ELECTROCHEMICAL DETECTION OF ARSENITE EMPLOYING AND HYDROGEL SOFT MATRIX

RODRIGUEZ, RUSBEL CONEO; BARBERO, CESAR ALFREDO; MARTINEZ, MARIA VICTORIA; ACEVEDO, DIEGO F.; BRUNO, MARIANO M.

Cancún

Congreso; XXVII INTERNATIONAL MATERIALS RESEARCH CONGRES; 2019

Sociedad mexicana de materiales AC- MRS

Polymeric hydrogels are crosslinked polymer networks which are able to retain a significant amount(>80 %) of aqueous solution. Such materials have been used for several technological applications,including contact lenses, diapers, drug delivery, and water retention in agriculture. The hydrogelscapability to sorb specific molecules or ions and retained inside the solid allow to these materials beused in technological applications. This sorption capacity depends on the different interactions(coulombic, hydrophobic, hydrogen bonding, etc) of the chemical species with the polymer matrix.Such specific sorption of chemical species inside the hydrogel is a suitable way for solid phaseextraction of chemical reagents aqueous solutions.In this work the hydrogel soft matrix is tested as selective sorbent and as a platform to perform theelectrochemical detection of redox analite. The method proposes that the hydrogel can be load by theanalite by immersing in the aqueous matrix sample. After that, the matrix is extracted the sampleand the electrochemistry is performed in immobilized solution inside of the gel. In this work,poly(N-isopropylacrylamde) bearing cationic groups (PNIPMA-co-50%APTMAC) was used to preloadedarsenite ions. The method consists in place a preloaded hydrogel with arsenite into theelectrochemistry cell and presses the working electrode onto the gel until reaching a good contactfilling the cell with electrolyte. The studied hydrogels are able to swell in aqueous media at pH 9.6(Sweq>1500), where the electrochemstry measures were made. The electrochemistry detection ofarsenite in all studied sample was carry out by cyclic voltammetry employing a cobalt oxide filmmodified GC electrode. It is found that the oxidation peak current (Ip) employing a cationic hydrogelis almost eight times higher than the current peak in PNIPAM hydrogel (neutral polymer) indicating astrong electrostatic interaction between cationic group and arsenite anion. Complexes matrix as tapwater samples communities in Argentina were also analyzed by this method, showing comparableresults to those measured by atomic absorption Spectroscopy. These results would suggest that themethod proposed can to detect arsenite in real samples, make it suitable on-field analysis.