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

Abstract

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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Electrochemical Reduction of Vanadium(V)‐Cupferron Complex, VO(cupf)2OH

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Sensitive adsorptive stripping voltammetric method for direct determination of trace concentration of lead in the presence of cupferron in natural water samples

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