Gino Bontempelli

University of Udine | UNIUD · Department of Agrifood, Environmental and Animal Science

A low-cost portable analytical device, suitable for performing reflectance measurements on paper supports is proposed. It consists of a simple module consisting of a matrix of six types of photodiodes (six channels) with maximum sensitivity at six different wavelengths in the visible region. The device was used in combination with paper-based analy...

A screen printed electrode modified for gas phase measurements is used for analyzing the ethanol content in alcoholic drinks. It consists in the application of a paper crown, soaked with the room temperature ionic liquid (RTIL) 1‐butyl‐3‐methylimidazolium hydrogen sulfate, upon a screen printed cell contacting the outer edge of the gold disc workin...

This investigation was carried out with the aim of verifying whether transmittance detection modes on soaked paper, which is a simple and attractive determination approach for microfluidic paper-based analytical devices, can be improved by using deep eutectic solvents (DESs) as suitable media for minimizing reflection and refraction phenomena affec...

Malondialdehyde (MDA) is a mutagenic secondary product of the peroxidation of polyunsaturated fatty acids, often used as a target for the food oxidation state, whose determination is frequently performed by its slow reaction with thiobarbituric acid (TBA), dissolved in acidified aqueous-ethanol medium, to produce a pink colored MDA-TBA adduct. In t...

This investigation was carried out with the aim of stressing that technologically-advanced systems can be prototyped and produced by using 3D printing and inexpensive electronic modules. In particular, open-source technologies are opening new exciting possibilities also in the area of chemical analysis, thus making possible the assembly of customiz...

We describe here a convenient assembly for screen printed carbon electrodes (SPCE) suitable for enabling analyses in gaseous samples which are of course lacking in supporting electrolytes. This assembly consists of a circular crown of filter paper, soaked in a RTIL or a DES, placed upon a disposable screen printed carbon cell, so as to contact the...

A rapid and user‐friendly approach is here presented for assembling smart and versatile platforms for simultaneous electrochemical and spectrophotometric measurements. They consist of an optically transparent pencil‐drawn electrochemical cell, including reference, counter and working carbon electrodes, assembled on flexible PVC supports, exploiting...

A simple, effective and low-cost technique is here presented for assembling flexible and robust electrochemical devices on transparent PVC supports, using ordinary tools, all installed on a commercial desktop digitally controlled plotter/cutter. Small diamond burs were first set up to rough precise and well defined patterns on the surface of smooth...

A simple and sensitive device is presented based on the use of pencil-drawn paper based electrochemical detector placed at the end of a cotton thread fluidic channel in wall-jet configuration. This innovative and fast responding electroanalytical system can be adopted for both single and dual electrode electrochemical detection, this last achieved...

A simple, reliable and low-cost fabrication method is here proposed for assembling paper-based electrochemical devices using a commercial desktop digitally controlled plotter/cutter, together with ordinary writing tools. Permanent markers (tips of 1 mm) were used to create effective hydrophobic barriers on paper, while micro-mechanical pencils (mou...

Gluten analysis is still affected by the lack of an efficient and universal extraction solvent for gliadin, i.e., the prolamine fraction of gluten which is the analytical target used to quantify gluten in food. In this investigation, the possibility of adopting pure choline chloride deep eutectic solvents (ChCl-DESs) as gliadin extraction media was...

A simple, sensitive and fast responding device is described for the discrimination of hydrophilic ortho-diphenols, whose presence in abundant enough amounts is typical for extra virgin olive oils (EVOOs), from hydrophilic mono-phenols instead present in almost all vegetable oils. It consists of a dual electrode detector pencil-drawn at the end of a...

The possibility of adopting deep eutectic solvents (DESs) instead of room temperature ionic liquids (RTILs) in membrane-free electrochemical gas probes was estimated by first evaluating the performance of ethaline as electrochemical medium. This very easily prepared DES was chosen as prototype since it displays high conductivity and fairly modest v...

The growing demand for low cost and easy to use analytical devices requires the development of reliable and rapid deposition strategies suitable for changing easily planned designs and applicable to a wide range of materials for assembling conductive tracks and sensitive elements. Further important challenges to be pursued are the possibility of us...

We propose here simple electrochemical cells assembled with electrodes pencil drawn on paper for conducting one-spot tests enabling olive oil to be easily distinguished from other vegetable oils. They consist of small circular pads of hydrophilic paper defined by hydrophobic barriers, these last printed by using custom-designed rubber stamps, where...

We propose here a quick and easy procedure for preparing pencil leads doped with Ag and AgCl suitable for the reproducible and easy drawing on paper or other porous supports of carbon based Ag/AgCl conductive lines for the use as reference electrodes. They were prepared by careful electrodeposition of silver and silver chloride on carbon powder (co...

A gas sensors based on a room temperature ionic liquid (RTIL) supported on paper is proposed as amperometric sniffer for monitoring volatile amines (VAs) released from fish samples, in order to gain indication of their state of turning spoiled. It was used as a paper electrochemical detector (PED) for a flow injection system in which controlled hea...

A simple strategy is here described for assembling graphite-based pencil leads doped with electrode modifiers suitable for drawing electrochemical devices on porous materials such as paper in a very reproducible and easy way. They were prepared by mixing controlled amounts of the chosen modifier with different quantities of carbon powder (conductiv...

AbstractA simple method is described to discriminate between analytes comigrating under on‐plate separation conditions, whose electrochemical behavior displays different reversible characters. It is based on the use of dual electrode detectors pencil‐drawn at the end of paper‐based fluidic channels defined by hydrophobic barriers. Simultaneous dete...

A simple procedure for preparing inexpensive paper-based three-electrode electrochemical cells is here described. They consist of small circular pads of hydrophilic paper defined by hydrophobic barriers printed on paper with wax-based ink. The back face of these pads is insulated by thermally laminating a polyethylene layer and working, reference a...

An array of quartz crystals coated with different room-temperature ionic liquids (RTILs) is proposed for the analysis of flavors by quartz crystal microbalance (QCM) measurements. Seven RTILs were adopted as sensing layers, all containing imidazolium or phosphonium cations, differing from one another in the length and branching of alkyl groups, and...

A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon wh...

A conveniently assembled membrane-free amperometric sensor is proposed for the detection of oxygen in gaseous atmospheres which exploits some profitable properties of room temperature ionic liquids (RTILs), such as their high electrical conductivity, negligible vapour pressure and good thermal stability. The advantages offered by this type of mediu...

AbstractA conveniently assembled, sensitive and fast‐responding membrane free amperometric sensor is described for the detection of nitrogen oxides in gaseous atmospheres which exploits some profitable properties of room temperature ionic liquids (RTILs), such as high electrical conductivity, negligible vapor pressure and good thermal stability. It...

A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure o...

The use of a mixed-valent ruthenium oxide/hexacyanoruthenate polymeric film electrochemically deposited onto glassy carbon electrodes is proposed here for the detection of biogenic amines and their amino acid precursors, following their separation by microchip capillary electrophoresis. The ability of this ruthenium coating to electrocatalyze the o...

Based on preliminary voltammetric investigations at unmodified and modified electrodes in aqueous solutions buffered at different pHs, a profitable thin layer dual-electrode detector was developed for the selective and simultaneous determination of ascorbic acid (AA) and hydrogen peroxide present in the same samples. It consists of a small thicknes...

A simple hydrodynamic injection method is proposed here for microchip CE coupled to electrochemical detection. It is based on the use of a precise syringe pump to push the sample into the microfluidic circuit, accompanied by the application of a secondary electric field to the injection channel, soon after the end of the injection step. In such a w...

A porous gold electrode supported on one face of an ion-exchange membrane, acting as a solid polymer electrolyte (SPE), is proposed as an amperometric sniffer for monitoring the aldehyde content in the headspace in equilibrium with lipid samples, in order to gain indication of their state of turning rancid It was used as a detector for a flow injec...

A sensitive and fast responding electrochemical sensor is described for the determination of free and total sulphur dioxide in wines and grape juices which prevents interferences coming from ethanol and other natural components. It consists of a cell provided with a porous gold working electrode supported on one face of an ion-exchange membrane, ac...

This article reports the procedure adopted to perform linear sweep voltammetry (LSV) and cyclic voltammetry (CV) and summarizes the main information obtained using these electrochemical techniques. In particular, a general overview of the considerable insight into electrochemical processes that can be gained using LSV and CV experiments is presente...

A method based on microchip electrophoresis with electrochemical detection has been developed for the simultaneous determination at trace levels of the main small-chain aldehydes (formaldehyde, acetaldehyde and 2-propenal) present in the atmosphere. Sampling was performed by forcing atmospheres through silica-gel cartridges coated with 2,4-dinitrop...

A linear sweep voltammetric (LSV) approach is proposed for achieving rapid information on metal release from tinned containers into preserved vegetables. Chopped tomato and pea preserves were chosen as prototypes for acid and nearly neutral canned food, respectively. Metal release in these vegetables tinned into both bare and lacquered containers w...

An improved single step microwave digestion procedure is described for providing the fast and easy exhaustive mineralisation of biological samples concomitantly with the quantitative conversion of any type of selenium compounds into Se(IV). In such a way, digested samples are directly suitable for the subsequent Se analysis at trace and ultratrace...

A method, based on microchip electrophoresis with electrochemical detection, has been developed for the simultaneous determination of light aliphatic aldehydes (acetaldehyde, propionaldehyde, butyraldehyde and hexylaldehyde) derivatized with 2,4-dinitrophenylhydrazine (DNPH). Optimal conditions for the derivatization reaction, providing recoveries...

A method based on microchip electrophoresis with electrochemical (EC) detection has been developed for the simultaneous determination of Yellow AB, Red 2G, Sunset Yellow, New Coccine, and Amaranth which are azo-dyes frequently added to foodstuffs. Factors affecting both separation and detection processes were examined and optimized, with best perfo...

A conveniently assembled probe is here proposed for the electrochemical detection of the phenol index (total volatile phenols) in wastewaters, which exploits some advantageous properties of ionic liquids (ILs), such as their negligible vapor pressure, good electrical conductivity and ability to dissolve a wide range of organic and inorganic compoun...

An in-channel configuration for amperometric detection has been adopted in capillary electrophoresis performed in photolithographically microfabricated chips. This electrode alignment, compared with the more conventional end-channel configuration, led to a better peak resolution and a higher sensitivity, because it involves no gap between the chann...

Based on preliminary voltammetric investigations at both Pt and Au electrodes in aqueous solutions buffered at different pH values in the range 0–10, two possible profitable triple-pulse amperometric approaches were developed for determining simultaneously peroxyacetic acid (PAA) and hydrogen peroxide present in the same samples. At both surfaces a...

A reverse-phase HPLC method for the simultaneous determination of the main artificial sweeteners, preservatives and dyes present in soft drinks is proposed. It involves the use of a 10 μm LiChrosorb RP18 column and a binary eluent consisting of aqueous 0.1 M phosphate buffer (pH 4.0) added with methanol, according to a suitable gradient elution pro...

A piezoelectric immunosensor is described which consists of a gold filmed quartz crystal, whose surface is modified with a thin Nafion layer entrapping known amounts of the specific antibody. This layer was applied by droplet evaporation on the gold surface of a mixture prepared by mixing a stock ethanol solution of Nafion with a stock antibody sus...

Drinkable water supplied by aqueducts undergoes preliminar potabilization which, in Italy, is mainly accomplished by chlorine addition. The bactericidal action involved in this process is always accompanied by chlorination and oxidation of organic species (mainly humic and fulvic acids) naturally present in treated waters, so that many disinfection...

A conveniently assembled electrochemical cell, exploiting a porous electrode supported on a moist perfluorinated ion-exchange polymer, is proposed for profitable electrochemical detection in supercritical fluid chromatography. It consists of a porous Pt working electrode, contacted by the mobile phase from the chromatographic column, which is chemi...

Cathodic stripping voltammetry (CSV), ion-chromatography (IC) and spectrophotometry (SP) have been tested as instrumental approaches alternative to inductively coupled plasma mass spectrometry (ICP-MS) for the determination of inorganic bromide residues in foodstuffs fumigated with brominated pesticides and digested by a suitably improved microwave...

The antioxidant capacity of some calcium antagonists and one calcium agonist 1,4-dihydropyridines (DHPs) was evaluated by a competitive kinetic procedure. With the exception of Amlodipine, all the calcium antagonist DHPs display an unambiguous antioxidant capacity, while for the calcium agonist DHP (Bay K 8644) no measurable reactivity towards pero...

The quenching of superoxide ions, O2.-, by curcumin has been studied by electrogenerating this anion radical from oxygen dissolved in acetonitrile solvent (that is, at best, a mimic of the lipofilic layer of biological membranes), containing known amounts of curcumin. Voltammetric tests, combined with coulometric and spectrophotometric measurements...

The release of heavy metals from uncovered and nickel-covered brass pumps has been evaluated by ICP-MS analysis in both simple ultrapure water and 3% acetic acid solution (mimic of neutral and acid edible liquids, respectively), following a procedure similar to that recommended by the National Sanitation Foundation (NSF) International, Test Procedu...

An amperometric sensor is described which is suitable for the continuous monitoring of traces of hydrogen peroxide present in workplace atmospheres as gaseous species or as aerosols, without preliminary concentration steps being needed. It consists of a porous Pt sensing electrode, facing the sample, chemically deposited onto one side of a Nafion®...

An improved microwave digestion procedure is described for the inductively coupled plasma mass spectrometric (ICP-MS) determination of inorganic bromide residues in foodstuffs fumigated with methyl bromide. It is based on the addition to the usual acid oxidizing mixture of small amounts of silver ions which cause bromides from the mineralized matri...

The redox properties of lacidipine (PyH2), one of the most pharmacologically active N-unsubstituted 1,4-dihydropyridines, have been studied by cyclic voltammetry and controlled potential electrolysis in acetonitrile, an aprotic solvent that is, at best, a mimic of the lipofilic layer of biological membranes. PyH2 undergoes a two-electron oxidation...

The effect on the formation of both oxygenated polyatomic and doubly charged ions in inductively coupled plasma mass spectrometry (ICP-MS) has been evaluated for sample introduction with three different injection devices. An ultrasonic nebulizer (USN) equipped with an efficient membrane desolvator, in addition to a usual desolvation module incorpor...

A perfluorinated ion-exchange membrane-based sensor suitable for electroanalytical measurements in electrolyte-free media is described, which is assembled following a novel design enabling an easier preparation procedure. It is fabricated by inserting the terminal portion of a working wire electrode into a Nafion tubing of suitable diameter and wel...

A simple method for the analysis of nanoliter droplets is proposed, which is profitable when larger samples cannot be collected as, for instance, in the case of several biological fluids and particularly in clinical chemistry. A glass capillary associated to a micromanipulator is used to collect submicroliter volumes which are partially transferred...

Electroanalytical sensors, suitable for the analysis and monitoring of electroactive analytes present in gaseous phase or low-conductive liquid media, and based on electrodes in close contact with perfluorinated ion-exchange polymers are reviewed. The basic operative mechanism of these sensors, in which ion-exchange polymers act as solid polymer el...

A sensitive and fast-responding amperometric sensor for the determination of ethanol in breath which eliminates oxygen interferences is described. It consists of a porous gold working electrode (facing the sample) supported on one face of an ion-exchange membrane which serves as a solid polymer electrolyte (SPE). The other side of the membrane face...

An amperometric sensor is described for the determination of peroxides in both aqueous and organic media. It consists of a rotating glassy carbon electrode modified by coating first with a thin film of a perfluorinated anionic exchanger (Tosflex) and then by immobilizing on this substrate the mixed-ligand copper complex [CuL2]2+ with 1, 10-phenanth...

The properties of poly-2,5-pyridine films, deposited on gold electrodes through a nickel-catalyzed cathodic polymerization route carried out in acetonitrile, were re-investigated by electrochemical quartz crystal microgravimetry in conjunction with cyclic voltammetry and coulometry. Special attention was paid to the ion transport during film reduct...

A highly sensitive and fast-responding electroanalytical sensor for the determination of hydrogen sulfide in gaseous atmospheres is described which eliminates oxygen interferences. It consists of a porous silver working electrode (facing the sample) supported on one face of an ion-exchange membrane, which serves as a solid polymer electrolyte. The...

Voltammetry at electrodes modified with ion-exchange polymers, named "ion exchange voltammetry", has been recently developed for characterizing and determining quantitatively ionic electroactive analytes preconcentrated at the electrode surface. Like for other voltammetric techniques, characterization is based on the position of the response on the...

A procedure for the simultaneous microdetermination of chlorine, bromine and phosphorus in organic compounds is described. It consists of ion chromatographic analysis, after suitable dilution, of the solution resulting from the collection in water containing hydrogen peroxide of the combustion products obtained by decomposition of the sample in a S...

A solid state cell proposed elsewhere, enabling the extension of ion exchange voltammetry to trace determination of small ionic species with low ion exchange selectivity coefficients, dissolved in electrolyte-free media, has been adopted to verify whether the degrees of preconcentration achieved with such a voltammetric technique actually increase...

A solid-state cell is described that allows the extension of ion-exchange voltammetry to the trace determination of small ionic species characterized by low ion-exchange selectivity coefficients, provided that they are dissolved in electrolyte-free media. It consists of a wetted ion-exchange membrane (Nafion), one face of which contacts both the co...

An amperometric sensor is described for the determination of sulphur dioxide in both gaseous atmospheres and solutions of low conductivity. It consists of a porous Pt electrode (facing the sample) supported on one face of an ion-exchange membrane (Nafion 417) which serves as a solid polymer electrolyte. The other side of the membrane faces an inter...

A gas chromatographic system for the evaluation of linear temperature-programmed retention indices allowing n-alkanes to be adopted as the reference retention markers for any type of analyte, irrespective of the atoms present in their molecules, is described. It is based on the simultaneous use of two different detectors (a flame ionization detecto...

An electroanalytical device is described that is suitable for trace metal analysis by anodic stripping voltammetry (ASV) in highly-resistive media in the absence of supporting electrolytes. It consists of a thin mercury film electrodeposited at the glassy carbon-ion-exchange membrane interface obtained by clamping a glassy carbon ring to one surfac...

A sensitive and simple method is described for the selective determination in human plasma of alpha-amanitin, the most poisonous and prevalent toxin in the lethal fungi of species Amanita, using high-performance liquid chromatography with amperometric detection. After an extraction of plasma with disposable C18 silica cartridges, the extracts were...

The electrochemical reduction of a series of high-spin octahedral complexes of nickel(II) with a variety of Schiff base ligands of the type RNCHPy (Py=pyridyl; R=CH3; C6H5; o-, m- or p-CH3-C6H4; o-, m- or p-ClC6H4; o-, m- or p-CH3O-C6H4) has been investigated in acetonitrile. All these complexes undergo a fairly reversible two-electron reductio...

An in situ amperometric sensor suitable for monitoring ozone in gaseous media is described. It consists of a porous gold working electrode (contacting the gaseous sample) supported on one surface of an ion exchange membrane (Nafion 417) which serves as a solid polymer electrolyte. The other side of this membrane faces an internal electrolyte soluti...

An electroanalytical sensor is proposed that is suitable for the detection of electroactive analytes present in gases or low-conductivity solvents where supporting electrolytes cannot be introduced. It consists of a porous working electrode supported on one surface of a cationic ion-exchange membrane (Nafion 417), the other surface of which is in c...

Review: (fundamentals, theory, computational methods, comparison of experimental and theoretical responses and an appendix containing differential equations as well as initial and boundary conditions for different electrode mechanisms; 125 refs.

The electrochemical oxidation of 1-naphthylamine at platinum electrodes has been investigated in dimethyl sulphoxide. Such a process occurs through a pathway involving a very fast chemical reaction interposed between two one-electron charge transfers. The kinetic constant of this chemical step is inaccessible to voltammetric measurements performed...

The electroanalytical method described for the simultaneous determination of concentration, the number of electrons involved in the redox process and diffusion coefficient is based on evaluation of the ratios between the currents recorded for the analyte and for an easily standardized reference species dissolved in the same medium. Three different...

A nickel-catalysed electrochemical method for the synthesis of poly-2,5-pyridine is suggested. It is based on the reduction of 2,5-dibromopyridine carried out by generating electrochemically and continuously recycling nickel(0) from nickel(II) in the presence of both bipyridyl and triphenyl-phosphine. The simultaneous presence of these ligands is r...

The soft–hard mixed-ligand complexes [M(acac)(dppe)]+[M = Ni or Pd, acac = acetylacetonate, dppe = 1,2-bis(diphenylphosphino)ethane] have been characterized by a combination of electroanalytical and spectrophotometric measurements. These species can easily be synthesized in acetonitrile both by a ligand conproportionation reaction upon starting fro...

The relative basicity of some organic solvents of electroanalytical interest (propylene carbonate, sulfolane, 2-methyltetrahydrofuran, methyl formate and morpholine) is evaluated by cyclic voltammetry. Anhydrous perchloric acid is electrogenerated in these solvents and the half-wave potentials of the redox couple H+/H2 are recorded by referring the...

Aromatic diamine hydrochlorides have been determined in the presence of different amounts of hydrochloric acid by acid-base titration followed potentiometrically, by linear sweep voltammetry, by differential pulse voltammetry and also by direct DPV measurement. Tests on simulated and production samples have shown that the best results are obtained...

An easy procedure for the preparation of electrodes coated by poly-2,5-pyridine is described. It is based on the electrochemical reduction of the corresponding dibromopyridine in acetonitrile catalyzed by the nickel-bipyridyl complex. A combination of analytical and electrochemical tests points out that the film consists of a polyconjugated electro...

The interaction of both nesosteine and trans-sobrerol with O2•− has been studied by electrogenerating this anion radical in acetonitrile and monitoring voltammetrically its disappearance upon addition of the named mucofluidifier drugs. This approach makes it possible to establish that nesosteine acts as an effective sacrificial superoxide quencher,...

Summary Evidence for the ability of the electrogenerated cationic nickel(I) complex [Ni(PPh3)4]+ to promote the isomerization of allylbenzene is reported. However, the corresponding triethylphosphitenickel(I) complex displays no catalytic activity, apparently due to the poor leavinggroup character exhibited by the phosphite. The involvement of a p-...

The electrochemical reduction of carbon dioxide is strongly catalysed when it is carried out by cathodically generated and continuously recycling nickel(O) from the nickel(II)-bipyridyl precursor complex. In such a way, equimolar amounts of carbon monoxide and carbonate ions are obtained in a good yield referred to the charge transferred. However,...