Potentiometric Stripping Analysis Research Articles

Sorption of lead, cadmium and zinc from air sediments applying natural wool fiber

The aim of this study is to investigate the possibilities of removing lead, cadmium, and zinc from air by sorption natural wool fibers (NWF), thus evaluating possible application of the wool materials in direct protection of air from the influence of heavy metals. Metal detection was done (before and after the sorption process) by potentiometric stripping analysis. Sorption experiments were done in two ways: by immersing NWF in model solutions (prepared by the working standard solutions and deionized water), and by immersing NWF in solutions of sediments from the air. The influence of mass sorbent, sorption time, pH, and temperature on the sorption of lead, cadmium, and zinc were experimentally examined. Effectiveness of lead, cadmium, and zinc sorption by applying natural wool fibers is shown as the sorption capacity (a ratio between metal concentration before and after sorption and sorbent mass). Sorbent of 0.1 g NWF mass in neutral environment collects: after 10 min 23,9% of lead, 19,0% of cadmium, and 21,3% of zinc; whereas after 30 min 71.5% of lead, 69.6% of cadmium, and 69.4% of zinc. NWF of the same mass in acidic environment shows lower sorption capabilities, for pH 4.5 the effective sorption is: 68.6% of lead, 66.8% of cadmium, and 66.6% of zinc; whereas for pH 2.1 NWF sorption is 54.6% of lead, 53.2% of cadmium, and 52.9% of zinc. Optimal pH range for application of this sorption during the experiment material is 4.5-7.0. The sorption was made in solutions with pH 2.1 due to potentiometric stripping analysis application conditions. Temperature significantly impacts the tested material sorption characteristics. When temperature slightly increases, regardless of the inflicted damage, NWF keeps its functionality. When temperature is higher than 60?C, the sorbent effectiveness is reduced. The NWF sorption capacity is lowest at 100?C: for lead 11.63 ?g g?1, for cadmium 8.18 ?g g?1, and for zinc 9.41 ?g g?1. Results of the experimental research have shown that a high degree of removal (about 70%) can be achieved provided that the mass of the sorbent rages from 0,06?0,1 g, contact time is long enough (30 min), and that there are no significant effects of temperature and pH.

The content of lead in herbal drugs and tea samples

AbstractHeavy metals are highly toxic to living organisms even in low concentrations owing to their cumulative effect. In this study the overall content of lead in herbal drugs was determined, as well as the content of lead which was released from tested drugs during the preparation of tea drinks. To determine the content of toxic lead, the highly sensitive microanalytical technique of the potentiometric stripping analysis (PSA) with oxygen as the oxidant was used. The lowest overall content of lead was detected for chamomile and ranged from 0.73 to 0.77 µg/g, while the greatest content of lead was determined in the samples of the frangula bark, and yielded approximately 3 µg/g. The lead content in the prepared tea drinks ranged from 0.26 to 1.23 µg/g and depended on the manner in which tea drink was prepared. All of the herbal drugs in this study contain a certain amount of the toxic metal lead, but at the same time, the contents were below the levels prescribed for this metal. The content of lead released from the herbal drug into the tea drink was three to five times lower than those of the overall content of this metal.

Potentiometric stripping analysis of methyl and ethyl parathion employing carbon nanoparticles and halloysite nanoclay modified carbon paste electrode

Carbon nanoparticles (CNPs) and halloysite nanoclay (HNC) modified carbon paste electrode (HNC–CNP–CPE) was developed for the determination of methyl parathion (MP) and ethyl parathion (EP). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and potentiometric stripping analysis (PSA). After optimization of analytical conditions employing this electrode at pH 5.0 in acetate buffer (0.1M), the peak currents were found to vary linearly with its concentration in the range of 1.55×10−9 to 3.67×10−6M and 1.21×10−9 to 4.92×10−6M for MP and EP, respectively. The detection limits (S/N=3) of 4.70×10−10M and 3.67×10−10M were obtained for MP and EP, respectively, using PSA. The prepared modified electrode showed several advantages such as simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of MP and EP in fruits, vegetables, water and soil samples.

Detection of double stranded DNA and its damage by liquiritigenin with copper (II) on multi-walled carbon nanotubes

The adsorption and electro-oxidation of double stranded (ds) DNA on multi-walled carbon nanotubes (MWNTs), which was directly grown on graphite electrode, was investigated through potentiometric stripping analysis (PSA), and the influence factors, such as accumulation time, immersion time and DNA concentration, were examined in detail. By using the MWNTs modified electrode, liquiritigenin (4′,7-dihydroxyflavone), which was synthesized in medium strong acid circumstance, was firstly found to cause dsDNA damage in the presence of Cu(II) by observing a new peak at 0.84V and an increase at 1.06V in the PSA spectrum when liquiritigenin was introduced into the dsDNA and Cu(II) solution. Liquiritigenin exhibited two conflicting effects, i.e., pro-oxidation and anti-oxidation at its different concentrations in the damage system. Biquinoline and catalase were found to inhibit the dsDNA damage, which showed that Cu(I) and H2O2 participated in the damage process. Piezoelectric quartz crystal impedance (PQCI) analysis was also used to further validate the DNA damage, and the frequency shift was found to be mainly due to the change on density–viscosity of the tested solution which was caused by the degradation of the DNA macromolecules. A possible mechanism of oxidative DNA damage induce by liquiritigenin in the presence of Cu(II) on multi-walled carbon nanotubes was proposed.

Trace lead monitoring in waters by potentiometric stripping analysis

A monitoring study on the presence of lead traces was realized on aqueous matrices by potentiometric stripping analysis. Assimilation of metal traces from environment, foods and drugs is an important process which contributes to metal bioaccumulation in the body. The method involves the direct acidification of the sample (20 mL) without further pre-treatments. The electrolysis time was fixed at 180 s, the potential at −900 mV, the electrolysis stripping time was maintained in 10 s. Lead solutions were used as internal standard to elaborate the calibration curve (R 2 >95%). The limit of quantitation resulted of 5 μg.L−1 . The method was validated on several water samples spiked with known amounts of lead. The method was applied to five Italian bottled water and eighteen water sources in the territory of Serra St. Bruno, Calabria, Italy, revealing the presence of traces of the metal in some of them.

Potentiometric Stripping Analysis of Zinc, Cadmium and Lead in Tobacco Leaves (Nicotiana Tabacum L.) and Soil Samples

Potentiometric Stripping Analysis of Zinc, Cadmium and Lead in Tobacco Leaves (Nicotiana Tabacum L.) and Soil Samples

Simultaneous Quantitation of Manganese (II) and Iron (III) In An Industrial Effluent Using Differential Pulse Polarography

In the present study, a successful attempt has been made to develop a simple method for the simultaneous determination of manganese (II) and iron (III) in an industrial effluent using differential pulse polarography (DPP) technique. Quantification of manganese (II) and iron (III) was done in Triethanolamine and KOH as a supporting electrolyte. The polarogram recorded for the industrial effluent in triethanolamine and KOH showed two peaks at -0.3V and ­0.82V vs. saturated calomel electrode which were confirmed to be of manganese (II) and iron (III) respectively by the method of standard addition. The linear working range for manganese (II) and iron (III) both was 1.408 µg/mL to 4.977 µg/mL. The proposed method was found to be simple, precise, and accurate and can be successfully applied for the analysis and simultaneous determination of manganese (II) and iron (III) in industrial effluents. Keywords: Differential pulse polarography, Industrial effluent, Iron (III), Manganese (II), Potassium hydroxide, Triethanolamine, I. Introduction Rapid industrialization and abnormal population growth has enhanced water pollution. Monitoring the metal ions and organic compounds in aquatic environment has been a subject of great concern over the last few decades and will continue to be so, as increasing number of metal ions in increasing amounts and a diverse array of organic compounds form a part of an industrial effluent. The heavy metals like Lead, Cadmium, Mercury, Arsenic, Iron, Nickel, Copper and others are used widely in industries. Thus, monitoring of these toxic substances is an integral part of environmental management. Some of these elements may be micronutrients for many living organisms and are required in small amounts for normal healthy growth, but any metal ion in large amount will always cause acute or chronic toxicity. Manganese is an essential trace mineral. The mineral is considered to be essential for the formation of healthy red blood cells, proper pituitary gland function, and the maintenance of good eyesight. Manganese is not only necessary for humans to survive, but it is also toxic when too high concentrations are present in a human body. Iron is a dietary requirement for most organisms. In small quantities, certain metals are nutritionally essential for a healthy life. These elements are also found in commercially available multivitamin products. Water soluble binary iron compounds such as FeSO4, FeCl2 may cause toxic effects with exceeding concentrations. The present paper deals with simultaneous quantitation of such electroactive species which are commonly associated with effluents from pharmaceutical industries. Potentiometric stripping analysis of simultaneous determination of metal ions has been reported

The Release of Zinc, Copper, Lead, and Cadmium from the Mineral Tissue of Teeth under the Influence of Soft Drinks and Sour-Tasting Food

This study was carried out with the aim of identifying the effects of consuming sour-tasting food and refreshing drinks on the bone tissue of teeth among teenagers. The cumulative effect of a year-long exposure of teeth to the erosive effects of a model system of acidic media (citric acid, lactic acid, acetic acid, apple vinegar, lemonade, the soft drink Sprite, mineral water) was studied. The effects were registered based on the amount of released biometal ions, of zinc and copper, and toxic lead, during a period of 24 hr at room temperature, using the potentiometric stripping analysis. In the given time span, amounts ranging from 75 to 750 ppm of zinc, from 0.1 to 1.0 ppm of copper, and up to 1.5 ppm of lead were released from the dental matrix, while the release of cadmium was below the level of detection. The changes to the mineral structure of the bone tissue were monitored by the Fourier’s transformation infrared spectroscopy and scanning electron microscopy technique. These studies have shown that under the influence of an acidic medium significant erosion to the tooth enamel ensues and that the eroded surfaces had a radius of 1–5 μm.

Potentiometric stripping analysis of antimony based on carbon paste electrode modified with hexathia crown ether and rice husk

An electrochemical method based on potentiometric stripping analysis (PSA) employing a hexathia 18C6 (HT18C6) and rice husk (RH) modified carbon paste electrode (HT18C6–RH-CPE) has been proposed for the subnanomolar determination of antimony. The characterization of the electrode surface has been carried out by means of scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry. By employing HT18C6–RH-CPE, a 12-fold enhancement in the PSA signal (d t/d E) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, d t/d E (s V −1) was proportional to the Sb(III) concentration in the range of 1.42 × 10 −8 to 6.89 × 10 −11 M ( r = 0.9944) with the detection limit (S/N = 3) of 2.11 × 10 −11 M. The practical analytical utilities of the modified electrode were demonstrated by the determination of antimony in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limit and excellent reproducibility. Moreover, the results obtained for antimony analysis in commercial and real samples using HT18C6–RH-CPE and those obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES) are in agreement at the 95% confidence level.

Determination of copper, lead, cadmium and zinc content in commercially valuable fish species from the Persian Gulf using derivative potentiometric stripping analysis

This study was performed to determine the concentrations of cadmium, lead, copper and zinc in the edible muscle of pelagic (Scomberomorus commerson, Chirocentrus dorab, Sphyraena jello, Rachycentron conadum, Thunus tonggol, and Tenualosa ilisha) and demersal (Nemipterus japonicas, Epinephelus coioides, Platycephalus indicus, Psettodes erumei, Pomadasys argenteus, and Acanthopagrus latus) fish species from the Persian Gulf during winter and summer. The samples were analyzed by the derivative potentiometric stripping technique; and the results were expressed as μg/g of wet weight. The obtained range of metals in fish species was 0.024–0.111μg/g for cadmium, 0.057–0.471μg/g for lead, 0.799–4.790μg/g for copper and 3.226–11.390μg/g for zinc. The study revealed that seasonal variation influenced the concentration of metals in the samples. The highest concentration of cadmium, lead, copper and zinc was found in Platycephalus indicus (0.147μg/g), Acanthopagrus latus (0.534μg/g), Psettodes erumei (5.294μg/g) and Psettodes erumei (13.528μg/g) in winter, respectively. Moreover, demersal fish species had higher cadmium, lead and zinc concentrations, but lower copper content than pelagic ones. Our study demonstrated that the estimated daily and weekly intakes of lead, copper and zinc, and estimated monthly intake of cadmium via consumption of fish flesh were below the PTDI, PTWI and PTMI values established by FAO/WHO.

Applications of nanoscale carbon-based materials in heavy metal sensing and detection

This article reviews applications of nanoscale carbon-based materials in heavy metal sensing and detection. These materials, including single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers among others, have unique and tunable properties enabling applications in various fields spanning from health, electronics and the environment sector. Specifically, we highlight the unique properties of these materials that enable their applications in the sorption and preconcentration of heavy metals ions prior to detection by spectroscopic, chromatographic and electrochemical techniques. We also discuss their distinct properties that enable them to be used as novel electrode materials in sensing and detection. The fabrication and modification of these electrodes is discussed in detail and their applications in various electrochemical techniques such as voltammetric stripping analysis, potentiometric stripping analysis, field effect transistor-based devices and electrical impedance are critically reviewed. Perspectives and futures trends in the use of these materials in heavy metal sensing and detection will also be highlighted.

Potentiometric stripping analysis of bismuth based on carbon paste electrode modified with cryptand [2.2.1] and multiwalled carbon nanotubes

An electrochemical method based on potentiometric stripping analysis (PSA) employing a cryptand [2.2.1] (CRY) and carbon nanotube (CNT) modified paste electrode (CRY–CNT-PE) has been proposed for the subnanomolar determination of bismuth. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). It was observed that by employing CRY–CNT-PE, a 9-fold enhancement in the PSA signal ( dt/ dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/ dE (s/V) was proportional to the Bi(III) concentration in the range of 5.55 × 10 −8 to 9.79 × 10 −11 M ( r = 0.9990) with the detection limit (S/N = 3) of 3.17 × 10 −11 M. The practical analytical utilities of the modified electrode were demonstrated by the determination of bismuth in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the results obtained for bismuth analysis in commercial and real samples using CRY–CNT-PE and those obtained by atomic absorption spectroscopy (AAS) are in agreement at the 95% confidence level.

Determination of Magnesium and Calcium in Biological Samples by Potentiometric Stripping Analysis

AbstractA new and simple method for determination of calcium and magnesium in human plasma and hair samples was investigated by using potentiometric stripping analysis. The replacement reactions between Ca2+ and Zn‐EGTA (Ethylene glycol‐bis‐(2‐aminoethyl)tetraacetic acid) complex and between Mg2+ and Zn‐EDTA (Ethylenediamine tetraacetic acid disodium salt) complex were utilized. The determinations were carried out in NH4Cl‐NH3 buffer solutions of pH 9.54 for calcium and of pH 10.18 for magnesium, respectively. Potential and time data were digitally converted into dtdE−1, and E was plotted vs. dtdE−1. Quantitative analysis was carried out by the method of standard additions. Linearity for determination of magnesium was found to be in the range of 6∼120 μg L−1 with a correlation coefficient of 0.997 (n = 6); and for determination of calcium in the range of 10∼250 μg L−1 with a correlation coefficient of 0.995 (n = 6). The detection limit of 4 μ gL−1 was found for both magnesium and calcium determination. This proposed method has been used for determining calcium and magnesium in biological samples with good recoveries and well accord with the results of Inductively Coupled Plasma‐Atomic Emission Spectrometry (ICP‐AES).

Selective and specific detection of sulfate-reducing bacteria using potentiometric stripping analysis

A fast, sensitive and reliable potentiometric stripping analysis (PSA) is described for the selective detection of the marine pathogenic sulfate-reducing bacterium (SRB), Desulforibrio caledoiensis. The chemical and electrochemical parameters that exert influence on the deposition and stripping of lead ion, such as deposition potential, deposition time and pH value were carefully studied. The concentration of SRB was determined in acetate buffer solution (pH 5.2) under the optimized condition (deposition potential of −1.3 V, deposition time of 250 s, ionic strength of 0.2 mol L −1 and oxidant mercury (II) concentration of 40 mg L −1). A linear relationship between the stripping response and the logarithm of the bacterial concentration was observed in the range of 2.3 × 10 to 2.3 × 10 7 cfu mL −1. In addition, the potentiometric stripping technique gave a distinct response to the SRB, but had no obvious response to Escherichia coli. The measurement system has a potential for further applications and provides a facile and sample method for detection of pathogenic bacteria.

Application of the Potentiometric Stripping Analysis with Constant Current for the Determination of Lithium Ions Using a Spinel-Type Manganese (IV) Oxide-Modified Carbon Paste Electrode

A potentiometric stripping method for the measurement of lithium ions at a carbon paste electrode modified with spinel-type manganese oxide is described. The procedure is based on the effective pre-concentration of lithium ions on an electrode surface containing spinel-type MnO2, with the reduction of Mn(IV) to Mn(III), and the consequent intercalation (insertion) of the lithium ions into the spinel structure. The best current constant stripping analysis (CCSA) response was reached for an electrode composition of 25% (m/m) spinel-type MnO2 in the paste, 0.1 mol L–1 TRIS buffer solution at pH 8.0, an accumulation potential of 0.3 V vs. the saturated calomel reference electrode (SCE), a preconcentration time of 90 s and the application of a small positive constant current (10 μA) during the stripping step. The obtained limit of detection was 2.0 x 10–7 mol L–1, and the relative standard deviation from five measurements of 2.5 × 10-6 mol L–1 lithium ions was 3.8%. Keywords: Lithium ions, Spinel-type manganese oxide, Potentiometric stripping analysis

Copper Release from Dental Prosthetic Crowns, Dental Materials, and Human Teeth into Acetic Acid

This article examines the dilution of the ion of copper from human teeth and dental prosthetic crowns in 4% CH3COOH during a period of 24 hr at room temperature. The content of the diluted copper in an acetate extract, as well as the overall content of this metal in the samples, was determined by means of a potentiometric stripping analysis. The comparative measurements were carried out using the furnace atomic absorption spectrophotometry technique, which is recommended by the International Standards (ISO 6872:2008; ISO 24234:2004) as a method for quality control of dental-prosthetic material (dental ceramic, metal restorative materials, dental amalgams) in the process of checking for heavy metals. During a 24-hr period in 4% CH3COOH at a temperature of 25°C, ∼72% of the overall copper was released from the tooth. The percentage of the released copper from baby teeth is higher, ranging from 88 to 92%, which is probably a consequence of the bone tissue being in development, its infirmity, and inadequate stability. On these conditions, ∼72% of the overall copper was released from the dental-ceramic prosthetic crowns.

Levels of Cd (II), Mn (II), Pb (II), Cu (II), and Zn (II) in Common Buzzard (Buteo buteo) from Sicily (Italy) by Derivative Stripping Potentiometry

The purpose of this study was to determine the concentrations of heavy metals (Cd, Pb, Cu, Mn, and Zn) in different organs (liver, kidney, muscle, lung, skin, and feathers) of buzzards (Buteo buteo), utilized as a “biological indicator” for environmental contamination, from different areas of Sicily and to investigate the relationships between birds sex, age, and weight and metal levels in these samples. All samples of common buzzards were collected at the “Recovery Center of Wild Fauna” of Palermo, through the Zooprophilactic Institute. Potentiometric stripping analysis (PSA) was used to determine the content of Cd(II), Cu(II), Mn(II), Pb(II), and Zn(II) in bird tissues. For toxic metals, the highest levels of Pb were in liver and those of Cd in lung; Zn levels were higher than Cu and Mn in all tissues analyzed. The concentrations in liver, lung, kidney, and muscle could be considered as an indicative of chronic exposure to metals while the presence of metals in skin could be consequential to storing and elimination processes. The found concentrations of metals in the studied matrices required a highly sensitive method for their determination and a simple sample preparation procedure, and the proposed method was well suited for this purpose.

Principles and Techniques of Electroanalytical Stripping Methods for Pharmaceutically Active Compounds in Dosage Forms and Biological Samples

A review of the applications, principles, advantages of stripping voltammetric techniques, namely anodic, cathodic, abrasive, adsorptive stripping voltammetry and potentiometric stripping analysis is presented. Stripping voltammetric methods in pharmaceutical analysis are discussed and the generally applicable procedure is given. The use and advantages and disadvantages of these techniques at different electrodes are discussed. The analytical applications of stripping techniques to pharmaceutically active compounds are also discussed. Various selected determination studies on drugs by stripping techniques from pharmaceutical dosage forms and biological samples are reviewed. Keywords: Adsorptive stripping, Anodic stripping, Biological samples, Cathodic stripping, Determination, Potentiometric stripping, Drugs

Determination of urine manganese with differential potentiometric stripping analysis

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Potentiometric Stripping Analysis at Antimony Film Electrodes

AbstractNew procedures of potentiometric stripping analysis can be based on the use of antimony film electrodes and antimony(III) salts. In this paper, antimony films are generated onto carbon paste electrodes in situ and after electrolytic preconcentration of the metals to be determined, the excess antimony(III) serves as a chemical oxidant. Moreover in acidic solutions containing halide ions, the oxidation ability of antimony(III) is adequately limited because of formation of its corresponding halide complexes. Compared with similar total substitution of traditionally used mercury(II) by bismuth(III), the use of antimony(III) offers higher sensitivity in detection of heavy metals, namely, cadmium and lead.