A. V. Kopytin

Ion-selective sensors for determining Au(CN) 2 − with membranes based on the ionic liquid tetradecylphosphonium dicyanoaurate

A polymeric membrane for an ion-selective electrode is proposed on the basis of supramolecular systems including a polymeric compound (polyvinyl chloride, PVC) and an ionophore (ionic liquid tetradecylphosphonium dicyanoaurate) in which ionic liquid is simultaneously used as a PVC plasticizer. The selectivity, linear response range, and potential stability of ion-selective electrodes with the optimum membrane composition are measured. The detection limit for Au(I) with the developed electrode is 4.5 × 10−7 M.

Potentiometric sensors with membranes based on ionic liquid tetradecylammonium triethylammonio-closo-dodecaborate

Polymer compositions based on the ionic liquid tetradecylammonium triethylammonium-closododecaborate (TTCD) are proposed as the main components of membranes of potentiometric sensors (ion-selective electrodes) for determining ions [B12H11N(C2H5)3]−. Two types of polymer compositions are considered: conventional, polyvinyl chloride (PVC)-liquid ion-exchanger (solution of TTCD in o-nitrophenyl octyl ether) and another, PVC-TTCD (ionophore-plasticizer). The optimal composition of membranes for both types of electrodes are proposed, and their main electroanalytical parameters, such as selectivity, effect of pH, range of linear response, reproducibility, and stability of potential, were measured. A comparative analysis of the electroanalytical parameters of potentiometric sensors with membranes of two types is given. The detection limits for the electrodes of types I and II are 9 × 10−7 and 4 × 10−7 M. It is shown that [B12H11N(C2H5)3]− anions can be determined by potentiometric titration with indicator electrodes of different types.

Ion-selective electrodes for the determination of closoborate anions

Ion-selective electrodes are proposed on the basis of tetradecylammonium salts for determining [B12H12]2−, [B10H10]2−, and [B10Cl10]2−closoborate anions. Their basic electroanalytical parameters, selectivity, linear response range, detection limit, potential stability, and the pH effect on electrode indications are estimated. The closoborate anions can be arranged in the following series by the selectivity of their determination: [B10Cl10]2− ≫ [B12H12]2− > [B10H10]2−.

Ion-selective electrode for the determination of dimethylbenzylammonium ions

A sensor is proposed for the direct potentiometric determination of dimethylbenzylammonium in acid and neutral aqueous solutions. The sensor membrane is made of a polymeric composition on the basis of polyvinylchloride containing an ion associate and a solvent as a plasticizer. Salts of the tetraphenylborate anion and its derivatives served as ionophores. Basic electroanalytical parameters of the developed potentiometric sensors are studied and the pH range of their possible application is determined. The developed sensor is used as a reference electrode in the potentiometric titration of dimethylbenzylammonium with tetraphenylborate anions.

An ion-selective potentiometric sensor for hexafluoroarsenate

Ion-selective potentiometric sensors (ion selective electrodes, ISEs) based on tetradecylphosphonium hexafluoroarsenate are developed for the determination of AsF6− ions. Their main parameters, such as selectivity, linearity range of response, detection limit, and also the effect of pH on the readings of electrodes are evaluated. The developed electrode demonstrated high selectivity to the AsF6− acido-complex in the presence of various anions. The detection limit goes up with increasing concentration of HF; for fluoridefree neat solutions of LiAsF6, it is 3 × 10−7, pAsF6 = 6.52; at the concentrations of HF 0.1 and 4 M, it is 1.5 × 10−6 M, pAsF6 = 5.82, and 7 × 10−6 M, pAsF6 = 5.15, respectively.

Phosphororganic tripodand ionophores as chemical sensor components of the PVC membrane ISEs

A new powerful complexing group of phosphororganic tripodandes (POTP) synthesized by an economic approach were studied as chemical sensors for different ionoselective electrodes. The substitutive central group of POTP influenced the characteristic rows of the potentiometric selectivity coefficient. The central-phosphoric tripodandes were highly selective to Ca/sup 2+/ and Pb/sup 2+/, while the central-amine tripodandes were selective to Cd/sup 2+/, Pb/sup 2+/ and Cs/sup +/. The selectivity of the central-amine tripodandes strongly depended on the substituting of the N-adjusted methylene group for the ethyleneglycol group. For membranes sensorized with the central-phosphorous podandes, the enlargement of the by-side chain for one methylene group made no practical influence on the selectivity characteristics.

Synthesis and properties of podands with 4-antipyryliminomethine groups

Novel podands with 4-antipyryliminomethine groups on benzenes and various numbers of ethers are prepared. According to UV spectroscopy, these compounds form complexes with alkali, alkaline earth, and transition metals. Extraction of metal picrates demonstrated that the podands selectively form extractable complexes with these salts. A lead-selective electrode with an electrode function 22–24 mV/pPb is based on 1,8-bis[2-(4-antipyryliminomethine)phenoxy]-3,6-dioxaoctane. This enables 1·10−6−1·10−2 M Pb to be determined in the pH range 3.5–5.5. The electrode is highly selective for Pb in the presence of alkali and alkaline earth metals.