p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix |
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Authors: | Santini A O Silva E S Pezza H R Nasser A L M Melios C B Pezza L |
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Affiliation: | Instituto de Quimica-UNESP, P.O. Box 355, CEP 14801-970, Araraquara, SP, Brazil. |
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Abstract: | 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 1.0×10−1 mol l−1 at pH 6.5-8.0 and a detection limit of 3.2×10−5 mol l−1. The electrode shows easy construction, fast response time (within 10-30 s), 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. |
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Keywords: | p-Aminobenzoate-sensitive electrode Potentiometry Pharmaceutical formulations |
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