Shahajahan Kutubi ◽

Masaaki Tabata

Keyword(s):

Detection Limit ◽

Metal Ions ◽

Stability Constants ◽

Anodic Stripping Voltammetry ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Water Soluble ◽

Working Electrode ◽

Anodic Stripping ◽

The Stability

Because of high stability constants and slow metalation rate of porphyrins, it is difficult to determine stability constants of metalloporphyrins correctly. We propose here a new method for the determination of the stability constant of Cu(II) or Co(II) with 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, H2(OBTMPyP(4))4+ , by differential pulse anodic stripping voltammetry (DPASV) using a gold working electrode. The concentrations of free Cu(II) or Co(II) ion as low as 10-7–10-8 M were determined directly in equilibrium with H2(OBTMPyP(4))4+ of 10-7–10-8 M under optimum DPSAV conditions of rotating disk gold electrode, deposition of metals, stripping of metals, potential pulse amplitude and pulse width. Furthermore effects of supporting electrolytes, time for the attainment of chemical equilibrium and determination methods (standard addition and calibration curve methods) of total free metal ions were considered. Tetramethylammonium chloride, (CH3)4N+Cl-(TMAC) , showed the lowest detection limit of metals among other electrolytes such as Na2SO4 , NaNO3 , NaCl : 0.5 ppb for Cu(II) at I = 0.1 ((CH3)4N+Cl-) . The stability constants of K s defined as M2+ + P2- = MP ( M = Cu(II) and Co(II) , and H2P = H2(OBTMPyP(4))4+ ) were 1013.93 and 109.47 M-1 for Cu(II) and Co(II) , respectively, at I = 0.1 (CH3)4N+Cl-) and 25 °C. The working electrode was also electrochemically activated at higher potential affording to lower detection limit of metal ions as well as to measure cyclic voltammetry of metal ions, porphyrin and metalloporphyrin as low as 10-5 M. The values of E ap (vs. Ag/AgCl ) of Cu2+ , H2(OBTMPyP(4))4+ and Cu(OBTMPyP(4))4+ were 345, 338 and 425, respectively.

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Voltammetric Detection of Tetrodotoxin Real-Time In Vivo of Mouse Organs using DNA-Immobilized Carbon Nanotube Sensors

Current Analytical Chemistry ◽

10.2174/1573411014666180510145320 ◽

2019 ◽

Vol 15 (5) ◽

pp. 567-574

Author(s):

Huck Jun Hong ◽

Suw Young Ly

Keyword(s):

Carbon Nanotube ◽

Real Time ◽

Anticancer Agents ◽

Cancer Metastasis ◽

Anodic Stripping Voltammetry ◽

Stripping Voltammetry ◽

Takifugu Rubripes ◽

In Vivo Detection ◽

Voltammetric Detection

Background: Tetrodotoxin (TTX) is a biosynthesized neurotoxin that exhibits powerful anticancer and analgesic abilities by inhibiting voltage-gated sodium channels that are crucial for cancer metastasis and pain delivery. However, for the toxin’s future medical applications to come true, accurate, inexpensive, and real-time in vivo detection of TTX remains as a fundamental step. Methods: In this study, highly purified TTX extracted from organs of Takifugu rubripes was injected and detected in vivo of mouse organs (liver, heart, and intestines) using Cyclic Voltammetry (CV) and Square Wave Anodic Stripping Voltammetry (SWASV) for the first time. In vivo detection of TTX was performed with auxiliary, reference, and working herring sperm DNA-immobilized carbon nanotube sensor systems. Results: DNA-immobilization and optimization of amplitude (V), stripping time (sec), increment (mV), and frequency (Hz) parameters for utilized sensors amplified detected peak currents, while highly sensitive in vivo detection limits, 3.43 µg L-1 for CV and 1.21 µg L-1 for SWASV, were attained. Developed sensors herein were confirmed to be more sensitive and selective than conventional graphite rodelectrodes modified likewise. A linear relationship was observed between injected TTX concentration and anodic spike peak height. Microscopic examination displayed coagulation and abnormalities in mouse organs, confirming the powerful neurotoxicity of extracted TTX. Conclusion: These results established the diagnostic measures for TTX detection regarding in vivo application of neurotoxin-deviated anticancer agents and analgesics, as well as TTX from food poisoning and environmental contamination.

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Potentiometric Carboxylate Sensors Based on Carbazole-Derived Acyclic and Macrocyclic Ionophores

Chemosensors ◽

10.3390/chemosensors9010004 ◽

2020 ◽

Vol 9 (1) ◽

pp. 4

Author(s):

Ville Yrjänä ◽

Indrek Saar ◽

Mihkel Ilisson ◽

Sandip A. Kadam ◽

Ivo Leito ◽

...

Keyword(s):

Detection Limit ◽

Vinyl Chloride ◽

Anion Exchanger ◽

Linear Range ◽

Ph Sensitivity ◽

Ion Selective Electrodes ◽

Solid Contact ◽

Response Characteristics ◽

Potentiometric Response ◽

Poly Vinyl Chloride

Solid-contact ion-selective electrodes with carbazole-derived ionophores were prepared. They were characterized as acetate sensors, but can be used to determine a number of carboxylates. The potentiometric response characteristics (slope, detection limit, selectivity, and pH sensitivity) of sensors prepared with different membrane compositions (ionophore, ionophore concentration, anion exchanger concentration, and plasticizer) were evaluated. The results show that for the macrocyclic ionophores, a larger cavity provided better selectivity. The sensors exhibited modest selectivity for acetate but good selectivity for benzoate. The carbazole-derived ionophores effectively decreased the interference from lipophilic anions, such as bromide, nitrate, iodide, and thiocyanate. The selectivity, detection limit, and linear range were improved by choosing a suitable plasticizer and by reducing the ionophore and anion exchanger concentrations. The influence of the electrode body’s material upon the composition of the plasticized poly(vinyl chloride) membrane, and thus also upon the sensor characteristics, was also studied. The choice of materials for the electrode body significantly affected the characteristics of the sensors.

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