Amperometric Ion Sensing Using Polypyrrole Membranes

Abstract

Oxidation/reduction of conducting polymers, coupled with ion exchange between the polymer and electrolyte solution can be utilized for amperometric ion sensing. Electrochemically deposited ™model∫ polypyrrole membranes doped by chloride (PPyCl) and hexacyanoferrate (PPyFeCN) anions were studied from the point of view of their advantages and limits for amperometric determination of electroinactive anions and cations, respectively. Monotonous dependences of the current on electrolyte concentration were obtained for short reading times after potential step application (in the range of ms). The experimental conditions were optimized to obtain linear dependences: log (current) vs. log (KCl concentration) within the range 10 À6 À 1 M. The advantages of the amperometric method over the potentiometric one are highlighted: much lower effect of redox and pH interferences, wider concentration range, elimination of long conditioning procedure.

Sensitivity and Selectivity of Polypyrrole Based AC‐Amperometric Sensors for Electroinactive Ions – Frequency and Applied Potential Influence

“…A nontypical behavior is observed for K 2 SO 4 and especially KSCN, with AC-current decreasing for high (Fig. 4B), where polypyrrole is only partly oxidized, the ratio of currents corresponding to NO À 3 and Cl À is now close to 4, for concentration 0.1 M. This difference is greater than obtained under pulse amperometry conditions [17]. The highest current value recorded for NO À 3 ions can be ascribed to the influence of ion -polymer interactions.…”

“…By changing the time-scale of the measurement, the desired response can be exposed. Under pulse amperometry conditions, with increasing pulse duration time the selectivity slightly increases at the expense of sensitivity [17]. The accessible ion concentration range is comparable with that usually achieved under potentiometric conditions.…”

“…Despite the higher cost of apparatus in comparison to potentiometry, using unmodified conducting polymer membranes, amperometric methods seem more flexible from the point of view of selectivity and sensitivity enhancement and tailoring. It was shown that analytical amperometric characteristic of conducting polymer membranes could be easily modified by applied potential and current sampling mode [17,18]. By changing the time-scale of the measurement, the desired response can be exposed.…”

Conducting polymers in chemical sensors and arrays

“…Voltammetric and amperometric transducers based on CP are used for detection of current caused by either electrocatalysis or by ion flux into/from CP during its oxidation/reduction [268]. The both processes are poor selective, therefore their typical application is an amperometric detection in chromatography [244,[269][270][271].…”

Disposable Electrospun Electrodes Based on Conducting Nanofibers

“…Firstly, conducting polymers are versatile since they can be used alone [2] or in combination with chemical [3] or biological [4] components embedded in their polymeric structure [5]. Secondly, conducting polymers can be easily modeled towards one-dimensional (1-D) nanoscale morphology [6].…”