1,721,067 research outputs found
Valutazione della Presenza di Farine Animali nei Mangimi per Ruminanti mediante la Determinazione della Carnosina utilizzando la Cromatografia Ionica con Rivelazione Amperometrica Pulsata (HPAEC-IPAD)
No full textDeterminazione dell’Acido Orotico in Matrici Reali mediante Cromatografia Ionica e Rivelazione Amperometrica Pulsata
No full textDetermination of Carnosine in Feeds and Meat Samples by High-Performance Anion-Exchange Cromatography with Integrated Pulsed Amperometric Detection
No full textCarnosine (-alanyl-l-histidine) is a dipeptide regarded as an important molecular marker of the presence of processed animal proteins including meat and bone meal in animal feed. For its identification and quantification a sensitive and selective method by high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection (HPAEC–IPAD) was developed. The assay is based on isocratic elution with 100mM NaOH as the mobile phase. Interferences of real matrices were efficiently removed; carnosine could be determined at the concentration ranges 0.1–100 uM with a rather low detection limit of 0.23 ng. Unlike feeds for dogs and cats, no carnosine peak was observed in all examined feeds for ruminants. The good analytical characteristics allowed carnosine determination down to 5 ug/g of feed
Electrocatalysis and amperometric detection at a ruthenium-modified indium-hexacyanoferrate film electrode
No full textThe electrocatalytic activity of a glassy carbon electrode modified with electrochemically deposited indium(III)-hexacyanoferrate (InHCF) film, which has been subsequently cycled in a solution of ruthenium(III), is described. Although the resulting ruthenium-modified InHCF thin film electrode behaves in a manner analogous to the parent InHCF film, its stability was found to be greatly improved. Such a modified electrode was characterized, in acidic (pH 2) 0.5 M KCl solutions, by cyclic voltammetry and flow injection analysis. It exhibits a high catalytic activity for the electrooxidation of some some inorganic and organic compounds of analytical interest, such as As(III), S2O32-, cysteine, and 2-furaldehyde. The analytical applicability of this novel ruthenium-modified InHCF film electrode for the amperometric detection in flowing streams is discussed. Repetitive sample injections with amperometric detection of thiosulfate at +0.8 V (vs. Ag/AgCl) as applied potential produced a stable response over 8 h of operation, making it very attractive for practical applications
Permselective Behaviour of an Electrosynthesized, Non-Conducting Thin Film of Poly(2-Naphthol) and Its Application to Enzyme Immobilization.
No full textQuantitative Determination of Taurine in Real Samples by High-Performance Anion-Exchange Chromatography with Integrated Pulsed Amperometric Detection
No full textAs taurine is a very important compound involved in a large number of metabolic processes, it is naturally present in the mammal tissues and is often deliberately added in some foods as a fortifying component. A detailed knowledge of taurine metabolic roles in biological systems can be obtained only if a sensitive, reliable and rapid analytical method is available. This article describes the successful application of high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection (HPAEC-IPAD) for taurine determination in egg white and yolk samples, as well extracts of human serum and urine. Applications are shown for determination of taurine in soft drinks and pharmaceutical preparations where the taurine content was evaluated by standard additions. These results were achieved without prior derivatization of taurine
Oro polidisperso in forma colloidale su matrice grafitica come sensore amperometrico per la determinazione di carboidrati
No full textSviluppo di un Nuovo Metodo di Analisi della Biotina mediante Cromatografica a Scambio Anionico e Rivelazione Amperometrica Pulsata (HPAEC-PAD)
No full textElectrochemical quartz crystal microbalance study and electrochromic behavior of a novel ruthenium purple film
No full textThin films of ferric-ruthenocyanide, also known as ruthenium purple (RP) can be readily prepared by repetitive potential cycling onto a number of different conducting materials such as glassy carbon, gold, platinum and indium-tin-oxide (ITO). This procedure is successfully accomplished provided that the supporting electrolyte, containing 0.5 mM FeCl3 + 0.5 mM K4Ru(CN)(6), is moderately concentrated in potassium electrolytes, i.e. 40 mM KCl + HCl at pH 2. Electrode stability of RP films was found greatly enhanced by cycling the inorganic film in millimolar solutions of RuCl3. The resulting Ru(III)-RP film shows a single set of well-defined peaks with anodic and cathodic peak potentials at +0.26 V, and +0.14 V vs. SCE, respectively. Its voltammetric profile remains unchanged after ca. 1500 oxidation-reduction cycles at 50 mV/s (14 h of potential cycling). The stabilisation process in RuCl3 solutions of as-grown RP films on platinum coated quartz crystals was followed concurrently by electrochemical quartz crystal microbalance (ECQM). The absorption spectra of the film on a ITO-covered glass electrode polarised to +0.50 V exhibits an absorption band at about 545 nm. The electrochromic activity and ease of preparation of Ru(III)-RP film electrodes makes them good candidates for electrochromic appliances. (C) 1997 Elsevier Science S.A
Assay of Riboflavin in Sample Wines by Capillary Zone Electrophoresis and Laser-Induced Fluorescence Detection
No full textTo routinely assay the concentration of riboflavin (RF) in wines, a rapid and sensitive method was developed and evaluated. The method is based on a simple sample preparation, capillary zone electrophoretic separation and laser-induced fluorescence detection (CZE-LIF). Sample preparation required only dilution and filtration. Under optimized conditions, the limit of detection of riboflavin was 0.5 íg/L, using a hydrodynamic sample introduction of 10 s at 54 mbar. The method was fully validated: the recovery of RF in wines was >95%. The concentrations of RF within the three sample types of Italian wines investigated here ranged from 69 to 151 íg/L with a mean value ((SD) of 112 ( 25 íg/L, from 74 to 193 íg/L with a mean value of 115 ( 45 íg/L, and from 156 to 292 íg/L with a mean value of 226 ( 40 íg/L, for white, rose ́ , and red wines, respectively. Such an accurate and highly sensitive CZE-LIF method represents a powerful improvement over previous methods in terms of sensitivity, simplicity, and efficiency. It is well suited to satisfy the demands for accurate and sensitive detection with minimal sample preparation and cleanup
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