Electrochemical solid-phase microextraction of anions and cations using polypyrrole coatings and an integrated three-electrode device

Abstract

A method for the extraction, transfer and desorption of anions and cations under controlled potential conditions employing a new integrated three-electrode device is described. The device, containing working, reference and counter electrodes, was prepared from tubes that could be moved vertically with respect to each other. In this way, a small amount of solvent, held by capillary force, remained between the electrodes when the device was lifted out of a solution after an extraction. This design allowed the potential control to be maintained at all times. With the new integrated device, it was possible to perform potential controlled desorption into vials containing as little as 200 microl of solution. The required ion exchange capacity was obtained by electrodeposition of a polypyrrole coating on the surface of the glassy carbon working electrode. Solid-phase microextractions of several cations or anions were performed simultaneously under potentiostatic control by doping the polypyrrole coating with different anions such as perchlorate and p-toluenesulfonate. The efficiency of the extractions, which could be altered by varying the potential of the working electrode, could be increased by 150 to 200% compared to extractions using normal solid-phase microextraction conditions under open circuit conditions. A constant potential of +1.0 V and -0.5 V with respect to the silver pseudo reference electrode, was found to be well-suited for the extraction of samples containing ppm concentrations of anions (chloride, nitrite, bromide, nitrate, sulfate and phosphate) and cations (cadmium, cobalt and zinc), respectively.

Dye-doped Nanostructure Polypyrrole Film for Electrochemically Switching Solid-phase Microextraction of Ni(II) and ICP-OES Analysis of Waste Water

“…14,15 Polypyrrole and its derivatives have attracted great interest in the development of electrochemically switched solid-phase microextraction (ES-SPME) as ion-exchange material for charged species. [16][17][18] The main advantage of using conducting polymers in SPME is that the charge of the coatings can be readily controlled by the oxidation and reduction of the polymers. PPy with small counter-ions, e.g., Cl -, ClO4 -and NO3 -, mainly exhibits an anion exchanger behavior due to the high mobility of these ions in the polymer matrix.…”

Electrochemically controlled in-tube solid phase microextraction

“…Anion extraction and desorption has occurred. EC-SPME has been successfully used in the extraction of anionic [28][29][30][31], cationic [32], neutral [33], and both cationic and anionic [34] analytes. For instance, Liljegren and Nyholm used PPy coated microarray electrodes for electrochemically controlled solid-phase microextraction and preconcentration on individually addressable gold microband electrodes.…”

Composite films of poly-(ester-sulphonated) and poly-(3-methylthiophene) for ion-exchange voltammetry in acetonitrile solutions

“…To this aim, two main approaches were followed: one based on the use of electroactive films with electrochemically controllable ion-exchange properties such as redox polymers [2][3][4][5] or conducting polymers [6,7], the other taking advantage of the special properties of composite films in which the (switchable) anionexchange properties of oxidized conducting polymers were compensated and combined with the cation-exchange properties of polyelectrolytes [8][9][10][11][12][13][14][15][16][17]. Very recently, these studies brought to the proposal of using electrochemically controlled films for performing and controlling electrochemically the solid phase micro extraction (SPME) of anions or cations [9,15,18,19].…”