Vk. Gupta et al., PVC-based neutral carrier and organic exchanger membranes as sensors for the determination of Ba2+ and Sr2+, SENS ACTU-B, 55(2-3), 1999, pp. 201-211
Polyvinyl chloride (PVC) based membranes of dibenzo-24-crown-8(I) and 4-ter
t-butylcalix[8]arene (II) with and without plasticizers have been fabricate
d and explored as sensors for Ba2+ and Sr2+, respectively. The membrane inc
orporating the ingredients in the ratio 8:50:6:36 [I:PVC:NaTPB (sodium tetr
aphenylborate): CN (1-chloronaphthalene)] works well over the concentration
range 1.4 x 10(-5)-1.0 x 10(-1) M of Ba2+ with a Nernstian slope of 30 +/-
1 mV per decade of concentration in the pH range 3.5-8.9 while the membran
es of calixarene (11) were tried as Sr2+ selective sensors and it was obser
ved that the membrane incorporating the ingredients in the ratio 9:50:5:36
{II:PVC:NaTPB: TEP [tris-(2-ethylhexyl) phosphoric acid]} showed the best r
esponse with a working concentration range of 2.0 x 10(-5)-1.0 x 10(-1) M a
nd a near-Nernstian slope of 31.3 +/- 1.0 mV per decade of concentration in
the pH range 2.4-4.8. Both sensors exhibit a fast response time of 15 s an
d work well in partially non-aqueous medium having up to 30% (v/v) alcohol
content. The selectivity data showed that the electrodes are sufficiently s
elective over a number of interfering ions including alkaline earth metals.
Anions like Cl-, NO3- also do not interfere in the functioning of the sens
ors. (C) 1999 Elsevier Science S.A. All rights reserved.