摘要 :
The calix[4]-aza-crown derivatives have been used in polymeric ion selective electrodes (ISEs) for pH sensing. The membranes containing ionophores and cation exchangers showed near Nernstian response to hydrogen ions and wide dyna...
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The calix[4]-aza-crown derivatives have been used in polymeric ion selective electrodes (ISEs) for pH sensing. The membranes containing ionophores and cation exchangers showed near Nernstian response to hydrogen ions and wide dynamic range. New carrier based electrodes exhibited high selectivity over alkali metal ions. The binding properties of ionophores with hydrogen ions (acidity constants pK_a) in solvent polymeric membranes were characterized in situ by the so-called sandwich membrane method. The influence of membrane solvents (plasticizers) and the types of the ion exchangers were studied.
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摘要 :
Room temperature ionic liquids (RTILs), based on imidazolium, pyridinium and phosphonium cations, have been studied as an anion-exchanger and plasticizer for poly(vinyl chloride) (PVC)-based potentiometric ion-selective membranes....
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Room temperature ionic liquids (RTILs), based on imidazolium, pyridinium and phosphonium cations, have been studied as an anion-exchanger and plasticizer for poly(vinyl chloride) (PVC)-based potentiometric ion-selective membranes. 1-Methyl-3-octylimidazolium chloride (MOImCl) and trihexyl-tetradecylphosphonium chloride (THTDPC1) can plasticize PVC to form flexible ion-sensing membranes. PVC-MOImCl membrane without additional ionophore and ion-exchanger demonstrated Nernstian response to sulfate ion with slope of 29.1 mV/decade in the concentration range of 10~(-5) to 10~(-1) M. The ionophore-free membrane showed good selectivity toward SO_4~(2-) over Cl~-, ClO_4~-, NO_3~- and SCN~-. PVC-MOImCl-based electrode have fast response time within 10 s and wide pH independent range (3-10). The proposed electrode was used for the determination of sulfate in drinking water samples with satisfactory results. On the other hand, PVC-THTDPCl membrane exhibited stable and Nernstian response to different anions and the selectivity followed the Hofmeister series. Additionally, THTDPCl was found to be a suitable alternative to the traditional anion-exchanger, TDMACl and can be used as ionic additives in ionophore-based ion-selective sensors.
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