A comparative study of chromium(III) ion-selective electrodes based on N,N-bis(salicylidene)-o-phenylenediaminatechromium(III)

Abstract

A comparative study was made between three types of Cr(III) ion-selective electrodes: PVC membrane electrode, silver coated electrode and modified carbon paste electrode based on N,N-bis(salicylidene)-o-phenylenediaminatechromium(III) complex (Crsalophen). As anticipated, electrodes with a solid contact, rather than a traditional liquid inner contact, give lower detection limits because of diminished ion fluxes. Often, however, ill-defined solid contact gives rise to instabilities and interferences by oxygen gas. The carbon paste electrode provides a more sensitive and stable device than that afforded by PVC and coated electrodes. The best performance was obtained by an electrode based on the paste containing 3.5 wt% Cr-complex, 48.5% graphite plasticized with a mixture of 24.0 wt% tris(2-ethylhexyl) phosphate (DOPh) + 24.0 wt% dioctyl sebacate (DOS). The sensor has a linear dynamic range of 7.5 × 10 -6 to 1.0 × 10 -2 M, with a Nernstian slope of 20.1 ± 0.6 mV decade -1 , and a detection limit of 1.8 × 10 -6 . It has a short response time of a bout 8 s and is applicable in a pH range of 4.5-7.7. It was successfully used as an indicator electrode in potentiometric titration of Cr(III) with EDTA and in determination of Cr(III) in water samples and chromium in (Crsalophen).

Selective determination of Cr(III) by modified carbon nanotube paste electrode: a potentiometric study

“…Other studies have reported a wide optimum working pH range of 2.0–9.0, 9 4.5–8.0, 23 and 1.7–6.5 24 for recently introduced Cr(III) ion‐selective sensors. Considering the chemistry of trivalent chromium and the chemical species of Cr(III) at different pHs, a pH range of 4.0–6.5 was selected as the optimum working pH of the electrode.…”

“…Additionally, the variation of the electrode response at basic solutions may be due to metal ions hydrolysis and the formation of soluble/insoluble hydroxyl complexes. 12 Other studies have reported a wide optimum working pH range of 2.0-9.0, 9 4.5-8.0, 23 and 1.7-6.5 24 for recently introduced Cr(III) ionselective sensors. Considering the chemistry of trivalent chromium and the chemical species of Cr(III) at different pHs, a pH range of 4.0-6.5 was selected as the optimum working pH of the electrode.…”

A new potentiometric sensor for the determination of ketamine hydrochloride in ampoules and urine

“…In addition, they should have good solubility in the paste matrix and sufficient lipophilicity to prevent leaching from the paste into the sample solution. 45 The ion-exchangers KT-ST, KT-SM, KT-PT, KT-PM and KT-TPB were prepared and tested as modiers for the present electrode. The inuence of the amount of the different ketamine ion-exchangers in the carbon paste was investigated, and the corresponding results are summarized in Table 1.…”

A New Potentiometric Sensor for Determination of Pethidine hydrochloride in Ampoules and Urine

“…Ion-exchanger complex used in ISEs should have rapid exchange kinetics and adequate formation constants in the paste. In addition, they should have good solubility in the paste matrix and sufficient lipophilicity to prevent leaching from the paste into the sample solution [22,23].…”