All solid state chronopotentiometric ion-selective electrodes based on ferrocene functionalized PVC

• An all solid contact ion-selective electrode based on poly(vinyl chloride) covalently modified with ferrocene moieties allows one to operate the membrane in a chronopotentiometric sensing mode. The membrane is considered as initially non-perm-selective towards anions, and an applied anodic current provokes a defined anion flux in direction of the membrane. With this protocol, a variety of anions can be depleted at the membrane surface. Since this model system does not yet contain an ionophore, their order of preference follows the expected Hofmeister selectivity sequence. The all solid-state configuration tolerates an imposed current density of 1.4 μA mm−2, which translates into an upper detection limit of ca. 1.2 mM. Higher current densities of up to 31.2 μA mm−2are possible with addition of freely dissolved alkyl ferrocene derivative for an expected upper detection limit of 17.0 mM. Numerical simulations are performed in order to establish the fundamental basis of the mechanism that takes place in this all solid-state membrane electrode. The oxidation of bound Fc and the ion-transfer process are considered in the simulation. In view of developing an analytical sensor, different anions are tested. A linear range of two orders of magnitude from 0.01 to 1 mM is found. The membranes are evaluated over several days, displaying practically the same slopes and intercepts, with a RSD of less than 2%. Electrochemical limitations of free Fc and bound Fc are critical evaluated. This approach should allow one to develop a new family of solid-state chronopotentiometric ion sensors that require relatively high current densities.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

Chronopotentiometry; Ferrocene; Ion-selective membranes; Permselective membranes; Solid contact transducer

Publication and Content Type

ref (subject category)

art (subject category)