p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix

• Published in: Talanta (Oxford) 2004-07, Vol.63 (4), p.833-838
• Main Authors: Santini, A.O, Silva, E.S, Pezza, H.R, Nasser, A.L.M, Melios, C.B, Pezza, L
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Electrochemical methods; Exact sciences and technology; Other chromatographic methods; p-Aminobenzoate-sensitive electrode; Pharmaceutical formulations; Potentiometry
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2003.12.039

The characteristics, performance, and application of an electrode, namely, Pt|Hg|Hg2(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 1.0×10−4 to 1.0×10−1moll−1 at pH 6.5–8.0 and a detection limit of 3.2×10−5moll−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.