A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

Abstract

Ion-selective electrodes (ISE) based on conventional plasticized PVC membranes with solid inner contact (SC) have so far had unsatisfactory lower detection limits. Here it is shown that electropolymerization of pyrrole in the presence of potassium hexacyanoferrate(II)/(III) on Pt results in adequate inner contact for SC-ISE. The nanomolar lower detection limit achieved with the Pb 2+ -selective PVC membranes investigated is comparable with values obtained with optimized internal solutions of liquid-contact ISE.

A solid-contact Pb2+-selective electrode using poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) as ion-to-electron transducer

“…For preparation of each solid-contact electrode, 10-20 L of a 50 mg mL −1 MEH-PPV solution in chlorobenzene was applied on the Au disc by drop-casting. After the CP membrane was dry, a piece of PVC tube was put on the tip of the Au disc electrode [1,13]. Finally, 100 L of membrane cocktail was cast on the top of CP surrounded by the PVC tube.…”

“…CPs represent a large family of synthetic metals, however, the commonly studied subjects of SC-ISEs were mostly confined to polypyrrole [13][14][15], polyaniline [16,17], polythiophene, and their derivatives [18][19][20]. From both the experimental and theoretical points of view, it is of great significance to provide new solid contact materials for fabricating SC-ISEs.…”

“…The drawback of this copolymer is that it is currently synthesized in-house. From the practical viewpoint, there is still a great need for the fabrication of SC-ISEs by using commercially available polymer matrixes [13].…”

Electrochemical Sensors

“…24 The authors performed reconditioning steps on their electrodes that helped them eliminate an undesired water layer between membrane and solid contact. The resulting electrodes were virtually free of long-term drifts, suggesting that such water layers, rather than spontaneous discharge reaction of the polymer, may be responsible for long term instabilities.…”

A simple approach for fabricating solid-contact ion-selective electrodes using nanomaterials as transducers

“…Potential instabilities of CWEs have been mainly attributed to the lack of a well-defined redox couple and the formation of a water layer at the membrane-metal interface [7]. The historical problem of poor potential stability between the ion-selective membrane and the conducting wire has been largely solved by the introduction of conducting polymers [8] such as poly(3-octylthiophene) (POT) [9,10], polypyrrole (PPy) [11], polythiophene [12], polyaniline [13], and poly (3,4-ethylenedioxythiophene) [14] as ion-to-electron transducers. Although the ISEs based on these transducing materials show benefits compared to those of traditional ISE with an internal solution, they also suffer from some drawbacks such as sensitivity to light, O 2 , CO 2 , and pH [3].…”