Determination of Cu, Pb, Cd, and Zn in river sediment extracts by sequential injection anodic stripping voltammetry with thin mercury film electrode

Determination of Zn2+ and Cd2+ by glassy carbon electrode modified with Perilla frutescens activated carbon

A Perilla frutescens (L.) Britton activated carbon that had high specific surface area (HSAPFAC) was modified on the surface of the glassy carbon electrode (GCE) for preparing a HSAPFAC/GCE, and on this basis, a differential pulse voltammetry (DPV) method for the simultaneous determination of zinc and cadmium ions (Zn2+ and Cd2+) was developed by using HSAPFAC/GCE. The determination conditions such as the film thickness, deposition potential, deposition time, and electrolyte acidity were investigated. The amperometric determination was carried out in a NaAc–HAc buffer solution (0.1 mol L−1, pH 5.5) after enriching for 550 s at –1.3 V. The oxidation peaks appear at –1.160 V and –0.845 V for Zn2+ and Cd2+, respectively. The oxidation peak currents of Zn2+ and Cd2+ are proportional to their concentrations in the ranges of 0.5 ∼ 20 μg L−1 and 0.25 ∼ 10 μg L−1, with the detection limits of 0.15 μg L−1 and 0.01 μg L−1 (signal/noise (S/N) = 3). The proposed method was applied to the determination of Zn2+ and Cd2+ in tap water samples. The recoveries were 101.6%∼103.0% and 84.0%∼88.8%, respectively.

“One-drop-of-blood” electroanalysis of lead levels in blood using a foam-like mesoporous polymer of melamine–formaldehyde and disposable screen-printed electrodes

A foam-like mesoporous melamine–formaldehyde polymer was synthesized and deposited on disposable screen-printed electrodes for the electroanalysis of Pb²⁺ ions in blood.

Development of a sequential injection anodic stripping voltammetry (SI-ASV) method for determination of Cd(II), Pb(II) and Cu(II) in wastewater samples from coatings industry

This paper describes the development and validation of a sequential injection (SI) anodic stripping voltammetry (ASV) method using the hanging mercury drop electrode for accumulation of the heavy metal cations Cu(II), Pb(II) and Cd(II). The method was applied to wastewater samples after proper acid digestion in open vessels to eliminate matrix effects. For a deposition time of 90 s at the flow rate of 10 microl s(-1), the detection limits of the method were 0.06, 0.09 and 0.16 micromol L(-1) for Cd, Pb and Cu, respectively. Under these conditions the linear dynamic range was between 0.20 and 9.0 micromol L(-1) and the sampling frequency was 30 analyses per hour. The relative standard deviation of the method was 3%(n=7) at the concentration level of 2.0 micromol L(-1). The accuracy of the method was evaluated by spiking the samples with known amounts of the metal cations, and by comparison with an independent analytical technique, the inductively coupled plasma atomic emission spectroscopy (ICP-AES). Average recoveries were around of 84%, and the results showed no evidence of systematic errors in comparison to the ICP-AES.

Polymer-coated bismuth film electrodes for the determination of trace metals by sequential-injection analysis/anodic stripping voltammetry

In this work, the utility of polymer-coated bismuth film electrodes (BiFEs) was assessed for the simultaneous on-line determination of Cd(II), Pb(II) and Zn(II) by square-wave anodic stripping voltammetry (SWASV) in the sequential-injection analysis (SIA) mode. The polymeric Nafion coating was initially plated on a glassy carbon electrode forming part of the flow-through electrochemical cell. The subsequent steps of the bismuth layer generation, analyte preconcentration, voltammetric measurement and electrode cleaning were conducted on-line. For a sample volume of 1.2 mL, the limits of detection (at S/N=3) were 2 microg L(-1) for Cd(II) and Pb(II) and 6 microg L(-1) for Zn(II), the coefficients of variation at 20 microg L(-1) were 5.1% for Cd(II), 5.9% for Pb(II) and 6.2% for Zn(II) and the measurement frequency was between 10 and 20 h(-1) (depending on the sample volume aspirated). It is demonstrated that the polymer-coated BiFEs, combined with SIA, can provide an environmentally friendly, sensitive and robust tool to perform rapid and cost-efficient on-line monitoring of trace metals by ASV, even in the presence of surface-active compounds.

Dental Amalgam, an Alternative Electrode Material for Voltammetric Analyses of Pollutants

Liquid mercury and liquid mercury amalgams are superior electrode materials in voltammetry for analytical purposes. This is mainly due to the high overvoltage to hydrogen, which enables the detection of heavy metals with high negative half-wave potentials. Because of the toxicity of mercury and liquid mercury compounds, their use is increasingly restricted, and cannot be included in voltammetric devices for field and on-line applications. Authors have studied properties of dental amalgam as an electrode material in voltammetry. The results show that dental amalgam acts similarly to a silver electrode. Also, it has a high hydrogen overvoltage, allowing it to be used, e.g., for detection of zinc. In addition, due to special properties of dental amalgam compared with mercury itself, it is not toxic. New in this paper is the determination of nickel and cobalt on the dental amalgam electrode using adsorptive cathodic stripping voltammetry (AdCSV). Also, some new data on detection of zinc, cadmium, lead and thallium are presented. The results show that this electrode can be used over a long period of time without any maintenance, which is important for on-line analyses of pollutants in soil and groundwater.