A dithizone (DTZ) modified carbon paste electrode was developed for the sensitive and selective determination of Pb(II) using differential pulse anodic stripping voltammetry as well in batch as in FIA system. The analysis procedure is based on an open circuit accumulation step in a stirred sample solution. This was followed by a medium exchange to a clean solution and subsequently by a proper anodic stripping. The analytical performance was evaluated with respect to the quantity of modifier in the paste, accumulation time, background electrolyte, Pb(II) concentration and other variables. When the accumulation time applied was 5 minutes, linear calibration graphs were obtained in the concentration range 1 x 10(-7)-1 x 10(-5) M and 8 x 10(-8)-5 x 10(-6) M for batch and Flow Injection Analysis (FIA), respectively. The detection limits found were 8.65 x 10(-8) M in batch and 4.45 x 10(-8) M in FIA. A convenient and rapid renewal of electrode surface allows the use of a single modified electrode surface in multiple analytical determinations. Several coexisting metals ions such as Cd(II), Hg(II), Cu(II) and Zn(II) had no interference on the determination of Pb(II). The proposed method was applied in the determination of lead in soils located in the vicinity of metallurgic transformation industry. The results obtained were in accordance to the ones supplied by Atomic Absorption Spectroscopy (AAS).
"In addition, the excellent compatibility of electrochemical sensors with flow injection analytical systems (FIA) increases the potential for assay automation, to which more and more attention has been paid in many fields including food analysis (Mizutani et al 1998) and environmental monitoring (Vazquez et al 2006). One of the biggest challenges in designing a new enzymebased biosensor is to find the optimal balance between stability and activity of the enzyme. "
[Show abstract][Hide abstract] ABSTRACT: A stable and sensitive biosensor for phenol detection based on a screen printed electrode modified with tyrosinase, multiwall carbon nanotubes and glutaraldehyde is designed and applied in a flow injection analytical system. The proposed carbon nanotube matrix is easy to prepare and ensures a very good entrapment environment for the enzyme, being simpler and cheaper than other reported strategies. In addition, the proposed matrix allows for a very fast operation of the enzyme, that leads to a response time of 15 s. Several parameters such as the working potential, pH of the measuring solution, biosensor response time, detection limit, linear range of response and sensitivity are studied. The obtained detection limit for phenol was 0.14 x 10(-6) M. The biosensor keeps its activity during continuous FIA measurements at room temperature, showing a stable response (RSD 5%) within a two week working period at room temperature. The developed biosensor is being applied for phenol detection in seawater samples and seems to be a promising alternative for automatic control of seawater contamination. The developed detection system can be extended to other enzyme biosensors with interest for several other applications.
[Show abstract][Hide abstract] ABSTRACT: In this review (with 500 refs), both electrochemistry and electroanalysis with carbon paste-based electrodes, sensors, and
detectors are of interest, when attention is focused on the research activities in the years of new millennium. Concerned
are all important aspects of the field, from fundamental investigations with carbon paste as the electrode material, via laboratory
examination of the first electrode prototypes, basic and advanced studies of various electrode processes and other phenomena,
up to practical applications to the determination of inorganic ions, complexes, and molecules. The latter is presented in
a series of extensive tables, offering a nearly complete survey of methods published within the period of 2001–2008. Finally,
the latest trends and outstanding achievements are also outlined and future prospects given.
Central European Journal of Chemistry 12/2009; 7(4):598-656. DOI:10.2478/s11532-009-0097-9 · 1.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity detections are most commonly employed in capillary electrophoresis.
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