Solid-State Lead-Selective Electrodes- a New Insight into Measurements of Ions at Low Analyte Concentrations

Abstract

In environmental analysis of ions, ion-selective electrodes (ISEs) are frequently investigated as candidates to improve already existing techniques. Potentiometric sensors have several advantages over other analytical techniques, e.g. portability, low energy consumption, and small size. This creates an opportunity to perform analysis at overall lower cost [1, 2]. Despite obvious advantages, ISEs due to the need of re-calibration and fouling are not yet implemented in environmental analysis of ions on an industrial scale [3, 4]. Vast majority or scientific reports dealing with measurements of ions in diluted samples are devoted to solid-contact and conventional (with inner filling solution) ISEs, however, the concept of lowering the detection limit was firstly introduced and studied with solid-state ISEs [5-8].In this study solid-state membrane electrodes were re-vitalized in measurements of ions at low analyte concentration in environmental samples. We used lead(II)-selective electrodes with PbS/Ag2S membranes to develop two methods lowering of the detection limit based on the concentration time-dependent adsorption of the primary ion on the surface of the membrane [9] and tuned galvanostatic polarization (chronopotentiometry) [10]. Furthermore, solid-state electrodes were used to determine lead concentration in environmental sample. Tuned galvanostatic polarization method was found suitable in measurement of lead(II) in environmental samples collected nearby industrially exposed terrain [11]. The chronopotentiometric determination was compared to the analysis done with inductively coupled plasma mass spectrometry (ICP-MS) and differential pulse anodic stripping voltammetry (DPASV). The tuned galvanostatic polarization method for the determination of lead in environmental sample was employed in our study for the very first time. By this application we open a new important direction for electrochemical measurement of ions at low analyte concentrations.