30,307 research outputs found
Heavy metals determination by biosensors based on enzyme immobilised by electropolymerisation
No full textThe work describes the original application of biosensors based on enzyme immobilised by electropolymerisation to heavy metal determination.
An inhibition detection scheme has been employed for detecting Hg2+ by an established glucose biosensor based on glucose oxidase
immobilised in poly-o-phenylenediamine. The investigated enzymatic inhibition appears reversible and mixed, in agreement with data for
the enzyme in solution. A low response time (<2 min) and a rapid recovery of response by EDTA seem the most interesting characteristics
of the proposed biosensor at the present stage of development, along with the well known easy preparation of this kind of biosensors. The
occurrence of a high response also for Cu2+ opens the possibility to apply the biosensor in total toxic metal content determination
Determinazione di Hg++ mediante un biosensore basato su enzima immobilizzato elettrochimicamente
No full textAnalisi quantitativa in XPS (X-ray Photoelectron Spectroscopy): definizione ed applicazione di un parametro innovativo nella procedura di curve-fitting
No full textSulfide measurements by flow injection analysis and ion chromatography with electrochemical detection
No full textDissolved sulfide ions are separated and detected by using ion chromatography (IC) and electrochemical detection with a glassy carbon electrode modified by electrochemical deposition of palladium particles. The influence of various experimental factors such as pH, loading of palladium, applied potential and flow rate of mobile phase is evaluated. The effect of some common organic and inorganic compounds on the amperometric signal is also evaluated. Under optimal chromatographic conditions, the detection limit for sulfide (S/N=3) was 0.3μM (15pmol injected) and the calibration plot was linear for 0.5–350μM sulfide (r=0.9964, n=16). The separation and detection of sulfides in human blood serum is presented as an example of an application to real specimens
XPS Study and Electrochemical behaviour of the Nickel Hexacyanoferrate Film Electrode upon Treatment in Alkaline Solution
No full textAbstract: This paper describes the X-ray photoelectron spectroscopy (XPS) characterisation and voltammetric behaviour of nickel hexacyanoferrate (NiHCF) film electrodes. Glassy carbon was used as a substrate and was modified by cycling the potential between -0.1 and +0.9 V vs. SCE in fresh 0.5 M KCl solutions containing 0.25 mM NiCl2 and 0.25 mM K3Fe(CN)(6). Subsequent electrochemical cycling of the NiHCF film in alkaline solutions induces significant changes, yielding a modified electrode that is primarily composed of hydrated Ni(II) oxide/hydroxide with a single set of well-defined Ni(II)/(III) voltammetric peaks. Such induced changes are irreversible, and the XPS investigation was very useful for verifying the electrode modifications occurring. Iron present in the NiHCF film suffered the most changes. The absolute intensity of the Fe2p and N:K elemental ratio were especially useful in evaluating the modifications occurring, providing a clear indication of the extent to which NiHCF film was converted. The implications of these findings are discussed
Electrochemical Preparation of a Composite Gold-Cobalt Electrode and its Electrocatalytic Activity in Alkaline Medium
No full textAbstract: A chemically modified electrode composed of cobalt(III) oxyhydroxide film dispersed on the gold substrate (Au-Co) was characterised by cyclic voltammetry. Electrochemical deposition of the cobalt film was accomplished by cycling the potential between 0.0 V and 1.1 V (vs. saturated calomel electrode (SCE)) in 0.1 M acetate solution (at pH 7.3) containing 10 mM CoCl2. The effects of several experimental parameters (pH, applied potentials, etc.) on the film formation and growth were evaluated. The electrochemical behaviour of the Au-Co composite electrode was investigated in alkaline medium. The film appears uniform and compact and shows good electrical conductivity and electrochemical activity towards the oxidation of several scarcely electroactive organic molecules. The concomitant presence on the electrode surface of both active catalysts leads to a wide range of potential applications where a significant electrochemical activity towards the electrooxidation of several classes of organic compounds is observed. (C) 1999 Elsevier Science Ltd. All rights reserved
Anodic Electrodeposition of Conducting Cobalt Oxyhydroxide Films on a Gold Surface. XPS Study and Electrochemical Behaviour in Neutral and Alkaline Solution
No full textAbstract: A novel chemically modified electrode prepared by anodic electrodeposition of cobalt (III) film on the gold electrode substrate (Au-Co) was characterised by cyclic voltammetry and XPS techniques in both neutral and alkaline medium. Cobalt oxyhydroxide film was deposited by cycling the potential between 0.0 and 1.1 V versus SCE in 0.1 M sodium acetate solutions containing 10 mM CoCl2. The electrocatalytic properties of the Au-Co electrode were investigated in alkaline medium using glucose as a model compound. A comparative XPS study of bare gold, bare cobalt and Au-Co electrodes after electrochemical treatment in neutral and alkaline solutions has been carried out. A detailed XPS analysis of the Au4f(7.2), Co2p(3.2), O1s and C1s regions was performed to check the chemical composition of the Au-Co electrode upon electrochemical treatments. Film deposition is attributed to growth of conducting and compact CoOOH oxyhydroxide with significant insertion of carbonyl groups within the electrodeposited layer. The prolonged electrochemical treatment in alkaline medium produces a good stabilization of the Co-III oxyhydroxide film, with a dominant O1s feature at about 532.4 eV of BE corresponding to a non-stoichiometric surface oxygen. The absence of CoO species proves good conducting properties of the cobalt film and the absence of any passivation effects on the catalytic performance. (C) 1999 Elsevier Science S.A. All rights reserved
Analytical application of an amperometric biosensor based on glucose oxidase inhibition for the determination of heavy metal ions
No full textItinerario Rosa, Tavola Rotonda sul tema «Quando la tecnologia imita la natura: anche fra macchina e corpo l’integrazione nasce dal dialogo» I progressi della biosensoristica applicata alla medicina.
No full textLa manifestazione è organizzata ogni anno dal Comune di Lecce per la valorizzazione il ruolo sociale e culturale della donna. https://www.comune.lecce.it/news/2017/02/27/tutti-gli-eventi-in-programma-per-itinerario-rosa La tavola rotonda è stata inserita dalla settimana della cultura scientifica dell'Università del Salent
Caratterizzazione Spettroscopica XPS ed Elettrochimica di Film Langmuir-Schäfer Basati Su 2-Cloroetossi-Ferro-Etilsulfanilporfirazina
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