Potentiometric Responses of Ion-Selective Electrodes Doped with Diureidocalix[4]arene towards Un-dissociated Benzoic Acid

Diureidocalix[4]arene have been applied as new ionophore in liquid membrane electrode (ISE) sensitive towards un-dissociated benzoic acid. The electrode demonstrated response towards benzoic acid with the detection limit 2.0 × 10(-4) M which is sufficient for the determination of benzoic acid added to beverages as preservative in milimolar concentration. The selectivity coefficients measured by the matched potential method (MPM) showed its good selectivity against common anions present in drink samples. All measurements were made in presence of 1.0 × 10(-2) M NaHSO(4) pH 3.0 in order to reduce the influence of OH(-). The applicability of diureidocalix[4]arene incorporated ISE has been checked by recovery test of benzoic acid in the presence of artificial drink matrix and by standard addition method.