Determination of alpha-naphthol by an oscillating chemical reaction using the analyte pulse perturbation technique

Ultrasensitive self-enhanced electrochemiluminescence sensor based on novel PAN@Ru@PEI@Nafion nanofiber mat

A novel self-enhanced electrochemiluminescence nanofiber mat was for the first time prepared by one-step electrospinning a mixture of polyacrylonitrile, Ru(bpy)₃²⁺, poly(ethylenimine) and Nafion.

Dynamical regime of resorcinol based Belousov–Zhabotinsky chemical oscillator in the presence or absence of some hydrophobic antioxidants in aqueous–organic mixed media

BZ reaction acts as radical generator in AN/DMF mixed solvent system.

The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing

Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

Experimental assessment of the sensitiveness of an electrochemical oscillator towards chemical perturbations

In this study we address the problem of the response of a (electro)chemical oscillator towards chemical perturbations of different magnitudes. The chemical perturbation was achieved by addition of distinct amounts of trifluoromethanesulfonate (TFMSA), a rather stable and non-specifically adsorbing anion, and the system under investigation was the methanol electro-oxidation reaction under both stationary and oscillatory regimes. Increasing the anion concentration resulted in a decrease in the reaction rates of methanol oxidation and a general decrease in the parameter window where oscillations occurred. Furthermore, the addition of TFMSA was found to decrease the induction period and the total duration of oscillations. The mechanism underlying these observations was derived mathematically and revealed that inhibition in the methanol oxidation through blockage of active sites was found to further accelerate the intrinsic non-stationarity of the unperturbed system. Altogether, the presented results are among the few concerning the experimental assessment of the sensitiveness of an oscillator towards chemical perturbations. The universal nature of the complex chemical oscillator investigated here might be used for reference when studying the dynamics of other less accessible perturbed networks of (bio)chemical reactions.

Determination of Alizarin Red S using a novel B-Z oscillation system catalyzed by a tetraazamacrocyclic complex

A new and convenient method for the determination of Alizarin Red S by the perturbations caused by different amounts of Alizarin Red S on a novel B-Z oscillating system is proposed. This new type Belousov-Zhabotinskii involves a macrocyclic copper(II) complex [CuL](ClO4)2 as catalyst and malic acid as the substrate. The ligand L in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. It is found that the relationship between the change in the oscillation amplitude and the logarithm of the Alizarin Red S concentration in the range of 1.5 × 10−7 to 1 × 10−3 M fits a polynomial model: ΔA = 659 + 184.2 log [Alizarin Red S]+ 12.9 log2 [Alizarin Red S]. The RSD obtained with ten samples is 4.4%. The probable mechanism involving the perturbation of Alizarin Red S on the oscillating chemical system is also discussed.