A PVC-based sensor for La3+ ions based on N-[hexahydrocyclopentapyrol-2((1H)yl)amino]carbonyl]-4-methyl benzene sulfonamide (gliclazide) as a novel carrier was prepared. The electrode exhibits a Nernstian response for La3+ over a wide concentration range (1.0 x 10(-1)-1.0 x 10(-6) M) with a slope of 20.1 mV per decade. The limit of detection is 8.0 x 10(-7) M. The sensor has a very short response time ( < 15 s) and a useful working pH range of 4.0-8.0. The proposed membrane sensor shows excellent discriminating ability towards La3+ ions with regard to several alkali, alkaline earth, transition and heavy metal ions. The electrode was successfully applied for determination of La3+ in binary mixtures. (C) 2002 Elsevier Science B.V. All rights reserved.