Preparation of electrochemically treated nanoporous pencil-graphite electrodes for the simultaneous determination of Pb and Cd in water samples (original) (raw)
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International journal of analytical chemistry, 2018
The present work reports the development and application of bismuth-film electrode (BiFE), obtained by in situ method on the pencil-lead graphite surface, for simultaneous Cd(II) and Pb(II) determination at trace levels, as alternative to replace the mercury-film electrodes. Experimental factors, deposition time ( ), deposition potential ( ), and Bi(III) concentration ( ), were investigated by applying a 2 factorial design using 0.10 mol/L acetate buffer solution (pH 4.5) as supporting electrolyte. The analysis conditions of the differential pulse technique were = 250 s, = -1.40 V, and = 250 mg L. The validation of the method employing BiFE was accomplished by determination of merit figures. The detection limits were of 11.0 g L for Cd(II) and 11.5 g L for Pb(II), confirming that proposed method is attractive and suitable for heavy metals determination. Additionally, the BiFE developed was successfully applied for the Cd(II) and Pb(II) determination in wastewater sample of battery i...
Journal of Electrochemical Science and Engineering, 2019
Glassy carbon electrode (GCE) modified by 2-mercaptobenzothiazole (MBT), mesoporous silica (Meso) and bismuth was developed to determine Cd(II) and Pb(II) simultaneously by square wave anodic stripping voltammetry (SWASV). In-situ preparation was found to work best in optimum conditions of acetate buffer pH 6, accumulation potential of-1.1 V, deposition time of 300 s and scan rate of 200 mV/s. SW peaks revealed the linear range of 5-50 µg/L Cd(II) and 5-50 µg/L Pb(II). LOD and LOQ for Cd(II) and Pb(II) were determined as 0.56, 0.80, 1.87 and 2.66 µg/L, respectively. The interaction of metals with bismuth and MBT, as well as higher surface area due to mesoporous silica, support beneficial performance of the modified electrode. Insignificant interferences from other regularly present metal ions were found. With SRM1640 standard, the SWASV results are found comparable to those obtained by inductive coupled plasma optical emission spectrometry (ICP-OES). The method was used to analyze the metals in tap water by standard addition method with the satisfactory recovery of 100.7 % for Cd(II) and 100.8 % for Pb(II).
Electroanalysis, 2011
The determination of Pb and Cd with a Nafion-modified glassy carbon electrode and Cu-DPABA complex (Cu-DPABA-NA/GCE; DPABA is methyl 3,5-bis{bis-[(pyridin-2-yl)methyl]amino}methyl-benzoate) as an alternative electrode for anodic stripping voltammetry was described. Pb and Cd were accumulated in acetate buffer pH 4 at a potential of À1.4 V (vs. Ag/AgCl electrode) for 120 s followed by a DPASV scan from À1.2 to À0.2 V. Under optimum conditions the calibration curves were linear in the range of 4.8 10 À9-5.0 10 À5 and 5.0 10 À9-5 10 À5 mol L À1 for Pb and Cd, respectively. Detection limits were 1.8 10 À9 and 1.2 10 À9 mol L À1 for Pb and Cd, respectively. Different parameters and conditions, such as membrane ingredients, accumulation time, potential and pH value were optimized. A study of interfering substances was also performed. A significant increase in current was achieved at the modified electrode in comparison with the bare glassy carbon electrode. The validation of the proposed method was made by Pb and Cd determination in the certified reference material Groundwater CRM 610 (BCR, Community Bureau of Reference, Brussels, Belgium). The electrode was successfully applied for determination of Pb and Cd in river water with a high content of organic contaminants without any pretreatment.
Microchimica Acta, 2014
We report on a glassy carbon electrode modified with bismuth nanoparticles (NanoBiE) for the simultaneous determination Pb 2+ and Cd 2+ by anodic stripping voltammetry. Operational parameters such as bismuth nanoparticles labelling amount, deposition potential, deposition time and stripping parameters were optimized with respect to the determination of Pb 2+ and Cd 2+ in 0.1 M acetate buffer solution (pH 4.5). The NanoBiE gives well-defined, reproducible and sharp stripping peaks. The peak current response increases linearly with the metal concentration in a range of 5.0-60.0 μg L −1 , with a detection limit of 0.8 and 0.4 μg L −1 for Pb 2+ and Cd 2+ , respectively. The morphology and composition of the modified electrode before and after voltammetric measurements were analysed by scanning electron microscopy and energy dispersive X-ray analysis. The NanoBiE was successfully applied to analysis of Pb 2+ and Cd 2+ in real water samples and the method was validated by ICP-MS technique, suggesting that the electrode can be considered as an interesting alternative to the bismuth film electrode for possible use in electrochemical studies and electroanalysis.
International Journal of Environmental Analytical Chemistry, 2019
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.
Journal of Electroanalytical Chemistry, 2010
This work describes a novel type of renovated silver ring electrode (RSRE), as mercury-free sensor, for anodic stripping voltammetry (ASV). The great advantages of the RSRE are simplicity, periodic renovation of the surface and the possibility of repetitive measurements on the surface completely free from reaction products, adsorbed surface-active species, etc. The sensor was tested for the detection of nanomolar concentrations of Pb 2+ and Cd 2+ by ASV in water samples without removal of oxygen and surfactants. Detection limits of 0.5 nM for Pb 2+ and 2 nM for Cd 2+ have been achieved following 60 s electrodeposition. The validation of the proposed RSRE was made by Pb 2+ and Cd 2+ determination using the certified reference materials (Surface Waters). The RSRE was successfully applied to Pb 2+ and Cd 2+ analysis in tap water and to river water with a high content of organic contaminants.
Scienceasia, 2010
A simple and rapid method to determine traces of lead in the Hatyai city tap water by square wave anodic stripping voltammetry with boron-doped diamond (BDD) electrode has been studied. The parameters in the preconcentration steps studied included electrolyte influences, pH, concentrations, and volumes. Effective preconcentration of trace lead was achieved at pH 1.26. The appropriate electrolyte was found to be 0.2 M potassium nitrate (KNO3) in 0.05 M nitric acid (HNO3) to make all lead ionic. By scanning potential in the negative direction, the stripping peak was obtained at 0.460 V. Instrumental parameters including deposition potential, deposition time, scan rate, modulation amplitude, and equilibration time were optimized. The detection limit was found to be 0.3 µg/l. The accuracy was verified by analysing the standard reference material. Several interfering ions were studied and it was found that the method was not significantly affected by these coexisting ions and can be appl...
Electroanalysis, 2014
A method using commercially available sputtered bismuth screen-printed electrodes (Bi sp SPE), as substitute to mercury electrodes, for the determination of trace Pb(II) and Cd(II) ions in drinking well water samples collected in a contaminated area in The Republic of El Salvador by means of differential pulse anodic stripping voltammetry (DPASV) has been proposed. The comparable detection and quantification limits obtained for both Bi sp SPE and hanging mercury drop electrode (HMDE), together with the similar results with a high reproducibility obtained in these water samples analyses recommend the applicability of Bi sp SPE for the determination of low level of metal concentrations in natural samples.
Sensors, 2019
In this work, we explore the protection with Nafion of commercial sputtered-bismuth screen-printed electrodes (Bi SP SPEs), to improve its ability for on-site determination of Cd(II) and Pb(II) ions in ambient water samples. The modified screen-printed platform was coupled with a miniaturized cell, in combination with a battery-operated stirring system and a portable potentiostat operated by a laptop for decentralized electrochemical measurements using Square-Wave Anodic Stripping Voltammetry (SWASV). We also describe a detailed electrode surface characterization by microscopy and surface analysis techniques, before and after the modification with Nafion, to get insight about modification effect on signal size and stability. Optimization of the chemical composition of the medium including the optimization of pH, and instrumental parameters, resulted in a method with detection limits in the low ng/mL range (3.62 and 3.83 ng·mL −1 for Cd and Pb respectively). Our results show an improvement of the sensitivity and stability for Nafion-protected Bi SP SPEs in pH = 4.4 medium, and similar or lower detection limits than comparable methods on commercial Bi SP SPEs. The values obtained for Pb(II) and Cd(II) in natural water samples agreed well with those obtained by the much more costly Inductively Coupled Plasma Mass Spectrometry, ICP-MS, technique as a reference method (recoveries from 75% to 111%).
Electrochimica Acta, 2013
A new chemically modified electrode was constructed for rapid, simple, accurate, selective and highly sensitive simultaneous determination of lead and cadmium using square wave anodic stripping voltammetry (SWASV). The electrode was prepared by incorporation of new synthesized Schiff base and multi-walled carbon nanotubes (MWCNT) in carbon paste electrode. The limit of detection was found to be 0.25 ng mL −1 and 0.74 ng mL −1 for Pb 2+ and Cd 2+ , respectively. The stability constants of the complexes of the ligand with several metal cations in ethanol medium were determined. The effects of different cations and anions on the simultaneous determination of metal ions were studied and it was found that the electrode is highly selective. The proposed chemically modified electrode was used for the determination of lead and cadmium in several foodstuffs and water samples.