Stripping voltammetry linear anodic

Peak currents in anodic stripping voltammetry are a linear function of concentration... 

Scarponi et al. [781] studied the influence of an unwashed membrane filter (Millpore type HA, 47 mm diameter) on the cadmium, lead, and copper concentrations of filtered seawater. Direct simultaneous determination of the metals was achieved at natural pH by linear-sweep anodic stripping voltammetry at a mercury film electrode. These workers recommended that at least 1 litre of seawater be passed through uncleaned filters before aliquots for analysis are taken the same filter can be reused several times, and only the first 50-100 ml of filtrate need be discarded. Samples could be stored in polyethylene containers at 4 °C for three months without contamination, but losses of lead and copper occurred after five months of storage. 

The principles of thin-layer anodic stripping voltammetry were discussed, and a model for the stripping stage was developed for anodization by a linear potential ramp [35]. The experimental test of the theories was carried out for cadmium and lead amalgams. 

A common approach used in a number of investigations is to modify the SPCE with a thin film of Hg. Recently, Palchetti et al. [152] have reported on the use of an SPCE modified with a thin film of Hg and cellulose (Methocel) for the determination of Pb2+, Cd2+ and Cu2+, using square-wave anodic stripping voltammetry. Detection limits of 0.3, 1 and 0.5 pgl-1 were obtained for Pb2+, Cd2+ and Cu2+, respectively deoxygenation of sample solution was found unnecessary. In all cases, linearity ranging from lpgl 1 to lmgl-1 and correlations of 0.9998 for Cd and Pb, and 0.9987 for Cu were obtained. 

Anodic stripping voltammetry (ASV) was applied to the determination of copper traces present as Cu(dik)2. The differential pulse technique was used to strip the amalgamated copper from a hanging mercury drop electrode. The experimental variables such as scan rate of electrode potential, deposition potential, deposition time and stirring speed of the solution could be optimized. The linear range of the calibration plot was 0.05-1 (xM and the LOD was 0.014 fiM Cu(II). A method was used for the determination of copper in breast milk and beer as typical examples of application, consisting of minerahzation of the sample, extraction of Cu(II) from the aqueous solution with a 1 M solution of acacH in chloroform and ASV end analysis . 

Part IV is devoted to electrochemical methods. After an introduction to electrochemistry in Chapter 18, Chapter 19 describes the many uses of electrode potentials. Oxidation/reduction titrations are the subject of Chapter 20, while Chapter 21 presents the use of potentiometric methods to obtain concentrations of molecular and ionic species. Chapter 22 considers the bulk electrolytic methods of electrogravimetry and coulometry, while Chapter 23 discusses voltammetric methods including linear sweep and cyclic voltammetry, anodic stripping voltammetry, and polarography. 

Preconcentration in a slightly different way is described by Eisner and Mark (40) who equilibrated small areas of cation exchange membranes with sample solutions and then used the membrane as a source of ions for deposition in an anodic stripping voltammetry system. The concentration of the ion in the membrane is linearly related to its concentration in the bulk sample solution. The pre-equilibrated membrane was also analyzed by neutron activation thus extending the range of ions for which the technique is useful. Data are quoted for Ag+, Cu2+, Zn2+, Co2+ and In3+, all of which show favourable distribution for the membrane phase. Equilibration times are inversely proportional to concentration ranging from several minutes at lO"1 M to one day or more at 10 6 M. The method affords a convenient separation from nonionic and anionic species which interfere with the measurement technique. 

Of these, anodic stripping voltammetry (43), both linear sweep and differential pulse, incorporates a pre-concentration feature and therefore... 

The fuming HNO3 digestion procedure was used in conjunction with differential pulse anodic stripping voltammetry to determine sensitivity, linearity of response, measurement precision, and lead background or blank levels. Recovery studies, as well as some interference studies, were also conducted. It should be emphasized that the data presented in this discussion were obtained in a particular laboratory situation. Practical detection limits were determined both by the laboratory environment and by the ability of the analyst to reduce both the variability and magni-... 

Studies made with this instrumentation on other voltammetrlc techniques such as anodic stripping voltammetry allow one to conclude that the optimization of initial d.c. linear sweep or stripping data leads to optimum performance In the semi-integral, semi-differential and derivative approaches and that, under Instrumental equivalent conditions where d.c. experiments have been optimized with respect to electronic noise and background correction, detection limits are not markedly different within the sub-set of related approaches. Obviously, the resolution and ease of use of a method providing a peak-type readout (semi-differential) are superior to those with sigmoidally shaped read- outs (semi-integral). 

In anodic stripping voltammetry of amalgams and metal deposits, there is no theoretical limit of detection of metal ions. If the accumulation potential is on the plateau of the pseudopolarogram and the solution is stirred, a steady state is established and the concentration of metal ions is linearly proportional to the duration of the accumulation ... 

See also Voltammetry Linear Sweep and Cyclic Anodic Stripping Cathodic Stripping Inorganic Compounds Organic Compounds. 

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