Synthesis of Poly(Benzyleugenol) and Its Application as an Ionophore for a Potassium Ion-Selective Electrode

Abstract

Poly(benzyl eugenol)(PBE) as novel ionophores for a K+ ion selective electrode was
synthesized by acid catalyzed polymerization of benzyl eugenol. The polymerization
product was characterized by IR and 1H NMR. The electrode membranes based on the
polymer were prepared in the composition of 3 wt% of PBE, (67-n) wt% of 2-
nitrophenyl octyl ether (o-NPOE) as a membrane plasticizer, n wt% of oleic acid as a
lipophilic anionic additive (which n were varied from 0-10) and 30 wt% of PVC as a
membrane matrix. Each membrane electrode was characterized for their performance
as an ion-selective electrode membrane, that was selectivity, Nernst factor, limit of
detection (l.o.d.), response time, and lifetime. Experimental results showed that the
electrode membrane based on PBE with 3 wt% of oleic acid exhibited the best selectivity
for K+ ion relative to other alkali and alkali earth metal ion. The K+-ISE based on PBE
with the membrane composition of 3 wt% PBE, 3 wt% oleic acid, 64 wt% o-NPOE and
30 wt% PVC exhibited potentiometric selectivity toward NH4+, Na+, Mg2+, Ca2+, Ba2+ and
Al3+ of -0.6; -1.3; -3.2; -2.5, -2.2 and -2.5; respectively. This electrode gave a subNernstian response with a slope of 56.3 mV/decade; the response time of c.a. 30 s; the
dynamic range of 10-4 – 10-1 M and limit of detection of 10-4.7 M. The electrode may be
used for continuous measurement at least up to two weeks.