Strontium(II)-selective electrode based on a macrocyclic tetraamide.
A new PVC membrane electrode based on 5,7,12,14-dibenzo-2,3,9,10-tetraoxa-1,4,8,11-tetraazacyclotetradecane (I) as an ion carrier, o-nitrophenyloctyl ether (o-NPOE) as solvent mediator and sodium tetraphenylborate (NaTPB) as lipophilic additive was fabricated and investigated as Sr(2+)-selective electrode. The best performance was exhibited by the membrane having composition 8:200:4:120 (I:o-NPOE:NaTPB:PVC). The electrode exhibited a Nernstian response for strontium ion over a wide concentration range 3.98 x 10(-6) to 1.0 x 10(-1)M with a slope of 29.0+/-0.1 mV/decade of concentration and a detection limit of 2.82 x 10(-6)M. It showed a response time of less than 10s and could be used for at least 3 months without any divergence in potential. The proposed electrode showed a good discriminating ability towards strontium(II) ion over a wide variety of other metal ions including alkali, alkaline earth, transition, and heavy metal ions. The electrode can be used in the pH range of 2.5-10.5 and in mixtures containing up to 35% (v/v) non-aqueous content. It was used as an indicator electrode in potentiometric titration of strontium ion against EDTA.
Singh
A K
AK
Department of Chemistry, Indian Institute of Technology, Roorkee, India. akscyfcy@iitr.ernet.in
Saxena
Puja
P
Mehtab
Sameena
S
Gupta
Barkha
B