Potentiometric Anion Selective Sensors

Abstract

In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the aqueous solution, and the receptor molecule that introduces the selectivity. This review deals with potentiometric transduction elements that convert membrane potentials into a signal. The structure and properties of membrane materials is discussed. The nature of the anion receptor ultimately determines the selectivity. Both coordination chemistry and hydrogen bonding have been used to design anion receptor molecules. The integration of all three elements by covalent linkage of all elements in durable sensorsystem concludes the review.

Sulfonated poly(ether ether ketone), an ion conducting polymer, as alternative polymeric membrane for the construction of anion-selective electrodes

“…ISEs offer some advantages in comparison to other detection methods such as simplicity, ease of preparation, relatively fast response, selectivity, wide linear dynamic range and low cost [2]. ISEs based on polymeric membranes containing neutral or charged carriers (ionophores) are one of the most successful electrochemical sensors in routine use today [3,4], and they can be used to determine the concentration of a plethora of substances.…”

Anion Sensors

“…In these membranes, the selectivity of the receptor "overrides" the bias toward hydrophobic anionic species, resulting in a more selective system capable of detecting hydrophilic anions. Known as anti-Hofmeister biasing, this technique has resulted in a variety of new ion-selective electrodes for a wide variety of anionic species [5,6]. The membranes used in these systems may also contain positively charged additives such as alkylammonium cations to aid extraction of the anionic species from the aqueous environment into the lipophilic interior of the membrane.…”

“…H NMR (in DMSOd6 ) and fluorescence (acetonitrile) titration experiments. In particular, the MLCT fluorescence band of the macrocycle Proposed binding mechanism of chemosensor 45with PPi.…”

Construction of an anion-selective electrode: Dichromate-selective electrode

“…Despite these characteristics, anion complexation and the design of anion-selective ionophores are far less developed than cationselective ionophores because there are some inherent differences between anions and cations [1]: anions are larger than cations, so they require ionophores with a much larger binding site; anions have many different shapes; anions are more strongly hydrated than cations of the same size while their solvation by organic solvents is generally more difficult; several anions are present only in a narrow pH range, such as dichromate anion.…”