Anodic stripping voltammetric determination of antimony in gunshot residue

Anodic stripping voltammetry (a.s.v.) ata mercury film on a glassy carbon working electrode was utilized to determine the amount of antimony from hand swabs. The procedure described is useful for determining 10–120 ng of antimony found in the residue ou the hands of an individual suspected of discharging or handling a firearm. The voltammogram provides an elemental pattern recognizable as gunshot residue containing small amounts of antimony and much larger amounts of copper and lead. The amount of antimony in a variety of gunshot-residue samples was determined by both anodic stripping voltammetry and graphite-furnace atomic absorptiou spectrometry for comparison purposes. Anodic stripping voltammetry is excellent for observation of the multielement pattern which proves to be very useful for gunshot-residue samples.     

Anodic stripping voltammetry with the florence mercury film electrode. determination of copper,lead and cadmium in sea water

The use of the rotating glassy carbon electrode mercury plated in situ for anodic stripping voltammetry has been investigated. The choice of electrode material is discussed. The effect of instrumental parameters on the stripping response for copper, lead and cadmium in sea water is studied, the results being in accordance with the theory of thin film electrodes. The variation in the observed sensitivity for the three metals in sea water is discussed in terms of complex-forming ligands. Lastly the performance of the film electrode is compared to that of the hanging mercury drop electrode.     

The determination of lead,copper and cadmium by anodic stripping voltammetry at a mercury thin-film electrode

The determination of lead, copper and cadmium by anodic stripping voltammetry at a wax-impregnated graphite electrode, pre-plated with mercury, has been investigated. Electrode preparation and cell design are discussed, and the effects of mercury loading and sample pH on electrode sensitivity are described. Detection limits and precision on aqueous samples are reported. Calibration graphs are linear for lead and cadmium, but non-linear for low concentrations of copper. The depression of peak current and shift of peak potential for copper in chloride media are described and an explanation is proposed. Precision and recovery of metal additions are reported for digested samples of whole blood.     

Pulsed anodic stripping voltammetry of zinc,cadmium and lead with a mercury-coated wax-impregnated graphite electrode

The use of a thin mercury-film wax-impregnated graphite electrode for the simultaneous determination of cadmium, lead and zinc in an acetate buffer by differential pulse anodic stripping voltammetry is described. Optimal instrumental parameters for maximum resolution and sensitivity for simultaneous analysis of these three elements in natural waters are discussed. The interference of copper with the determination of zinc is investigated in detail. An optimal mercury film thickness for this electrode is suggested.     

Optimization and comparison of four mercury working electrodes in speciation studies by differential-pulse anodic stripping voltammetry

Four types of working electrodes are compared with respect to sensitivity, resolution, peak width and suitability for copper speciation studies by differential-pulse anodic stripping voltammetry. The hanging mercury drop electrode, two rotating mercury film electrodes with in-situ and pre-formed films and a stationary mercury film electrode with a vibrationally induced jet-stream are examined. The last electrode appears to be the most useful system with the highest sensitivity. Conditions for mercury film formation must be optimized for each individual electrochemical system in order to avoid erroneous conclusions from standard addition procedures and apparent complexation capacity measurements.     

The determination of trace amounts of zinc, cadmium, lead and copper in airborne particulate matter by anodic stripping voltammetry

The application of anodic stripping voltammetry, with a hanging mercury drop electrode, to the determination of zinc, cadmium, lead and copper in airborne particulate matter collected by filtration is discussed. This procedure allows for the destruction of the filter material followed by the complete dissolution (including silicates) of the collected particulate matter. A low-temperature ashing process is described and the recovery of cadmium in this procedure is studied. Analytical data obtained by anodic stripping and atomic absorption for zinc, cadmium, lead and copper are compared.     

Silver based mercury film electrode: Part IV. Comparison of theoretical and experimental voltammetric results obtained for cadmium

Using the silver based mercury film electrode (SBMFE) and cyclic and stripping voltammetric techniques the behaviour of cadmium has been compared with the behaviour of lead as well as with the predictions of the theory of de Vries and van Dalen. At the SBMFE with film thickness between 0.1 and 2 μm lead behaves with good agreement with theoretical predictions and only at thicknesses higher than 2 μm some deviations occur due to collecting of the excess mercury at the bottom of the wire electrode. On the other hand even at thin film electrodes the behaviour of cadmium deviates significantly from the predictions of the theory. The height of the anodic peak decreases and its width increases; also the displacement of the potentials of both cathodic and anodic peaks is smaller than the values predicted theoretically. The deviations are caused neither by the formation of intermetallic compounds in the bulk of mercury phase nor by the formation of heterogenous cadmium amalgam; they reflect the interaction between cadmium dissolved in mercury and the solid silver amalgam which is the substrate of the mercury film. Owing to the effect discussed the stripping determination of cadmium at SBMFE is characterized by a lower sensitivity and reproducibility.     

Effect of mercury(II) on metal complex labilities determined by direct-current anodic stripping voltammetry on a thin mercury film electrode

The labilities of copper, lead and cadmium complexes with fulvic acid, nitrilotriacetic acid and an iron-humic acid colloid were studied on a preplated thin mercury film electrode and with in-situ plating of mercury on a glassy carbon electrode. In the presence of mercury(II) the apparent labilities based on direct-current anodic stripping voltammetric peak-area measurements increased for each of the cadmium and lead species and for the copper iron-humic acid colloid species. In contrast, for the copper complexes with nitrilotriacetic acid and fulvic acid the lability was not measurably altered by mercury(II); it is inferred that they do not undergo rapid metal exchange with mercury(II).     

Anodic stripping voltammetry at a mercury film electrode: baseline concentrations of cadmium,lead, and copper in selected natural waters

A simple, rapid, and inexpensive anodic stripping voltammetric method with a mercury thin film electrode is reported for the establishment of baseline concentrations of cadmium, lead, and copper in natural waters. The procedure for routine surface preparation of wax-impregnated graphite mercury film electrodes requires about 30 min. Concentrations in the 0.006–6 μg l^-1 range are determined by linear d.c. voltage sweeps; the total time for a plating and stripping cycle is 6 min or less. The need for pressure-digesting samples for copper determinations is demonstrated. The a.s.v. results correlate well with corresponding analyses performed by graphite-furnace atomic absorption spectrometry.     

Application of sampled-d.c. anodic stripping voltammetry to metal/fulvic acid equilibria

The use of anodic stripping voltammetry (ASV) to determine the labile metal fraction in metal/ fulvic acid equilibrium systems is discussed. A method is described for distinguishing between the contributions of processes in the reduction and oxidation steps to the observed anodic (stripping) current. This method, which facilitates separate examination of the two processes, is based on timed addition of fulvic acids during the deposition step, on pH control, and on measurement of sampled-d.c. ASV peak areas (Faradaic charge) for metal/fulvic acid solutions. Results are presented for copper(Il) and lead(Il) complexes with six colloid-free soil-derived fulvic acids. In contrast to differential-pulse ASV, the stripping current measured by sampled-d.c. ASV showed no measurable contribution from ligand adsorption on the mercury drop. For heterogeneous ligand systems, such as fulvic acid, use of stripping peak heights over-estimates the fraction of non-labile metal complex because peak broadening results from the range of complexes formed in the anodic step.     

Determination of traces of metals by anodic stripping voltammetry at a rotating glassy carbon ring—disc electrode: Part 1. Method and instrumentation with evaluation of some parameters

The equipment and procedure are described for the determination without preconcentration of several heavy metals based on d.c. anodic stripping voltammetry at a rotating ring—disc glassy carbon electrode with in situ mercury plating. During stripping of the metals deposited on the disc, the current from the reduction of the ions collected at the ring is measured. Some parameters (scan rate, thickness of the mercury film, electrode rotation and deposition time) influencing the ring collection peak current are examined experimentally. The results are compared with the theoretical considerations given by de Vries and van Dalen for anodic stripping voltammetry on a stationary mercury film electrode and by Bakanov et al. for a rotating mercury film electrode.     

Nature of a Positive Anodic Peak in the Stripping Voltammogram of Binary Platinum–Metal Systems

The effect of platinum on the electrodeposition of cadmium, lead, copper, and mercury at the surface of a solid electrode was studied by stripping voltammetry. It was shown that an additional current peak in the anodic voltammogram corresponded to the metal ionization to support electrolytic platinum.     

Effect of surface-active compounds on voltammetric stripping analysis at the mercury film electrode

The effects of various organic compounds on the differential-pulse anodic-stripping voltammetric response at the in-situ plated mercury film electrode are explored. These effects vary from metal to metal and from one organic compound to another. The most pronounced effects are observed in measurements of copper. The main effect of the organic compound is to depress the peak current rather than change the peak shape or potential. The differences between the organic interferences observed at the mercury film electrode and those reported at the hanging mercury drop electrode are explained by the different morphology and geometry of the two electrodes. The implications of these interferences for the reliability and feasibility of stripping measurements in natural waters are discussed. Gelatin, camphor, humic acid, starch, agar, sodium dodecyl sulphate and albumin were used as representative organic compounds, and cadmium, lead, and copper as test metal ions.     

The determination of zinc,cadmium, lead and copper in a single sea-water sample by differential pulse anodic stripping voltammetry

A comparative study is described of the anodic stripping voltammetry of sea water at its natural pH and at acetate-buffered pH, with a mercury film electrode. The reproducibility of the oxidation current peaks for copper and lead is improved and the electrode memory effect decreases, when the sample is acetate-buffered (pH 5.8). Determinations of zinc at the natural pH of sea water are inaccurate, because of the formation of Zn—Cu and Zn—Ni intermetallic compounds in the mercury film. The formation of such compounds can be prevented by the addition of gallium ions to acetate-buffered samples. A procedure for the determination of Cu, Pb, Cd and Zn in sea water is described.     

Anodic stripping voltammetry and chronopotentiometry of copper at a rotating carbosital disk electrode

The use of a new carbon material — carbosital — for electrodes is reviewed. The behaviour of copper deposited on the carbosital electrode surface in anodic stripping voltammetry and chronopotentiometry is discussed. In anodic stripping voltammetry with a rotating carbosital disk electrode, the peak current and the number of coulombs involved in stripping copper are directly proportional to the square root of the electrode rotation rate during preelectroiysis; the peak current is directly proportional to the potential scan rate during stripping. For anodic stripping voltammetry and anodic stripping chronopotentiometry, linear calibration graphs are obtained in the range 1 X 10^-3–1 x 10^-6 M copper(II). The method is applicable to analysis of high-purity cadmium for copper.     

Determination of arsenic and antimony in electrolytic copper by anodic stripping voltammetry at a gold film electrode

A simple procedure is described for the determination of arsenic and antimony in electrolytic copper. The copper is digested with nitric acid and copper is separated from arsenic and antimony by passing an ammoniacal solution of the sample through a column of Chelex-100 resin. After digestion with sulphuric acid and reduction to arsenic(III) and antimony(III) with sodium sulphite in 7 M sulphuric acid at 80°C, both arsenic and antimony are deposited at-0.30V and their total is determined by anodic stripping; antimony is then selectively deposited at -0.05 V for anodic stripping. The lower limits of determination are 56 ng As and 28 ng Sb per gram of copper; relative standard deviations (n = 5) are in the ranges 6.1–15.0% for 5.5—0.5 ppm arsenic in copper and 4.1–6.8% for 2.6—0.6 ppm antimony.     

The determination of copper,lead and cadmium in sea water by differential pulse anodic stripping voltammetry

The effect of various instrumental parameters is investigated and optimized conditions established. The results are in accordance with the theory of differential pulse anodic stripping voltammetry. Both a hanging mercury drop electrode, and a rotating glassy carbon electrode mercury plated in situ were used. The best detection limit is obtained with the mercury film electrode, but the hanging mercury drop electrode is more reproducible. The differential pulse stripping technique is compared to linear sweep stripping, and increased sensitivity and better peak separation is demonstrated for the former technique, particularly when a hanging mercury drop electrode is used. However, the differential pulse technique will also improve the detection limit for a mercury film electrode, if the electrode has a non-ideal response with a corresponding high background current.     

Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.     

Determination of Copper(II) Through Anodic Stripping Voltammetry in Tartrate Buffer Using an Antimony Film Screen-printed Carbon Electrode

The voltammetric performance of an in situ plated antimony film screen-printed carbon electrode in hydrochloric acid, acetate buffer, and tartrate buffer was evaluated for the detection of copper(II) with differential pulse anodic stripping voltammetry. The tartrate buffer was superior, providing high sensitivity and good separation of copper and antimony stripping peaks. The analytical conditions for the determination of copper(II) were optimized. The detection limit was estimated to be 0.14?µg?L^?1 copper(II) and the relative standard deviation for 2.5?µg?L^?1 copper(II) was 3%. The applicability of the method was illustrated by the analysis of soil conditioner samples.     

预镀铋膜阳极溶出伏安法测定废水中微量铅和镉

本文采用预镀铋膜法修饰玻碳电极,并用该电极对废水中微量铅和镉同时进行了阳极溶出伏安法测定,研究了预镀铋膜测定铅和镉的条件。实验结果表明:铅和镉在铋膜电极上可得到灵敏的电位溶出峰,峰高和溶出电位与汞膜电极法相近,使用预镀铋膜电极可避免使用汞电极带来的环境污染。