| 1. |
- Arrigan, Damien, et al.
(författare)
-
Selective voltammetric detection of dopamine in the presence ofascorbate
- 2004
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; :6, s. 732-733
-
Tidskriftsartikel (refereegranskat)abstract
- The selective detection of dopamine in the presence of ascorbateis demonstrated based on the voltammetry of dopamine transferacross the interface between two immiscible electrolyte solutions(ITIES) facilitated by an organic-phase ionophore; ascorbatetransfer does not occur, leading to highly selectivedetection of dopamine in the presence of excess ascorbate.
|
|
| 2. |
- Beni, Valerio, et al.
(författare)
-
Cyclic and pulse voltammetric study of dopamine at the interfacebetween two immiscible electrolyte solutions
- 2005
-
Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 20:10, s. 2097-2103
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at the interface between twoimmiscible electrolyte solutions (ITIES) has been studied. Voltammetry at the liquid/liquid (water/1,2-dichloroethane) interface provides asimple method for overcoming the major problem associated with dopamine detection by voltammetry at solid electrodes: the co-existenceof ascorbate at higher concentrations. Selectivity for dopamine was achieved by the use of dibenzo-18-crown-6 as an ionophore for thefacilitated transfer voltammetry of protonated dopamine across the ITIES. Under these conditions, ascorbate is not transferred and hence doesnot interfere in the ion transfer current for dopamine. By use of DPV and SWV, the lowest concentration detectable can be lowered from ca.0.1mM (obtained with cyclic voltammetry) to 2 M. Evaluation of the effect of some other physiologically important species (acetylcholine,sodium, potassium and ammonium ions) on the dopamine transfer voltammetry has been studied, indicating the need for improved ionophoredesigns in order to achieve practically useful selectivity.
|
|
| 3. |
- Beni, Valerio, et al.
(författare)
-
Development of a portable electroanalytical system for the stripping voltammetry of metals : Determination of copper in acetic acid soil extracts
- 2005
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 552:1-2, s. 190-200
-
Tidskriftsartikel (refereegranskat)abstract
- The development, characterisation and evaluation of a prototype portable electrochemical trace metal analyser are presented. The instrumentis a battery-powered microcontroller-based potentiostat, which implements anodic stripping voltammetry (ASV) at suitable sensor electrodes.It is capable of operating away from the laboratory, in the absence of an external power source and is usable by low-skilled personnel. Thedistinguishing feature of the instrument is its custom software, which enables sample pre-screening, data processing and sample dilution andstandard additions calculations to be carried out. The instrument has been evaluated by application of a methodology for the detection ofcopper in acetic acid soil extracts, both in the laboratory and in the field. Underpotential deposition staircase anodic stripping voltammetry(UPD-SCASV) of the copper at gold disk electrodes was used as a test method. There was good agreement between the instrument resultsand those from laboratory-based reference analytical methods for analyses carried out both in the laboratory and in the field.
|
|
| 4. |
- Beni, Valerio, et al.
(författare)
-
Electrochemical properties of polymeric nanopatterned electrodes
- 2007
-
Ingår i: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 9:7, s. 1833-1839
-
Tidskriftsartikel (refereegranskat)abstract
- An investigation of the electrochemical behaviour of gold electrodes coated with poly(ethylene glycol) (PEG), poly(acrylic acid)(PAA) and nanopatterned PAA/PEG layers is presented. Plasma-enhanced chemical vapour deposition and colloidal lithography wereused to produce nanodomes of PAA in a matrix of PEG. The electrochemical response at these nanostructured electrodes was studied asa function of the probe ion charge. Results show that the film structures allow the electrodes to retain their electrochemical activity whileminimising surface fouling and will thus be useful in the development of electrochemical nanobiosensors for various applications.
|
|
| 5. |
- Beni, Valerio, et al.
(författare)
-
Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media
- 2011
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 699:2, s. 127-133
-
Tidskriftsartikel (refereegranskat)abstract
- The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuricacid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The bestvoltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte.The concomitant presence of metals, such as copper or lead, and of model biomolecules, suchas bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response forselenium(IV). Quantitative detection of selenium(IV) by square wave anodic stripping voltammetry atboth a millimetre-sized gold disc electrode and a microband electrode array revealed linear responsesto selenium concentration in the ranges 5–15 M and 0.1–10 M, respectively, with 60 s preconcentration.The sensitivities were 6.4 A M−1 cm−2 and 100 A M−1 cm−2 at the disc and the microband array,respectively. The detection limit at the microband electrode array was 25 nM, illustrating the potentialityof such microelectrodes for the development of mercury-free analytical methods for the trace detectionof selenium(IV).
|
|
| 6. |
- Beni, Valerio, et al.
(författare)
-
Microelectrode arrays and microfabricated devices in electrochemical stripping analysis
- 2008
-
Ingår i: Current Analytical Chemistry. - : Bentham Science Publishers. - 1573-4110 .- 1875-6727. ; 4:3, s. 229-241
-
Tidskriftsartikel (refereegranskat)abstract
- In this article a comprehensive overview of the developments in the field of electrochemical stripping analysis with microelectrode arrays and microfabricated devices is presented. Due to the vastness of the topic, this mini-review deals only with the use of regular microelectrode arrays. After the description of the main fabrication methodologies employed, a large part of the review is dedicated to applications, categorised by the electrode material. Microelectrode arrays have found application in several areas of electroanalytical science including clinical and environmental analysis. They have been used for the detection of heavy metals in waters, soil extracts and blood, proving to be reliable analytical devices and bringing the advantages of low-cost, simplicity of use and easy adaptability to field measurement. In many applications, limits of detection are sub-parts per billion. Finally a short section of the review discusses miniaturised potentiostats.
|
|
| 7. |
- Beni, Valerio, et al.
(författare)
-
Voltammetric behaviour at gold electrodes immersed in the BCR sequential extraction scheme media : Application of underpotential deposition–stripping voltammetry to determination of copper in soil extracts
- 2004
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 502:2, s. 195-206
-
Tidskriftsartikel (refereegranskat)abstract
- The development of mercury-free electroanalytical systems for in-field analysis of pollutants requires a foundation on the electrochemicalbehaviour of the chosen electrode material in the target sample matrices. In this work, the behaviour of gold working electrodes in the mediaemployed in the BCR sequential extraction protocol, for the fractionation of metals in solid environmental matrices, is reported. All three ofthe BCR sequential extraction media are redox active, on the basis of acidity and oxygen content as well as the inherent reducing or oxidisingnature of some of the reagents employed: 0.11M acetic acid, 0.1M hydroxylammonium chloride (adjusted to pH 2) and 1M ammoniumacetate (adjusted to pH 2) with added trace hydrogen peroxide. The available potential ranges together with the demonstrated detection oftarget metals in these media are presented. Stripping voltammetry of copper or lead in the BCR extract media solutions reveal a multi-peakbehaviour due to the stripping of both bulk metal and underpotential metal deposits. A procedure based on underpotential deposition–strippingvoltammetry (UPD-SV) was evaluated for application to determination of copper in 0.11M acetic acid soil extracts. A preliminary screeningstep in which different deposition times are applied to the sample enables a deposition time commensurate with UPD-SV to be selected sothat no bulk deposition or stripping occurs thus simplifying the shape and features of the resulting voltammograms. Choice of the suitabledeposition time is then followed by standards addition calibration. The method was validated by the analysis of a number of BCR 0.11Macetic acid soil extracts. Good agreement was obtained been the UPD-SV method and atomic spectroscopic results.
|
|
| 8. |
- Berduque, Alfonso, et al.
(författare)
-
Voltammetric characterisation of silicon-based microelectrode arrays and their application to mercury-free stripping voltammetry of copper ions
- 2007
-
Ingår i: Talanta. - : Elsevier. - 0039-9140 .- 1873-3573. ; 71:3, s. 1022-1030
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the electrochemical characterisation of a range of gold and platinum microelectrode arrays (MEAs) fabricated by standardphotolithographic methods. The inter-electrode spacing, geometry, numbers and dimensions of the electrodes in the arrays were found to influencethe voltammetric behaviours obtained. Excellent correlation was found between experimental data and theoretical predictions employing publishedmodels of microelectrode behaviour. Gold MEAs were evaluated for their applicability to copper determination in a soil extract sample, whereagreement was found between the standard analytical method and a method based on underpotential deposition—anodic stripping voltammetry(UPD-ASV) at the MEAs, offering a mercury-free alternative for copper sensing.
|
|
| 9. |
- Herzog, Gregoire, et al.
(författare)
-
Effect of humic acid on the underpotential deposition-strippingvoltammetry of copper in acetic acid soil extract solutions atmercaptoacetic acid-modified gold electrodes
- 2004
-
Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 511:1, s. 137-143
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemical measurements were undertaken for the investigation of the underpotential deposition-stripping process of copper at bareand modified gold electrodes in 0.11M acetic acid, the first fraction of the European Union’s Bureau Communautaire de Références (BCR)sequential extraction procedure for fractionating metals within soils and sediments. Gold electrodes modified with mercaptoacetic acid showedhigher sensitivity for the detection of copper than bare gold electrodes, both in the absence and in the presence of humic acid in acetic acidsolutions, using the underpotential deposition-stripping voltammetry (UPD-SV) method. In the presence of 50 mg l−1 of humic acid, themercaptoacetic acid modified electrode proved to be 1.5 times more sensitive than the bare gold electrode. The mercaptoacetic acid monolayerformed on the gold surface provided efficient protection against the adsorption of humic acid onto the gold electrode surface. Variation of thehumic acid concentration in the solution showed little effect on the copper stripping signal at the modified electrode. UPD-SV at the modifiedelectrode was applied to the analysis of soil extract samples. Linear correlation of the electrochemical results with atomic spectroscopic resultsyielded the straight-line equation y (g l−1) = 1.10x − 44 (ppb) (R = 0.992, n = 6), indicating good agreement between the two methods.
|
|
| 10. |
- Ogurtsov, Vladimir, et al.
(författare)
-
MINIATURIZED ELECTROCHEMICAL SENSING SYSTEMSFOR IN VITRO AND IN VIVO BIOMEDICAL APPLICATIONS
- 2009
-
Ingår i: BIODEVICES 2009. ; , s. 83-87
-
Konferensbidrag (refereegranskat)abstract
- Development of miniaturized electrochemical sensing systems for in vitro and in vivo biomedicalapplications is discussed. The systems are based on high sensitivity potentiostatic instrumentation, which issuitable for chemical and biochemical sensors. The in vitro application is an 8 channel hand-held PCcontrolledsystem with user-friendly interface. This is capable of implementing different electrochemicalpotentiodynamic techniques. The in vivo applications are realized using two approaches: a small sized PCBwith commercially available ICs, and a specially developed on-chip system. The performance of thesystems is validated through electrochemical characterization of a microarray sensor.
|
|
