An electrochemical sensor for stripping analysis of Pb(II) based on multiwalled carbon nanotube functionalized with 5-Br-PADAP

The present study serves to focus attention on the modification of multiwalled carbon nanotube with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) and its application for the development of a new, simple, and selective modified electrode in order to determine Pb(II) in standard alloys and water samples. The electrochemical method was based on open circuit accumulation of lead ions onto a 5-Br-PADAP-modified multiwalled carbon nanotube electrode and then their anodic stripping voltammetric determination. The linear range for Pb(II) ions was from 0.9 to 114.6 μg L⁻¹. The detection limit and relative standard deviation were found to be 0.1 μg L⁻¹ and 1.6%, respectively. This method demonstrates the powerful application of carbon nanotubes in the field of mercury-free electrodes in voltammetric stripping analysis.

     

Square wave anodic stripping voltammetric determination of lead(II) using a glassy carbon electrode modified with a lead ionophore and multiwalled carbon nanotubes

We report on a glassy carbon electrode (GCE) modified with a lead ionophore and multiwalled carbon nanotubes. It can be applied to square wave anodic stripping voltammetric determination of Pb(II) ion after preconcentration of Pb(II) at ?1.0?V (vs. SCE) for 300?s in pH?4.5 acetate buffer containing 400?μg?L^?1 of Bi(III). The ionophore-MWCNTs film on the GCE possesses strong and highly selective affinity for Pb(II) as confirmed by quartz crystal microbalance experiments. Under the optimum conditions, a linear response was observed for Pb(II) ion in the range from 0.3 to 50?μg?L^?1. The limit of detection (at S/N?=?3) is 0.1?μg?L^?1. The method was applied to the determination of Pb(II) in water samples with acceptable recovery.

Stripping voltammetric determination of Cd(II) based on multiwalled carbon nanotube functionalized with 1-(2-pyridylazo)-2-naphthol

The present work has focused on the modification of multiwalled carbon nanotube with a ligand,l-（2-pyridylazo）-2-naphthol, and its potential application for the development of a new,simple and selective modified glassy carbon electrode for stripping voltammetric determination of Cd（Ⅱ）.The analytical curve for Cd（Ⅱ） ions covered the linear range varying from 0.8 up to 220.4μgL^-1.The limit of detection was found to be 0.1μgL^-1,while the relative standard deviation（RSD） at 50.0μgL^-1 was 1.8%（n=5）.This modified electrode was successfully applied for determination of Cd（Ⅱ） in some water samples.     

Ex Situ Prepared Antimony Film Electrode for Electrochemical Stripping Measurement of Heavy Metal Ions

The antimony film electrode (SbFE) was prepared ex situ for anodic and adsorptive stripping voltammetric measurement of selected heavy metal ions. The electrode revealed good linearity for Cd(II) and Pb(II) in a nondeaerated solution of 0.01 M HCl in the examined concentration range from 25 to 80 μg L^?1 with limits of detection of 1.1 μg L^?1 for Cd(II) and 0.3 μg L^?1 for Pb(II) and an excellent reproducibility. The preplated SbFE was also preliminary tested for measuring low levels of Ni(II) using adsorptive stripping voltammetry exhibiting good linearity and sensitivity in combination with only a 30 s deposition step.     

A glassy carbon electrode modified with antimony and poly(p-aminobenzene sulfonic acid) for sensing lead(II) by square wave anodic stripping voltammetry

We have developed a sensor for the square wave anodic stripping voltammetric determination of Pb(II). A glassy carbon electrode was modified with a thin film of an antimony/poly(p-aminobenzene sulfonic acid) composite in air-saturated aqueous solution of pH 2.0. Compared to a conventional antimony film electrode, the new one yields a larger stripping signal for Pb(II). The conditions of polymerization, the concentration of Sb(III), the pH value of the sample solution, the deposition potential and time, frequency, potential amplitude, and step increment potential were optimized. Under the optimum conditions, a linear response was observed for Pb(II) in the range of 0.5 to 150.0 μg?L^?1. The detection limit for Pb(II) is 0.1 μg?L^?1.

ABTS‐Multiwalled Carbon Nanotubes Nanocomposite/Bi Film Electrode for Sensitive Determination of Cd and Pb by Differential Pulse Stripping Voltammetry

A 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate) diammonium salt (ABTS)‐multiwalled carbon nanotubes (MWCNTs) nanocomposite/Bi film modified glassy carbon (GC) electrode was constructed for the differential pulse stripping voltammetric determination of trace Pb²⁺ and Cd²⁺. This electrode was more sensitive than ABTS‐free Bi/GC and Bi/MWCNTs/GC electrodes. Linear responses were obtained in the range from 0.5 to 35 μg L^?1 for Cd²⁺ and 0.2 to 50 μg L^?1 Pb(II), with detection limits of 0.2 μg L^?1 for Cd²⁺ and 0.1 μg L^?1 for Pb²⁺, respectively. This sensor was applied to the simultaneous detection of Cd²⁺ and Pb²⁺ in water samples with satisfactory recovery.     

Determination of lead(II) in aqueous solution using carbon nanotubes paste electrodes modified with Amberlite IR-120

A new composite electrode is described for anodic stripping voltammetry determination of Pb(II) at trace level in aqueous solution. The electrode is based on the use of multiwalled carbon nanotubes and Amberlite IR-120. The anodic stripping voltammograms depend, to a large extent, on the composition of the modified electrode and the preconcentration conditions. Under optimum conditions, the anodic peak current at around ?0.57 V is linearly related to the concentration of Pb(II) in the range from 9.6?×?10^?8 to 1.7?×?10^?6 mol L^?1 (R?=?0.998). The detection limit is 2.1?×?10^?8 mol L^?1, and the relative standard deviation (RSD) at 0.24?×?10^?6 mol L^?1 is 1.7% (n?=?6). The modified electrode was applied to the determination of Pb(II) using the standard addition method; the results showed average relative recoveries of 95% for the samples analysed.

Determination of Copper(II) Through Anodic Stripping Voltammetry in Tartrate Buffer Using an Antimony Film Screen-printed Carbon Electrode

The voltammetric performance of an in situ plated antimony film screen-printed carbon electrode in hydrochloric acid, acetate buffer, and tartrate buffer was evaluated for the detection of copper(II) with differential pulse anodic stripping voltammetry. The tartrate buffer was superior, providing high sensitivity and good separation of copper and antimony stripping peaks. The analytical conditions for the determination of copper(II) were optimized. The detection limit was estimated to be 0.14?µg?L^?1 copper(II) and the relative standard deviation for 2.5?µg?L^?1 copper(II) was 3%. The applicability of the method was illustrated by the analysis of soil conditioner samples.     

Voltammetric analysis of Pb(II) in natural waters using a carbon paste electrode modified with 5-mercapto-1-methyltetrazol grafted on hexagonal mesoporous silica

A hexagonal mesoporous silica (HMS) functionalized with a 5-mercapto-1-methyltetrazole derivative was employed to prepare a chemically modified carbon paste electrode for Pb(II) detection in aqueous solution by square wave adsorptive stripping voltammetry. The optimal operating conditions were 5 min preconcentration time at pH 6.5, and 120 s electrolysis time in 0.2 mol L^?1 HCl. Under these conditions, the voltammetric signal increased linearly with the preconcentration time in the range 1 to 10 min and with the Pb(II) concentration in the range 1 to 100?µg L^?1. The electrode was reproducible and sensitive. Simultaneous determination of Pb, Cd and Cu was also carried out with the electrode. The accuracy of the method was validated by analysing Pb(II) in tap water and groundwater samples.     

Water hyacinth modified carbon paste electrode for simultaneous electrochemical stripping analysis of Cd (II) and Pb (II)

In this study, we demonstrated a highly sensitive electrochemical sensor for the simultaneous detection of Pb (II) and Cd (II) in aqueous solution using carbon paste electrode modified with Eichhornia crassipes powder by square wave anodic stripping voltammetry. The effect of modifier composition, pH, preconcentration time, reduction potential and time, and type of supporting electrolyte on the determination of metal ions were investigated. Pre-concentration on the modified surface was performed at open circuit. The modified electrode exhibited well-defined and separate stripping peaks for Pb (II) and Cd (II). Under optimum experimental conditions, a linear range for both metal ions was from 10 to 5000 μg L^?1 with the detection limits of 4.9 μg L^?1, 2.1 μg L^?1 for Cd(II) and Pb (II), respectively. The modified electrode was found to be sensitive and selective when applied to determine trace amounts of Cd (II) and Pb (II) in natural water samples.     

Carbon Paste Electrode Plated with Lead Film. Voltammetric Characteristics and Application in Adsorptive Stripping Voltammetry

A lead film plated in situ at a carbon paste support was tested as a novel, potential electrode for adsorptive stripping voltammetric determination of cobalt traces in an ammonia buffer solution. To show the practical applicability of the new electrode, a catalytic adsorptive Co system in a supporting electrolyte containing 0.1 M ammonia buffer, 5×10^?4 M nioxime and 0.25 M nitrite was selected and investigated as a model solution. Pb and Co ions were simultaneously accumulated in situ on the electrode surface: Pb ions electrochemically at ?1.3 V) and then at ?0.75 V, at which potential the Co(II)‐nioximate complex was also pre‐concentrated via adsorption. Instrumental parameters, such as the time of nucleation and formation of Pb film deposits, the time of accumulation of the Co‐nioxime complex at the PbF/CPE, and the procedures of electrode regeneration, were optimized to obtain good reproducibility and sensitivity of the Co response. The optimized procedure yields favorable and highly stable stripping responses with good precision (RSD=3% for a 5×10^?8 M Co) and good linearity (up to 5×10^?7 M, coefficient of determination, R=0.996). The detection limit was 4×10^?10 M Co (0.023 μg L^?1) for an accumulation time of 120 s. The method enables the determination of Co in the presence of high excesses of Ni or Zn. The voltammetric data were correlated with the structural characterization by scanning electron microscopy (SEM) and X‐ray fluorescence spectroscopy (XRF).     

Bismuth Film Microelectrode Modified with Overoxidized Poly‐1‐Naphtylamine Protective Membrane for Enhanced Stripping Voltammetric Detection

The application of protective overoxidized poly‐1‐naphtylamine membrane (ONAP) is demonstrated in combination with bismuth film microelectrode (ONAP‐BiFME) for anodic stripping voltammetric measurement of trace heavy metals in the presence of some selected surfactants. The ONAP membrane was electrochemically deposited on the surface of bare single carbon fiber microelectrode followed by the in situ or ex situ preparation of the bismuth film. The key operational parameters influencing the stripping performance of the ONAP‐BiFME were optimized and its electroanalytical performance was examined in the model solution containing Cd(II) and Pb(II) as test metal ions. The ONAP‐BiFME exhibited significantly enhanced stripping voltammetric response (approximately 70% for Cd(II) and 45% for Pb(II)) in comparison with unmodified BiFME in the absence of surfactants. In the presence of high concentrations, e.g., 20 mg L^?1, of anionic or cationic surfactants, the stripping signal for, e.g., Cd(II) decreased for less than 6% at the ONAP‐BiFME, whereas at the unmodified BiFME the signal attenuated considerably (approximately 38%). Moreover, in the presence of 10 mg L^?1 of nonionic surfactant Triton X‐100, the stripping signals at the bare BiFME were almost completely suppressed, whereas at the ONAP‐BiFME exhibited linear concentration behavior in the examined concentration range from 10 to 120 μg L^?1, with the calculated limit of detection of 5.0 μg L^?1 and 3.4 μg L^?1 for Cd(II) and Pb(II), respectively in connection with 60 s accumulation time. The attractive behavior of ONAP‐modified BiFME expands the applicability of bismuth‐based electrodes for measurement of trace heavy metals in real environments, where the presence of more complex matrix can be expected.     

Anodic Stripping Voltammetry Determination of Pb(II) and Cd(II) at a Bismuth/Poly(aniline) Film Electrode

Abstract

A novel voltammetric method—anodic—using a bismuth/poly(aniline) film electrode has been developed for simultaneous measurement of Pb(II) and Cd(II) at low µg L^?1 concentration levels by stripping voltammetry. The results confirmed that the bismuth/poly(aniline) film electrode offered high‐quality stripping performance compared with the bismuth film electrode. Well‐defined sharp stripping peaks were observed for Pb(II) and Cd(II), along with an extremely low baseline. The detection limits of Pb(II) and Cd(II) are 1.03 µg L^?1 and 1.48 µg L^?1, respectively. The bismuth/poly (aniline) electrode has been applied to the determination of Pb(II) in tap water samples with satisfactory results.     

Properties of Poly(sodium 4‐styrenesulfonate)‐Ionic Liquid Composite Film and Its Application in the Determination of Trace Metals Combined with Bismuth Film Electrode

A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1‐butyl‐3‐methyl‐imidazolium hexafluorophosphate (BMIMPF₆) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4‐styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)₆^4?/Fe(CN)₆^3? can be effectively improved at the PSS‐BMIMPF₆ modified GC. The bismuth modified PSS‐BMIMPF₆ composite film electrodes (GC/PSS‐BMIMPF₆/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS‐BMIMPF₆/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50 μg L^?1. And the detection limits were 0.07 μg L^?1 for Cd(II) and 0.09 μg L^?1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120 s, respectively. Finally, the GC/PSS‐BMIMPF₆/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy.     

Simultaneous Determination of Trace Zinc(II) and Cadmium(II) by Differential Pulse Anodic Stripping Voltammetry Using a MWCNTs–NaDBS Modified Stannum Film Electrode

A multiwalled carbon nanotubes–sodium dodecyl benzene sulfonate (MWCNTs–NaDBS) modified stannum film electrode was employed for the determination of cadmium(II) and zinc(II). The Sn/MWCNTs‐NaDBS film electrode was prepared by applying MWCNTs–NaDBS suspension to the surface of the GCE, while the Sn film was plated in situ simultaneously with the target metal ions. Under optimal conditions, linear calibration curves were obtained in a range of 5.0 ?100.0 μg L^?1 with detection limits of 0.9 μg L^?1 for zinc(II) and 0.8 μg L^?1 for cadmium(II), respectively. This film electrode was successfully applied to the determination of Zn(II) and Cd(II) in tap water sample.     

Synthesis and application of a natural-based nanocomposite with carbon nanotubes for sensitive voltammetric determination of lead (II) ions

ABSTRACT

A modified carbon paste electrode has been developed for the determination of Pb(ΙΙ) ions based on Fe₃O₄/eggshell magnetic nanocomposite. The structure and morphology of Fe₃O₄/eggshell were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared nanocomposite was also characterized by Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The electrochemical procedure was based on the accumulation and determination of Pb(ΙΙ) ions at the surface of the modified carbon paste electrode with Fe₃O₄/eggshell nanocomposites and carbon nanotubes by differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters involved in the preconcentration of Pb(ΙΙ) ions and voltammetric stripping step were studied. Under the optimum conditions, the voltammetric peak current of Pb(ΙΙ) occurs at a potential about ?0.5 V. Also, the voltammetric peak current increased linearly with Pb(ΙΙ) concentration in the range of 0.5–200 ng mL^?1 and a detection limit of 0.15 ng mL^?1 was obtained for Pb(ΙΙ). The selectivity of the proposed electrode for Pb(ΙΙ) ions in the presence of some cations was also examined. The practical application of the proposed modified electrode was evaluated by the determination of Pb(ΙΙ) ions in human hair and water samples. The results were satisfactory for the spiked samples.     

Glassy carbon electrode modified with organic�Cinorganic pillared montmorillonites for voltammetric detection of mercury

A glassy carbon electrode modified with organic?Cinorganic pillared montmorillonite was used for voltammetric detection of mercury(II) in water. High sensitivity is obtained due to the use of the montmorillonites which displays outstanding capability in terms of adsorbing mercury ion due to its high specific surface and the presence of multiple binding sites. The experimental parameters and the effect of a chelating agent were optimized to further enhance sensitivity and selectivity. Linear calibration curves were obtained over the Hg(II) concentration range from 10 to 800???g?L^?1 for 5?min accumulation, with a detection limit of 1???g?L^?1. Simultaneous determination of Hg(II) and Cu(II) was also studied, and no interference was observed.

Highly Sensitive and Selective Adsorptive Stripping Voltammetric Method Employing a Lead Film Screen‐printed Electrode for Determination of Cobalt as its Nioximate Complex

A carbon screen‐printed electrode modified in‐situ with lead film (PbF‐SPCE) was applied for the adsorptive stripping voltammetric determination of Co(II) in the form of a complex with 1,2‐cyclohexanedione dioxime. Lead film was electrochemically deposited in situ on SPCE from a 0.2 M ammonia buffer solution (pH 8.7) containing 5 ? 10^?5 M Pb(NO₃)₂ and 5 ? 10^?5 M nioxime. Due to the very low LOD (0.003 µgL^?1, i.e., 0.05 nmol L^?1 Co(II); t_acc=120s), the developed procedure could be rated among the most sensitive methods employing SPEs. The Ni(II) signal was significantly lower than the Co(II) one and the separation of Ni(II) and Co(II) peaks was even better at the PbF‐SPCE than at the hanging mercury drop electrode.     

Solid phase extraction based on modified multi-walled carbon nanotubes packed column for enrichment of copper and lead on-line incorporated with flame atomic absorption spectrometry

A simple and rapid solid phase extraction?Cflow injection procedure is developed for on-line trace determination of Cu(II) and Pb(II) by flame atomic absorption spectrometry (FAAS). Multi-walled carbon nanotubes modified with a new Schiff??s base, 2,2??-(1E, 1E??)-(4-Methyl-1, 2-phenylene) bis (azen-1-yl-1-ylidine) bis (Methane-1-yl-1-ylidene) diphenol was used as a novel adsorbent material. Quantitative simultaneous extraction was obtained at pH 7.0. The retained metal ions were then eluted efficiently with 1.0?M HNO₃ into the nebulizer of FAAS for on-line determination. Different variables affecting the preconcentration efficiency, including pH, eluent concentration, sample and eluent flow rates and sample loading time, were optimized. Using 3?min preconcentration of sample solution at flow rate of 5?mL?min^?1 provided the enrichment factors of 20 and 21.5 for Cu(II) and Pb(II), respectively, at a sampling frequency of 17?h^?1. The detection limits (3??) were found to be 0.80 and 1.80???g?L^?1 for Cu(II) and Pb(II), respectively; and the relative standard deviations at 0.05???g?mL^?1 of these metal ions were 1.7 and 1.8% (n?=?8), respectively. The accuracy was assessed by analysis of a certified reference material NKK-916 and the obtained results are in good agreement with certified amounts of Cu(II) and Pb(II). The proposed method was successfully applied to the determination of target analytes in different real samples.     

Enhanced sensing of anthraquinone dyes using multiwalled carbon nanotubes modified electrode

The voltammetric behaviour of two anthraquinone dyes such as Alizarin Red S (ARS) and Reactive blue 4 (RB4) was investigated at plain glassy carbon electrode (GCE), multiwalled carbon nano tube modified GCE (MWCNT/GCE) and zeolite modified GCE (ZE/GCE) using cyclic voltammetry. Effects of pH, scan rate and concentration were studied. The surface morphology of the modified electrode in the absence and presence of dye molecules was characterized by scanning electron microscopy (SEM). A systematic study on the variation of experimental parameters with differential pulse stripping voltammetry (DPSV) was carried out and the optimized experimental conditions were arrived. MWCNT/GCE performed well among the three electrode systems and the limit of detection (LOD) was 0.036?µg?mL^?1 for ARS and 0.05?µg?mL^?1 for RB4 on this modified system. Suitability of the differential pulse stripping voltammetric method for the trace determination of textile dyes in effluents was also realized.