Potentiometric stripping analysis

Potentiometric stripping analysis (PSA), known also as stripping potentiome-try, differs from ASV in the method used for stripping the amalgamated metals (30). In this case, the potentiostatic control is disconnected following the preconcentration, and the concentrated metals are reoxidized by an oxidizing agent [e.g., 02, Hg(II)] that is present in the solution  

A stirred solution is used also during the stripping step to facilitate the transport of the oxidant. Alternately, the oxidation can be carried out by passing a constant anodic current through the electrode. During the oxidation step, the variation of the working electrode potential is recorded, and a stripping curve, 

About 20 amalgam-forming metals, including Pb, Sn, Cu, Zn, Cd, Bi, Sb,Tl, Ga, In, and Mn, are easily measurable by stripping strategies (ASV and PSA) based on cathodic deposition onto mercury electrodes. Additional metals, such as Se, Hg, Ag, Te, and As, are measurable at bare solid electrodes such as carbon or gold. 

After the total amount of the analyte 1 is oxidized, the potential changes become fast again as long as the oxidizing potential of the next analyte is achieved. Therefore, a transient slightly resembling a multiple redox titration curve is obtained. The transition times needed for the oxidation of the deposited metals are used for the evaluation. The peak shaped diJdE versus E plot makes the evaluation more convenient. 

By changing the deposition time, the oxidant concentration, or the electrode size, the method can be adjusted to the different analytical tasks. Most often, the trace levels of Cu, Pb, Bi, Sn, and Cd ion concentrations are measured with potentiometric stripping analysis. 

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METHOD DEVELOPMENT FOR THE POTENTIOMETRIC STRIPPING ANALYSIS OF SOLUBLE COPPER IN DENTAL MATERIALS... 

Describe clearly the principle and operation of potentiometric stripping analysis (PSA). How it is differed from anodic stripping voltammetry (ASV) What is the quantitative signal What is its advantage over ASV ... 

Potential of zero charge, 20, 23, 25, 66 Potential scanning detector, 92 Potential step, 7, 42, 60 Potential window, 107, 108 Potentiometry, 2, 140 Potentiometric stripping analysis, 79 Potentiostat, 104, 105 Preconcentrating surfaces, 121 Preconcentration step, 121 Pretreatment, 110, 116 Pulsed amperometric detection, 92 Pulse voltammetry, 67... 

Fig. 3.67. E-t curves of potentiometric stripping analysis (Psa) and its derivative (Dpsa) for 0.1 fiM Zn, Pb and Cd in 0.1 M NaCl (chemical stripping).

Potentiometric stripping analysis has been applied by Sheffrin and Williams [320] to the measurement of copper in seawater at environmental pH. The advantage of this technique is that it can be used to specifically measure the biologically active labile copper species in seawater samples at desired pH values. The method was applied to seawater samples that had passed a 0.45 pm Millipore filter. Samples were studied both at high and at low pH values. 

Table 5.4. Analysis of poor quality seawater by potentiometric stripping analysis and atomic absorption spectroscopy and good quality seawater by potentiometric stripping analysis... 

Drabek et al. [803] applied potentiometric stripping analysis to the determination of lead, cadmium, and zinc in seawater. The precision was evaluated by several duplicate determinations and was found to be in the range 5-16% relative, depending on the concentration level. The accuracy of the method was evaluated by comparison with other conventional methods, e.g., AAS and ASV, and good agreement between the methods was found. 

Eskilsson et al. [868] have described equipment for automated determination of traces of cobalt and nickel by potentiometric stripping analysis, which used a freshly prepared mercury film on a glassy carbon support as the working... 

Potentiometric stripping analysis (PSA) is another attractive version of stripping analysis [7]. The preconcentration step in PSA is the same as for ASV that is, the metal is electrolytically deposited (via reduction) onto the mercury electrode (usually a film). The stripping, however, is done by chemical oxidation, for example, with oxygen or mercuric ions present in the solution ... 

Figure 24.4 Potentiometric stripping analysis of a solution containing 1.5 x 10 6 M Zn2+, Cd2+, Pb2+, and Cu2+, using 3-min deposition and mercury as an oxidant.

Electrochemical measurements have been developed by using different electrochemical techniques (differential pulse voltammetry (DPV), cyclic voltametry (CV), potentiometric stripping analysis (PSA), square wave voltammetry (SWV), adsorptive stripping transfer voltammetry (ASTV), etc.). The abbreviations given in covalent attachment of DNA onto different transducers are water soluble carbodimide l-(3-dimethyaminopropyl)-3-ethyl-carbodimide (EDC), IV-hydroxysuccimide (NHS), mercaptohexanol (MCH), aminoethanethiol (AET), mercaptosilane (MSi), and N-cyclohexyl-lV -[2-(N-methylmorpholino)-ethyl]carbodimide-4-tolune sulfonate (CDS). 

Insulin Oxidation of tyrosine residues at pre-treated (+1.7V, 30s) microfabricated SPCEs Potentiometric stripping analysis (2 min accumulation at -0.2V) Stripping current of 3 pA 0-600 nM 20nM Wang et al. [76]... 

SPMBE = screen-printed microband electrode, ASV = anodic stripping voltammetry, HCMV = human cytomegalovirus, PGE = pencil-graphite electrode, DPV = differential pulse voltammetry, SPEs = screen-printed electrodes, PSA = potentiometric stripping analysis, M-GECE = magnetic graphite-epoxy composite electrode. 

Other techniques applied to speciation studies are potentiometric stripping analysis (PSA) (Oagner and Aren, 1982), pseudopolarography (Brown and Kowalski, 1979), electrophoresis (Rohl, 1982), several chromatographic techniques, XAD-1 and -2 (Mackey,... 

Equation (7.116) indicates that the charge-potential curves for reversible processes are only dependent on the square wave amplitude Sw and are independent of the frequency / = 1 jh and the staircase amplitude AEs. As a consequence, they are superimposable on those obtained at any differential electrochemical technique, such as DSCVC, provided that the differences between the successive potential pulses coincide (AE = 2 sw)- Moreover, when this difference is much less than RT/F (i.e., less than 25 mV at T = 198 K), the responses obtained in Cyclic Voltammetry (CV), Alternating Current Voltammetry, Potentiometric Stripping Analysis (PSA) and also in any Reciprocal Derivative Chronopotentiometry (RDCP) fulfill [5, 74, 75] ... 

Town, R.M. (1997) Potentiometric stripping analysis and anodic stripping voltammetry for measurement of Cu(II) and Pb(II) complexation by fulvic acid a comparative study. Electroanalysis, 9, 407-415. 

EDTA was determined in waste water by Fayyad et al, who used potentiometric stripping analysis after adding Bi(III) and K C O to the test solution. Uncomplexed Bi(III) was electrodeposited on a mercury film electrode (at -0.4 V vs. SCE) for 50 seconds. The working range was 4.5-95 ppb of EDTA [20]. 

Depending on the circumstances at hand, several different types of mean comparisons can be made. In this section we review the method for comparison of two means with independent samples. Other applications, such as a comparison of means with matched samples, can be found in statistical texts. Suppose, for example, we have two methods for the determination of lead (Pb) in orchard leaves. The first method is based on the electrochemical method of potentiometric stripping analysis [1], and the second is based on the method of atomic absorption spectroscopy [2], We perform replicate analyses of homogeneous aliquots prepared by dissolving the orchard leaves into one homogeneous solution and obtain the data listed in Table 3.1. 

Rozali bin Othman, M., Hill, J.O., and Magee, R.J., Determination of lead and cadmium in biological samples by potentiometric stripping analysis, Fresenius Zeitschrift fuer Analytische Chemie, 326, 350-353, 1987. 

Wang, J. Cai, X. Wang, J. Johnsson, C. Palecek, E. Trace measurements of RNA by potentiometric stripping analysis at carbon paste electrodes. Anal. Chem. 1995, 67, 4065-4075. 

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