Strom-Spannungs-Messungen an der BaSO4-cellophan-Membran

Analytical Study of an Iodide-Sensitive Membrane Electrode.

“…Recently, Hirsch-Ayalon (3) used current-voltage measurements to study the permeation of ions through BaS04-cellophane membranes; the results obtained are in qualitative agreement with observed selectivity trends of such electrodes. The present authors favor the phaseboundary model of electrode response, in analogy with the mode of operation of glass membrane electrodes (10), but it is clear that a great deal more experimental work is necessary before a definitive mechanism can be proposed.…”

Precipitation membranes: III. Reversible changes of membrane properties induced by alterations in ionic concentrations

“…On the other hand, in the "conditioning experiments" the minimum concentrations necessary to make a conditioned BaSO4 membrane from a new sheet of cellophane were 1.5 x 10-4M for both reagents, thus three times as high as the value of C1im found here. The development of a new conditioned BaSO~ membrane is not simply the reversal of deconditioning, but a complicated cooperative process in which supersaturations, nucleation, and precipitation participate in a statistical manner [5].…”

“…Counter diffusion of calcium hydroxide vs. oxalic acid or vs. phosphate, barium hydroxide vs. sulfuric acid, as well as many other combinations, produce precipitation membranes (PM) [3]. They act as ion selective barriers and display rectification of electrical currents when they are in the "conditioned state" [5,6].In order to obtain a PM in the conditioned state, the two ions of opposite signs which form the precipitate must be present in the respective adjoining solutions.The membrane is easily "deconditioned" and "reconditioned", e.g., its special properties disappear and are restored, respectively. Deconditioning can be effected in two ways: (i) by removing one (or both) of the generating ions from the adjoining solutions, or (ii) by applying…”

Precipitation membrane effects in biologic membranes: The role of calcium

“…This behavior is analogous to chemical deconditioning of precipitation membranes. Our findings support the assumption that the binding of calcium in biologic membranes produces electrical effects characteristic of precipitation membranes.Rectification of electrical current has frequently been observed during the study of the current-voltage (I,A 9g) relations in biologic membranes.Precipitation membranes display rectification, as well as other properties, similar to those of biologic membranes (Hirsch-Ayalon, 1965; KatzirKatchalsky, Hirsch-Ayalon & Michaeli, 1973). In this study we show that electrical rectification in the frog skin depends on the presence of calcium and reversibly disappears upon its removal from the external bathing solution.…”