Novel potentiometric PVC-membrane and coated graphite sensors for lanthanum(III)

摘要

Preliminary theoretical studies revealed the selective complexation of his (2-mercaptoanil) diacetyl (BMDA) with La3+ over several alkali, alkaline earth and heavy metal ions. Thus, novel PVC-based membrane (PBM) and coated graphite membrane (CGM) sensors for La(III) based on BMDA were prepared. The electrodes display Nernstian behavior over wide concentration ranges (i.e., 1.0 x 10(-5)-1.0 x 10(-1) M for PBM and 1.0 x 10(-6)-1.0 x 10(-1) M for CGM). The potential response of sensors was pH independent in the range of 4.0-8.0. The sensors possess satisfactory reproducibility, fast response time ( < 15 s), and specially excellent discriminating ability for La3+ ions with respect to most of the cations. The membrane sensor was used as an indicator electrode in potentiometric titration of lanthanum ions with EDTA. The coated graphite membrane electrode was applied in determination of fluoride ions in mouth wash preparations.