The solid lines are the theoretical
curves according to Eq. (4) and the points (&, & and *) are from
experimental data, which
fit well with the theoretical curves. Since
the
film composition and buffer pH can substantially affect
membrane equilibrium and sensor response characteristics,
optodes made with two different
film compositions were initially
studied as well as two different pH buffered test solutions. Fig. 4
illustrates that when the ionophore amount is doubled (&), almost
all the chromoionophores are protonated in the presence of a high
concentration of nitrite, while only
90% of the chromoionophores