Cecylia Wardak

A highly selective lead-sensitive electrode with solid contact based on ionic liquid

A new polyvinylchloride membrane sensor for Pb(2+) with solid contact based on ionic liquid has been prepared. The electrode shows a Nernstian response for lead ions over a wide concentration range (1×10(-8) to 1×10(-1) mol L(-1)) and the slope of 29.8 mV/decade. The limit of detection is 4.3×10(-9) mol L(-1). It has a fast response time of 5-7 s and can be used for 4 months without any divergence in potential. The proposed sensor is not pH sensitive in the range 3.5-7.3 and shows a very good discriminating ability towards Pb(2+) ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied as an indicator electrode in potentiometric titration of lead ions with K(2)CrO(4) and for direct determination of Pb(2+) ions in real sample solution.

Properties of ion-selective electrodes with polymer membranes for ibuprofen determination☆

Abstract Composition of a polymeric potential-determining phase for the ibuprofen selective electrode was determined. The different possibilities of using various quaternary ammonium salts — dimethyldidecylammonium bromide, methyltrioctylammonium chloride, tetraoctylammonium chloride and methyltrioctyloammonium 2-(4-isobuthylphenyl) priopionate—as anion exchangers in polymer membranes of ibuprofen electrodes were examined. The following basic electrode parameters were investigated: measurement range, slope, limit of detection, lifetime, dependence of the electrode potential on pH and selectivity coefficients in relation to some organic and inorganic anions.

A new voltammetric strategy for sensitive and selective determination of gallium using cupferron as a complexing agent

This article describes a differential pulse adsorptive stripping voltammetric method for the trace determination of gallium in environmental water samples. It is based on the adsorptive deposition of the complex Ga(III)-cupferron at the hanging mercury drop electrode (HMDE) at −0.4 V (versus Ag/AgCl) and its cathodic stripping during the potential scan. The method was optimized as concerns the main electrochemical parameters that affect the voltammetric determination (supporting electrolyte, pH, cupferron concentration, deposition potential and time). The calibration graph is linear from 5 × 10−10 to 5 × 10−7 mol L−1 with a detection limit calculated as 1.3 × 10−10 mol L−1 for deposition time of 30 s. The influence of interfering substances such as surfactants and humic substances present in the matrices of natural water samples on the Ga(III) signal was examined and a satisfying minimization of these interferences was proposed. The procedure was applied to direct determination of gallium in environmental water samples.

Ionic liquids as new lipophilic additives to the membrane of lead ion-selective electrodes with solid contact

The potentiometric properties of lead-selective electrodes with solid contact containing in the polymeric membrane addition of ionic liquids (ILs) were investigated. The studies were carried out with plasticised PVC membranes doped with alkylmethyl imidazolium chlorides. The electrode basic analytical parameters, such as detection limit, linear range, slope characteristic, response time and dependence of the electrode potential on pH as well as selectivity coefficients in relation to some inorganic cations were determined. As follows from the studies, the addition of ILs to the membrane phase improved the analytical parameters of the studied electrodes, especially the improvement in selectivity was notable. The best results were obtained for electrode having membrane dopped with 1-butyl-3-methylimidazolium chloride (BMImCl).

Properties of naproxen ion-selective electrodes

Naproxen membrane electrodes based on different plasticizers and the quaternary ammonium salts (QASs) dimethyldidecylammonium bromide, methyltrioctylammonium chloride, or tetraoctylammonium chloride, were prepared. The following basic parameters were investigated for the optimal electrode: measurement range (10−4 − 10−1 mol L−1), slope of the linear range of the calibration curve (−58.3 mV decade−1), limit of detection (6.0 × 10−5 mol L−1), lifetime (2.5 months), dependence of the electrode potential on pH (5.5 − 9.0), reproducibility of potential (1.2 mV) and selectivity coefficients in relation to selected organic and inorganic anions. The electrode was utilized for determination of naproxen in tablets by the calibration curve method and the standard addition method.

Solid contact Zn2+ -selective electrode with low detection limit and stable and reversible potential

AbstractA new solid contact Zn2+ polyvinylchloride membrane sensor with 2-(2-Hydroxy-1-naphthylazo)-1,3,4 -thiadiazole as an ionophore has been prepared. For the electrode construction, ionic liquids, alkylmethylimidazolium chlorides are used as transducer media and as a lipophilic ionic membrane component. The addition of ionic liquid to the membrane phase was found to reduce membrane resistance and determine the potential of an internal reference Ag/AgCl electrode. The electrode with the membrane composition: ionophore: PVC: o-NPOE: ionic liquid in the percentage ratio of (wt.) 1:30:66:3, respectively, exhibited the best performance, having a slope of 29.8 mV decade−1 in the concentration range 3×10−7–1×10−1 M. The detection limit is 6.9×10−8 M. It has a fast response time of 5–7 s and exhibits stable and reproducible potential. It has a fast response time of 5–7 s and exhibits stable and reproducible potential, which does not depend on pH in the range 3.8–8.0. The proposed sensor shows a good and satisfactory selectivity towards Zn2+ ion in comparison with other cations including alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for direct determination of zinc ions in tap water and as an indicator electrode in potentiometric titration of Zn2+ ions with EDTA.

Properties of ibuprofen ion-selective electrodes based on the ion pair complex of tetraoctylammonium cation

Ibuprofen membrane electrodes based on different plasticizers: diisobutyl phthalate (DIBP), o-nitrophenyloctyl ether (o-NPOE), dioctyl sebacate (DOS) and tetraoctylammonium 2-(4-isobutylphenyl)propionate were prepared. All electrodes show: a near Nernstian slope of characteristic (58.3–60.9 mV decade−1) in the measurement range (10−4–10−1 mol L−1), limit of detection (5.0×10−5 mol L−1), really long lifetime (12 months), dependence of the electrode potential on pH (5.5–9.0), reproducibility of potential (0.6–1.2 mV) and selectivity coefficients in relation to some organic and inorganic anions. The electrodes were applied for the determination of ibuprofen in tablets by the calibration curve method and the standard addition method.

1-Hexyl-3-methylimidazolium hexafluorophosphate as new component of polymeric membrane of lead ion-selective electrode

abstract The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate is used as a new lipophilic ionic additive in the polymeric membrane of a solid contact type lead ion-selective electrode. The membrane is deposited on an internal glassy carbon electrode with poly(3-octyl)thiophene as an intermediate layer. The sensor exhibits good analytical parameters: low detection limit of 3.5 × 10−9 mol L−1, Nernstian response slope of 29.8 mV/decade, a wide concentration range of 1 × 10−8−1 × 10−1 mol L−1, short response time of 7 s, and relatively long lifetime of 100 days. The proposed sensor has a working pH range of 4.0–6.9 and excellent selectivity for Pb(II) ions over a wide variety of other metal ions. The efficiency of the proposed sensor was demonstrated by its application for direct determination of Pb2+ ions in real water samples.

Cobalt(II) ion-selective electrode with solid contact

A new all plastic sensor for Co2+ ions based on 2-amino-5 (hydroxynaphtyloazo-1′)-1,3,4 thiadiazole (ATIDAN) as ionophore was prepared. The electrode exhibits a low detection limit of 1.5 × 10−6 mol L−1 and almost theoretical Nernstian slope in the activity range 4.0 × 10−6–1 × 10−1 mol L−1 of cobalt ions. The response time of the sensor is less than 10 s and it can be used over a period of 6 months without any measurable divergence in potential. The proposed sensor shows a fairly good selectivity for Co(II) over other metal ions. The electrode was successfully applied for determination of Co2+ in real samples and as an indicator electrode in potentiometric titration of Co2+ ions with EDTA.

Studies on Influence of (2-Hydroxypropyl)-

This paper examined the preparation of indomethacin membrane sensors and the effect of β-cyclodextrin on electrode characteristic, selectivity, and response time. Several plasticized poly(vinyl)chloride membranes of different composition were tested and the best electrode based on tetraoctylammonium 1-( p-chlorobenzoyl) 5-methoxy-2-methyl-3-indolylacetate with membrane plasticized with diisobutylphthalate was selected. The electrode shows the sensitivity near Nernstian (-58.7 mV decade^-1) over the linear range of 5×10^-6-1×10^-2 molL^-1 and limit of detection 2.5×10^-6 molL^-1. The present electrode exhibits clear discrimination of indomethacin ions from several inorganic, organic, and some common drug excipients. This electrode has a response time of 9 s and can be used in the pH range 5.5-10 in the period of time 2.5 months without any considerable deterioration. The notably property and attractive quality of the indomethacin sensor are high sensitivity, selectivity, low cost, and comfortable application in drugs analysis. Furthermore, it can be used even in the presence of β-cyclodextrin at a concentration below 1×10^-2 molL^-1.