title: p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix.
abstract: The characteristics, performance, and application of an electrode, namely, Pt|Hg|Hg(2)(PABzt)(2)| graphite, where PABzt stands for p-aminobenzoate ion, are described. This electrode responds to PABzt with sensivity of (58.1+/-1.0) mV per decade over the range 1.0x10(-4) to 1.0x10(-1)moll(-1) at pH 6.5-8.0 and a detection limit of 3.2x10(-5)moll(-1). The electrode shows easy construction, fast response time (within 10-30s), low-cost, and excellent response stability (lifetime greater than 6 months, in continuous use). The proposed sensor displayed good selectivity for p-aminobenzoate in the presence of several substances, especially, concerning carboxylate and inorganic anions. It was used to determine p-aminobenzoate in pharmaceutical formulations by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by an HPLC procedure.
authors.affiliation: Instituto de Quimica-UNESP, P.O. Box 355, CEP 14801-970, Araraquara, SP, Brazil.
authors.forename: A O
authors.initials: AO
authors.lastname: Santini
authors.forename: E S
authors.initials: ES
authors.lastname: Silva
authors.forename: H R
authors.initials: HR
authors.lastname: Pezza
authors.forename: A L M
authors.initials: AL
authors.lastname: Nasser
authors.forename: C B
authors.initials: CB
authors.lastname: Melios
authors.forename: L
authors.initials: L
authors.lastname: Pezza