Evaluation and characteristics of a Pb(II) ion-selective electrode based on aquatic humic substances

An ion-selective poly(vinyl chloride) PVC membrane electrode based on humic substances (HS's) isolated from swamp water was developed for the detection of Pb(II) in aqueous solutions. The electrode exhibited a nearly theoretical Nernstian slope of 28.6 mV per decade in the range of Pb(II) concentrations from log(10)(a(Pb(II))) -5.5 to -2.2 with a detection limit of log(10)(a(Pb(II)))=-5.7 in the steady-state mode. The electrode showed good sensitivity, selectivity, and rapid response for Pb(II) in acidic solution (pH=4.50). The interference study of some alkali, alkaline, and heavy metal ions showed that these metal ions did not exhibit interference on the ion-selective electrode (ISE) in its detection of Pb(II) under the conditions employed in this study. The electrode was used to determine Pb(II) in synthetic soil samples by flow injection potentiometric analysis. The investigation into the interaction between HS's and Pb(II) using fluorescence spectroscopy showed that complexation of Pb(II)) by the HS's results in the potential response of this electrode. (C) 2000 Elsevier Science B.V. All rights reserved.