Application of Pyrite and Chalcopyrite Electrodes for the Acid-Base Determinations in Nitriles

Abstract

Os minerais naturais pirita e chalcopirita tem sido usados como sensores em eletrodos indicadores usando acetronitrila e propionitrila como solventes. Os resultados mostram vantagens excepcionais da pirita e chacopirita como sensores eletroquímicos e também a possibilidade de aplicação desses eletrodos para determinações em solventes não aquosos onde eletrodos de vidro mostram dificuldades. O comportamento dos eletrodos indicadores de pirita e chalcopirita em nitrila foi avaliado pela titulação de diversas bases e ácidos de forças diferentes usando prótons e íons liato gerados pela oxidação de alguns ésteres de ácido gálico e fenóis diidróxi, bem como m-cresol e 3-metóxifenol. Os resultados obtidos com esses eletrodos foram comparados com os de eletrodos de vidro nas mesmas condições, obtendo-se boa concordância, reprodutividade e precisão. Os desvios padrão na determinação dos ácidos e bases investigados foram menores do que 0,9%. Em titulações potenciométricas com pirita e chalcopirita como eletrodos indicadores, o potencial é instantaneamente estabelecido. Ambos os eletrodos podem ser usados sem qualquer limitação temporal ou divergências potenciais consideráveis.The natural minerals pyrite and chalcopyrite have been used as the indicator electrode sensors using acetonitrile and propionitrile as solvents. The results show the exceptional advantage of pyrite and chalcopyrite as electrochemical sensors and also the possibility of the application of these electrodes for the determination in nonaqueous solutions where glass electrode shows many defaults. The behaviour of the pyrite and chalcopyrite indicator electrodes in nitriles were checked by titrating several bases and acids of different strengths using protons and lyate ions generated by the oxidation of some gallic acid esters and dihydroxy phenols, as well as m-cresol and 3-metoxy phenol. The results obtained by using these electrodes were compared with those obtained by the application of a glass electrode under the same conditions, and good agreement, reproducibility and accuracy were obtained. The standard deviation of the determination of the investigated acids and bases was less than 0.9%. In the potentiometric titrations with pyrite and chalcopyrite indicator electrodes, the potential is instantaneously established throughout. Both electrodes can be used without any time limit or without considerable divergence in potentials.

Application of pyrite and chalcopyrite as sensor electrode for amperometric detection and measurement of hydrogen peroxide

“…Due to their excellent characteristics such as semiconductivity, non-toxicity, and availability in the nature pyrite and chalcopyrite have recently been used in various electrochemical applications in the form of solid state sensor materials. [33][34][35][36] In this study, the natural minerals (pyrite and chalcopyrite) were used as the working electrode to detect the H 2 O 2 in aqueous solution. The main purpose of this study was to further explore analytical applications of pyrite and chalcopyrite electrodes, with a focus on developing an inexpensive, rapid and convenient method for the determination of biologically important compound, H 2 O 2 .…”

“…Due to their excellent characteristics such as semiconductivity, non-toxicity, and availability in the nature pyrite and chalcopyrite have recently been used in various electrochemical applications in the form of solid state sensor materials. 33–36 …”

A new fluorescent pH probe for acidic conditions

“…Melting points were detected on an XD-4 digital micro melting point apparatus. 1 H NMR spectra were recorded on a Bruker Avance 400 (400 MHz) spectrometer and 13 C NMR spectra were recorded on a Bruker Avance 300 (75 MHz) spectrometer, using DMSO-d 6 as solvent and tetramethylsilane (TMS) as an internal standard. HRMS spectra were recorded on a Q-TOF6510 spectrograph (Agilent).…”

“…The general synthetic route of the probe was shown in Scheme 1. The structure of the probe was characterized by 1 H NMR, 13 C NMR and HRMS spectra, especially, by X-ray single crystal diffraction.…”

“…It is reported that many detection methods including acidbase indicator titration 13 and potentiometric titration 14 have been used to measure pH value. But these detection methods are expensive, easily interfered by metal ions and complex environment.…”