DPASV

During production and characterization of various internal animal tissue reference materials for a number of metals, a comparative study was performed for Pb in six bovine teeth and two bovine bone materials using calibration with a solid RM and two versions of wet chemical analysis with GF-AAS and electrochemical (DPASV) detection. There was good agreement in the range of approx. 1.3-3 tng/kg dry weight for all techniques used (Liicker et al. 1992). 

DPASV Differential pulse anodic stripping voltammetry... 

The primary methods of analyzing for lead in environmental samples are AAS, GFAAS, ASV, ICP/AES, and XRFS (Lima et al. 1995). Less commonly employed techniques include ICP/MS, gas chromato-graphy/photoionization detector (GC/PID), IDMS, DPASV, electron probe X-ray microanalysis (EPXMA), and laser microprobe mass analysis (LAMMA). The use of ICP/MS will become more routine in the future because of the sensitivity and specificity of the technique. ICP/MS is generally 3 orders of magnitude more sensitive than ICP/AES (Al-Rashdan et al. 1991). Chromatography (GC,... 

Agricultural crops Dry ashing of sample with H2S04 and HN03 dilution with water DPASV 0.4 ng/g 85-106 Satzger et al. 1082... 

Figure 5.22. Voltammogram of the simultaneous determination of Cu, Pb, Cd, and Zn with DPASV at the HMDE, and subsequent determination of Selv by DPCSV in the same run in rain water at an adjusted pH of 2. Preconcentration time for DPASV 3 min at -1.2 V, for DPCSV 5 min at -0.2 V. 1 Original analyte. 2 After first standard addition. Total analysis time with two standards. Source Author s own files...

The electrochemical behaviour of trace concentrations of triphenylstannyl acetate, using a mercury film-glassy carbon electrode, was investigated by various measuring methods cyclic voltametry, differential pulse voltametry and controlled-potential electrolysis. Determination by DPASV (differential pulse ASV) of water and fish samples has LOD 2.5 nM98. 

Fig. 7.4. DPASV curves obtained with a graphite-epoxy composite electrode for increasing concentration of Cd, Pb, and Cu along with the corresponding calibration curves (inset). The cell composition was 25 mL 0.1 N HC1 the reference electrode Ag/AgCl counter electrode Pt accumulation potential —1.4V racc 60s step potential 0.0024V modulation time 0.05s interval time 0.2 s. Adapted from Ref. [35].

The GECE sensors were used for lead determination in real water samples suspected to be contaminated with lead obtained from water suppliers. The same samples were previously measured by three other methods a potentiometric FIA system with a lead ion-selective-electrode as detector (Pb-ISE) graphite furnace atomic absorption spectrophotometry (AAS) inductively coupled plasma spectroscopy (ICP). The results obtained for lead determination are presented in Table 7.1. The accumulation times are given for each measured sample in the case of DPASV. Calibration plots were used to determine the lead concentration. GEC electrode results were compared with each of the above methods by using paired -Test. The results obtained show that the differences between the results of GECE compared to other methods were not significant. The improvement of the reproducibility of the methods is one of the most important issues in the future research of these materials. 

CCcu and K determination by DPASV analysis. To illustrate the possibilities of speciation studies, an example of the application to natural waters will be presented in this section, with special reference to the determination of the complexation capacity for copper of marine waters. 

The techniques used were based on solvent extraction (e.g. with pentane), complexation (e.g. with diethyldithiocarbamate, EDTA), derivatisation (e.g. hydride generation, propylation or ethylation), and capillary GC separation followed by a range of detection techniques (e.g. QFAAS, ICPMS, MIP-AES, MS) DPASV has also been successfully used. In the frame of this project, two new techniques were also developed and successfully applied, namely supercritical fluid extraction followed by CGC/MS and isotope dilution ICPMS after ethylation and CGC separation. A full description of the techniques is given elsewhere (Quevauviller, 1998b). 

River water, snow UV lamp 150 W, pH 1 Bi, Sb DPASV-HMDE 14... 

The coupling of diazotized /i-aminoacetophenone (DPAAP) with imidazole forms the basis of the differential pulse adsorption stripping voltammetry (DPASV) method for detection of histidine and its metabolites. The absorption of azo-histidine was found to obey Frumkin absorption isotherm <1999TAL319>. 

ASV and DPASV are still useful speciation methods because of their sensitivity and their ability to distinguish labile metal species from strong (non-labile) organic complexes. Furthermore, these techniques are very useful to distinguish dissolved species from species bound to colloidal or particulate phases (Gonsalves et al., 1985). For recent applications see Bruland (1989, 1992), Donat and Bruland (1990), and Muller and Kester (1990, 1991). 

Xue, H. B., and Sigg, L. (1994) Zn Speciation in Lakewaters and Its Determination by Ligand Exchange with EDTA and DPASV, Anal. Chim. Acta 284, 505-515. 

Sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca), concentrations were measured by atomic absorption spectrophotometry (Perkin Elmer 2380 equipped with deuterium background corrector). Cd, Zr, and Cu concentrations were obtained in a quartz cell, by differential pulse anodic stripping voltammetry (DPASV) with a assy carbon thin-film mercury covered electrode (Tacussel polarographic equipment fitted with a Tacussel EDI type electrode). Pure water was produced by a Milli. Q water purification system (Millipore). Chlorate, sulfate and carbonate were measured using classical methods. 

The speciation of trace metals can be studied analytically using various fractionation schemes [ 2—5 ]. Metal species in solution can be arbitrarily classified by DPASV, as free ions and as both labile and nondabile conqdexed metal species. The species which are classified is nonJabile are non-electroactive under the experimental conditions... 

Table IV. Comparison of AA and DPASV Data for Massachusetts Bay Water"...

Electrode Performance. For the determination of copper, cadmium, and lead, the performance of the electrode was evaluated by continually recycling a 2-1. sample of San Diego Bay water for 129 consecutive analyses. During the last 22 determinations standard additions of copper, cadmium, and lead were made every third analysis. These additions increased the concentration of copper, cadmium, and lead in the sample by 1.0, 1.0, and 0.4 ppb respectively. All analyses were made by DPASV at pH 4.9 by sparging with carbon dioxide. The results of the consecutive determinations of copper and lead are presented in Figme 3. The relative heights of the trace metal peak currents are plotted on the ordinate as functions of the number of analytical determinations. The cadmium data are similar to that of copper and lead and have been omitted from the figure for clarity. 

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