Bd. Pendley et E. Lindner, A chronoamperometric method to estimate ionophore loss from ion-selective electrode membranes, ANALYT CHEM, 71(17), 1999, pp. 3673-3676
A novel chronoamperometric method was developed to estimate the concentrati
on of a neutral ionophore in fixed-site, dioctyl sebacate plasticized, poly
(vinyl chloride)based, ion-selective electrode membranes. The membranes con
tained between 0.5 and 16 mmol/kg valinomycin. The chronoamperometric techn
ique was used to estimate the valinomycin concentration in freshly prepared
membranes and after extraction of some of the ionophore from the membranes
using dioctyl sebacate. Replicate measurements indicated a relative standa
rd deviation in the calculated valinomycin concentration of less than 10%,
and these values accurately represented the true concentration of valinomyc
in within 10%, The method permitted an estimate of the valinomycin concentr
ation after valinomycin was leached from a membrane. The results of prelimi
nary experiments using heparinized dog blood suggest that blood protein ads
orption does not interfere qualitatively or quantitatively with the analysi
s.