Development of ion-selective electrodes: application in detection system of FIA and strategies for the improvement of detection limit

Author(s)

Karin Yanet Chumbimuni Torres

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2005-09-27

Examining board members

Lauro Tatsuo Kubota; Ivano Gebhardt Rolf Gutz; Yaico dirce Tanimoto de Albuquerque; Jarbas José Rodrigues Rohwedder; José Alberto Fracassi da Silva

• Advisor: Lauro Tatsuo Kubota

Abstract

The present work describes the development of ion-selective electrodes for calcium, potassium, sodium and chloride to be employed in flow injection analyses and its application for the simultaneous determination in samples, as well as, the development of solid contact ionselective electrodes with detection limit in the nanomolar range. The preparation of ion-selective electrodes for calcium, potassium, sodium and chloride was performed optimizing them in steady-state and then incorporated in simultaneous low injection analyses. The optimization of common parameters, such as: pH, buffer, injection volume, flow, etc., was performed looking for the simultaneous determination, using an array of electrodes in series. The proposed potentiometric FIA system was satisfactory for simultaneous determination of these ions in juice samples, and the results, when compared to the reference method, were statistically the same in the 95% of confidence level. In relation to the development of solid contact ion-selective electrodes with low detection limit, four different electrodes were developed for silver, lead, calcium and iodide, with excellent nernstian response and detection limit in the nanomolar range. The obtained detection limits were 2 nmol L for Ag, 1 nmol L for Pb, 4 nmol L for Ca e 10 nmol L for I. It was possible by using the conducting polymer, poly(3-octylthiophene) as an interface between the solid contact and polymeric membrane, methyl metacrylate decyl metacrylate copolymer. The electrodes presented short response time and good repetibility, being potentially useful for determination in trace levels (AU)