Simultaneous determination of several trace metals in seawater using cathodic stripping voltammetry with mixed ligands

Colombo, Carlo; Berg, Constant M.G. van den

doi:10.1016/s0003-2670(96)00401-1

Cited by 70 publications

(46 citation statements)

References 15 publications

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“…However, such requirements are greatly met with electrochemical methods. Recently, cathodic stripping voltammetry in the presence of mixed ligands [13], differential pulse anodic stripping voltammetry [14,15] and anodic stripping voltammetry [16] with ultrasensitive detection limits are reported for the simultaneous determination of zinc and cadmium and some other metals. On the other hand, the major interference…”

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confidence: 99%

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

2010

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A novel, simple and sensitive adsorptive stripping voltammetry method was developed for simultaneous determination of Cd and Zn using N-Nitrozo-N-phenylhydroxylamine (Cupferron) as a selective complexing agent. Cadmium and zinc metals gave peaks that were distinctly separated by 450-1200 mV, allowing their determination over a wide range of concentrations. The influence of pH and the nature of supporting electrolytes, concentration of ligand, preconcentration time and applied potential were investigated. The detection limits were 0.058 ng/mL for Zn and 0.092 ng/mL for Cd, and the RSD at a concentration level of 50 ppb, were 1.8-2.1 % for both zinc and cadmium, respectively. The method was applied to the determination of cadmium and zinc in blood, drug, food and water samples with the satisfactory results. Zinc is a metal of prime environmental concern. Cadmium is among the toxic metal of significance for environmental surveillance, food control and occupational medicine, toxicology and hygiene. To study the environmental problems and environmental control, simple and sufficiently sensitive methods for the determination of these and other metals are necessary. A few methods allow the simultaneous determination of metals in real samples, mainly voltammetric methods [1-6] and chromatographic method [7]. For the simultaneous determination of trace elements in real samples, (foods samples, drug samples, water, etc.), voltammetric techniques are very suitable owing to their high sensitivity and relative simplicity and because only very simple pretreatment of the sample is required [8]. Stripping electrochemical techniques such as anodic stripping voltammetry (ASV) and potentiometric stripping analysis (PSA) can be used to simultaneously measure Cd and Zn in solution. These techniques combine low maintenance costs with high sensitivity and selectivity that allows the determination of low levels of metals without prior treatment of the sample. Linear-scan ASV has been applied to the direct determination of toxic metals in untreated solutions of sugar and PSA has been used for metal determinations in digested solutions of oils, tea and sugar [5].The applications of adsorptive stripping voltammetry (AdSV) in the determination of trace and ultratrace metals have been reviewed elsewhere [9]. One of the future trends in AdSV is multi-element analysis and two or three metals can be determined in a single scan owing to the metal specificity of the ligands. The advantages and disadvantages of advanced electroanalytical techniques versus AAS, ICP-AES and ICP-MS in environmental analysis have been reviewed elsewhere [10]. Recently several analytical techniques such as flame atomic absorption spectroscopy [11], inductively coupled plasma mass spectrometry [12] with ultra sensitive detection limits are reported for quantification of zinc and cadmium. However maintains and operational costs of these techniques are expensive and require adequate expertise. Therefore, the analysis is often limited to laboratory level. Since rel...

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confidence: 99%

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

2010

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“…Nevertheless, neither the ligand physicochemical state nor the adsorbed complex stoichiometry can be inferred from this analysis. Our experimental responses also point that ferron molecules offer a wider pH range for working with adsorptive stripping voltammetry than other commonly used quinoline derivatives in the trace analysis of cadmium [12,13,17,19].…”

Section: Resultsmentioning

confidence: 63%

“…The experimental responses of Cd(II)-Fer complexes provided a wider pH range for working with adsorptive stripping voltammetry than with other commonly used quinoline derivatives in the trace analysis of cadmium [12,13,17,19]. In addition, the theory predicts a maximum response of DI p f À1 for this kind of quasi-reversible systems, giving a powerful tool in order to choose the best operative conditions for analytical applications [8,11,30].…”

Section: Discussionmentioning

confidence: 99%

Adsorptive Square‐Wave Voltammetry for the Analysis and Speciation of Complexes of Cd(II)‐Ferron

Garay

Solı́s

2004

Electroanalysis

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The theory of adsorptive stripping square-wave voltammetry (SWV) for relatively low ligand concentrations is employed to determine the reduction mechanism of Cd(II)-ferron complexes accumulated on a static mercury drop electrode at different pH values. The electrochemical behavior of ferron molecules indicated that the adsorptive concentration of Cd(II) is possible in solutions with 3.5 < pH < 11, providing a wide pH range where the interference of other ligands present in real samples would be not so critical. Cyclic voltammetry experiments were also performed for the purpose of comparison. Fitting between experimental and theoretical square-wave voltammograms shows that the prevailing species at the reaction layer coincide with the equilibrium bulk distribution. The simulation procedure indicated that the electrochemical rate constants of Cd(II)-ferron complexes varied from (6 AE 1) s À1 to (0.17 AE 0.01) s À1for solutions analyzed at pH 3.9 and 10.8, respectively. Changes at the surface concentrations are discussed considering the ligand to complex ratios at the electrode surface and at the solution bulk. From this analysis it is possible to infer that the oxidized metal species are produced in the electrolytic solution instead of on the electrode surface.

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“…Since all of these buffers are zwitterionic acids with pK a values between 6.8 (PIPES) and 8.1 (HEPPS), they are suitable for the experiments in the pH range close to that in natural waters. However, it has recently been observed that the HEPES enhances electrochemical signal of Co(II) and Ni(II)-cyclohexane-1,2-dione dioxime (nioxime) complexes, Fe(III)-salicylaldoxime (SA) complex, as well as Cu(II)-8-hydroxyquinoline (oxine) complex between two and four times [15][16][17]. The effect of the buffer was initially detected when the reduction current of the metal complex increased and its peak potential shifted.…”

Section: Introductionmentioning

confidence: 99%

Influence of the HEPES Buffer on Electrochemical Reaction of the Copper(II)-Salicylaldoxime Complex

1998

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The effect of the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) on the redox process of copper(II)-salicylaldoxime complex [Cu(II)-SA] was studied. The measurements were performed on a hanging mercury drop electrode (HMDE) using various electrochemical techniques. The presence of the HEPES buffer (pH 8.0) doubled the reduction current of the Cu(II)-SA complex, whereas the reduction potential shifted to more positive values (about 50 mV). The results obtained indicate that the presence of the HEPES buffer facilitates the electron transfer between the mercury electrode and the adsorbed Cu(II)-SA complex during the reduction process. The experiments carried out using chronocoulometry with a double step potential revealed that the surface coverage of the Cu(II)-SA complex remained unchanged (in the range between 9 and 10.5 × 10 ¹11 mol cm ¹2 ), regardless of the presence of the HEPES buffer. Square-wave voltammetric measurements also indicate that the redox process of the Cu(II)-SA complex is electrochemically reversible with the reactant adsorption, in spite of the presence of the HEPES buffer.

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Simultaneous determination of several trace metals in seawater using cathodic stripping voltammetry with mixed ligands

Cited by 70 publications

References 15 publications

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

Adsorptive Square‐Wave Voltammetry for the Analysis and Speciation of Complexes of Cd(II)‐Ferron

Influence of the HEPES Buffer on Electrochemical Reaction of the Copper(II)-Salicylaldoxime Complex

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