A novel type of aldehyde-selective electrode was designed based on the
host-guest interaction between p-tert-butylcalix[4]arene ionophore an
d hydrazone generated in situ from heptanal and Girard's reagent P. Th
e poly(vinyl chloride) membrane electrode contains 3.5-8% m/m of a tet
raester derivative of calix[4]arene as the neutral carrier and dioctyl
phthalate as the plasticizer. At pH 5.5, the electrode exhibits a Ner
nstian response in the range 1 x 10(-2)-9 x 10(-7) mol l(-1) heptanal
with a slope of 67.7 mV per concentration decade. The electrode has a
fast response time and a constant Nernstian response after 2 months of
continuous measurement. The viability of using the electrode for the
micro-determination of heptanal was also demonstrated. The minimum det
ectable concentration of aldehyde is 3 x 10(-5) mol l(-1), or, as litt
le as 3.4 mu g of heptanal can be determined accurately by the method.