Ion-Selective Electrodes of Extended Linear Range

Solid-contact ion-selective electrodes with carbazole-derived ionophores were prepared. They were characterized as acetate sensors, but can be used to determine a number of carboxylates. The potentiometric response characteristics (slope, detection limit, selectivity, and pH sensitivity) of sensors prepared with different membrane compositions (ionophore, ionophore concentration, anion exchanger concentration, and plasticizer) were evaluated. The results show that for the macrocyclic ionophores, a larger cavity provided better selectivity. The sensors exhibited modest selectivity for acetate but good selectivity for benzoate. The carbazole-derived ionophores effectively decreased the interference from lipophilic anions, such as bromide, nitrate, iodide, and thiocyanate. The selectivity, detection limit, and linear range were improved by choosing a suitable plasticizer and by reducing the ionophore and anion exchanger concentrations. The influence of the electrode body’s material upon the composition of the plasticized poly(vinyl chloride) membrane, and thus also upon the sensor characteristics, was also studied. The choice of materials for the electrode body significantly affected the characteristics of the sensors.

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The New Ion-Selective Electrodes Developed for Ferric Cations Determination, Modified with Synthesized Al and Fe−Based Nanoparticles

Sensors ◽

10.3390/s22010297 ◽

2021 ◽

Vol 22 (1) ◽

pp. 297

Author(s):

Andrea Paut ◽

Ante Prkić ◽

Ivana Mitar ◽

Lucija Guć ◽

Marijan Marciuš ◽

...

Keyword(s):

Correlation Factor ◽

Linear Range ◽

Ion Selective Electrodes ◽

Al2o3 Nanoparticles ◽

Membrane Composition ◽

X Ray Diffraction ◽

X Ray ◽

Magnetite Fe3o4 ◽

Positive Effect

The solid-state ion-selective electrodes presented here are based on the FePO4:Ag2S:polytetrafluoroethylene (PTFE) = 1:1:2 with an addition of (0.25–1)% microwave-synthesized hematite (α-Fe2O3), magnetite (Fe3O4), boehmite [γ-AlO(OH)], and alumina (Al2O3) nanoparticles (NPs) in order to establish ideal membrane composition for iron(III) cations determination. Synthesized NPs are characterized with Fourier-Transform Infrared (FTIR) spectroscopy, Powder X-Ray Diffraction (PXRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The iron oxides NPs, more specifically, magnetite and hematite, showed a more positive effect on the sensing properties than boehmite and alumina NPs. The hematite NPs had the most significant effect on the linear range for the determination of ferric cations. The membrane containing 0.25% hematite NPs showed a slope of −19.75 mV per decade in the linear range from 1.2∙10−6 to 10−2 mol L−1, with a correlation factor of 0.9925. The recoveries for the determination of ferric cations in standard solutions were 99.4, 106.7, 93.6, and 101.1% for different concentrations.

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