Determination of nanomolar concentrations of lead and cadmium by anodic-stripping voltammetry at the silver electrode (original) (raw)
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In situ electrodeposition for the determination of lead and cadmium in sea water
Analytica Chimica Acta, 1981
Electrodeposition techniques for the direct determination of lead and cadmium in sea water at the natural pH and in the presence of dissolved oxygen are examined. Anodic stripping vohammetry, at either the hanging mercury drop electrode or glassy carbon thin film electrode, is suitable for the determination of labile lead and cadmium. The presence of dissolved oxygen increases the height of the lead wave with a shift to more negative potentials. A more versatile technique is in situ deposition of labile metals on a mercurycoated graphite tube electrode. The mercury film, deposited in the laboratory, is stable on the dried tubes which are used later for field ektrodepositick The deposited metals are determined by electrothermal atomic absorption spectrometry.
Analytica Chimica Acta, 1982
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.
Analytical and Bioanalytical Chemistry, 2008
The main thrust of this work involves method validation, quality control and sample uncertainty estimations related to the determination of cadmium and lead in marine water by anodic stripping voltammetry. We have followed a step-by-step protocol to evaluate and harmonize the internal quality aspects of this method. Such protocol involves a statement of the method's scope (analytes, matrices, concentration level) and requisites (external and/ or internal); selection of the method's (fit-for-purpose) features; prevalidation and validation of the intermediate accuracy (under intermediate precision conditions) and its assessment (by Monte Carlo simulation); validation of other required features of the method (if applicable); and a validity statement in terms of a "fit-for-purpose" decision, harmonized validation-control-uncertainty statistics (the "u-approach") and short-term routine work (with the aim of proposing virtually "ready-to-use" methods).
Analytica Chimica Acta, 1995
Highly sensitive procedures are presented for the determination of sub-nanomolar concentrations of total dissolved lead and labile lead in sea water by adsorptive cathodic stripping voltammetry with ligand competition using xylenol orange (X0). Optimal analytical conditions were found to be an X0 concentration of 1 X 1O-5 M, a pH of 5, and an adsorption potential at-1.2 V vs. Ag/AgCl with stripping from-0.2 V. The limit of detection for a 180 s stirred adsorption time is 6 ng I-', making the method amenable to the determination of lead in open ocean waters.
Determination of lead and cadmium in seawater using a vibrating silver amalgam microwire electrode
Analytica Chimica Acta, 2013
h i g h l i g h t s A vibrating silver amalgam microwire (SAM) is used as electrode in voltammetry. The SAM has sufficient sensitivity to determine Pb in uncontaminated seawater. The SAM is vibrated during the deposition step to increase the sensitivity. The new electrode and method are more sensitive than pre-existing electrodes. The limit of detection is 4 pM Pb and 100 pM Cd in acidified seawater.
Analytica Chimica Acta, 1979
Sea-water samples collected by a variety of clean sampling techniques yielded consistent results for copper, cadmium, zinc, and nickel, which implies that representative, uncontaminated samples were obtained. A dithiocarbamate extraction method coupled with atomic absorption spectrometry and electro,thermal atomization is described which is essentially 100% quantitative for each of the four metals studied, has lower blanks and detection limits, and yields better precision than previously published techniques. A more precise and accurate determination of these metals in sea water at their natural ng 1-l concentration levels is therefore possible. Samples analyzed by this procedure and by concentration on Chelex-100 showed similar results for cadmium and zinc. Both copper and nickel appeared to be inefficiently removed from sea water by Chelex-100. Comparison of the organic extraction results with other pertinent investigations showed excellent agreement.
Analytica Chimica Acta, 1981
Water samples from the Arctic Sea were analyzed by the potentiometric stripping technique_ Lcad(II) and cadmium(I1) were determined after pre-electrolysis for 32 min at -1.1 V vs. Ag/AgCl, the detection limits being 0.06 and 0.04 nM, respectively. Zinc(I1) -determin ed after the addition of gallium(III) by pre-electrolysis for 16 min at -1.4 V vs. Ag/AgCI, the detection limit being 0.25 nM. Problems in the determination of copper(II) at the very low concentrations found in oceanic waters are outlined. The average zinc(n), cadmium(II) and lead(II) concentrations in eight different samples were 2.5, 0.16 and 0.10 nM as determined by potentiometric stripping analysis and 1.9, 0.16 and 0.09 nM as determined by solvent extraction/atomic absorption spectrometry. The advantages of this computerized technique for the analysis of sea water are discussed.
Concentrations of cadmium and lead heavy metals in Dardanelles seawater
Environmental Monitoring and Assessment, 2007
Cadmium and lead were determined simultaneously in seawater by differential pulse stripping voltammetry (DPSV) preceded by adsoptive collection of complexes with 8-hydroxyquinoline (oxine) on to a hanging mercury drop electrode (HMDE). In preliminary experiments the optimal analytical condition for oxine concentration was found to be 2.10−5 M, at pH 7.7, the accumulation potential was −1.1 V, and the initial scannig potential was −0.8 V. The peak potentials were found −0.652 V for Cd and −0.463 V for Pb At the 60 s accumalation time. The limit of detection (LOD) and limit of quantitatification (LOQ) were found to be by voltammetry as 0.588 and 1.959 μg l−1 (RSD, 5.50%) for Cd and 0.931 and 3.104 μg l−1 (RSD, 4.10%) for Pb at 60 s stirred accumulation time respectively. In these conditions the most of the seawater samples are amenable for direct voltammetric determination of cadmium and lead using a HMDE. An adsorptive stripping mechanism of the electrode reaction was proposed. For the comparison, seawater samples were also analysed by ICP-atomic emission spectrometry method (ICP-AES). The applied voltammetric technique was validated and good recoveries were obtained.