A new potentiometric ibuprofenate ion sensor immobilized in a graphite matrix for determination of ibuprofen in tablets

The characteristics, performance, and application of an electrode, namely, Pt|Hg|Hg2(IBP)2|Graphite, where IBP stands for ibuprofenate ion, are described. This electrode responds to IBP with sensitivity of (58.6 ± 0.9) mV decade− 1 over the range 5.0 × 10− 5–1.0 × 10− 1 mol L− 1 at pH 6.0–9.0 and a detection limit of 3.8 × 10− 5 mol L− 1. The electrode is easily constructed at a relatively low cost with fast response time (within 15–30 s) and can be used for a period of 5 months without any considerable divergence in potentials. The proposed sensor displayed good selectivity for ibuprofen in the presence of several substances, especially concerning carboxylate and inorganic anions. It was used for the direct assay of ibuprofen in commercial tablets by means of the standard additions method. The analytical results obtained by using this electrode are in good agreement with those given by the United States Pharmacopeia procedure.