Nafion® as advanced immobilisation substrate for the voltammetric analysis of electroactive microparticles: the case of some artistic colouring agents

Abstract

Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating. The analyte studied in this work is Prussian Blue as a typical inorganic pigment, with a relatively simple electrochemical behaviour. The proposed method is applied to a sample of Venetian marmorino plaster. The performance of Nafion® for this analysis is compared with that of the polymer Paraloid B72.

Characterization of Costa Rican Archaeological Ceramics From the Formative Period: Preliminary Electrochemical Studies

“…Due to the small intensity of the signals observed in the CV with the other type of electrodes, square wave voltammetry (SWV) was used. This technique allows analysis in samples where the signal/noise ratio is too low by CV (Bard and Faulkner 2001;Moretto et al 2013).…”

Chemical analysis and computed tomography of metallic inclusions in Roman glass to unveil ancient coloring methods

“…The stock solution of Nafion® 0.5% w/v was prepared by 1:10 dilution with methanol of 5% Nafion® solution. After the micro-particle sampling, the scratched powders were deposited directly at the GCE surface, immobilized by adding 2–3 μL of Nafion® 0.5% solution and let dry at room temperature, as previously reported in 39 . Square wave voltammetry was used as a detection method using the following parameters: potential window from − 1.0 to + 1.0 V, scanned in the negative (cathodic) or positive (anodic) direction; amplitude 0.025 V; frequency 5 Hz; potential step increment 0.004 V.…”

Review—Electrochemical and SERS Sensors for Cultural Heritage Diagnostics and Conservation: Recent Advances and Prospects

“…Indeed, the use of Paraloid B72 as immobilization matrix for VMP presents some drawbacks and limits because Paraloid is a non conductive polymer and the highly porous structure of the film that can lead to the release of part of the particles. An alternative approach was proposed by Moretto et al, 71 based on the use of the ion-conductive ionomer, Nafion® that is a perfluorinated ionomer widely used for modifying electrodes, exploiting its ion-exchanger characteristics to preconcentrate cations, as well as to immobilize different analytes such as enzymes, electrocatalysts, electroactive pollutants, etc. [72][73][74][75][76][77][78][79][80] The voltammetric analysis of Prussian blue (PB) microparticles was performed by mixing the finely grinded pigment powder with the ionomer solution, recasting the mixture onto the surface of a glassy carbon electrode and transferring the coated electrode to an electrochemical cell for voltammetric characterization.…”

“…83 The Nafion-based procedure, which requires a very small amount of the sample (in the order of few μg), has been successfully tested on real samples, namely on Venetian marmorino plaster samples. 71 Another interesting alternative binder suitable to perform VMP has been recently proposed by Abbott et al 84 This study reports on the use of an ionic liquid to immobilize and to keep the electrical contact between the microparticle and the metal surface of the electrode. The ionic liquid used as conducting paste was a deep eutectic solvent (DES) that is a mixture of a quaternary ammonium electrolyte and a hydrogen bond donor, such as urea or ethylene glycol.…”