Preparation of a diclofenac potentiometric sensor and its application to pharmaceutical analysis and to drug recovery from biological fluids

A novel diclofenac ion-selective electrode is prepared, characterized and used in pharmaceutical analysis. The diclofenac complex with hexadecylpyridinium bromide is obtained in situ by soaking the PVC-membranes in a 1 × 10−2 M diclofenac solution. Among four different solvent mediators tested, dibutyl phthalate (DBP) exhibited a proper behavior including Nernstian slope of the calibration curve, fast response time and good reproducibility of the emf values. The electrode exhibits a Nernstian slope of −59 ± 1 mV decade−1 for diclofenac in the concentration range 1.0 × 10−5 to 1.0 × 10−2 M with a limit of detection of 4.0 × 10−6 M. The electrode displays a good selectivity for diclofenac with respect to a number of common inorganic and organic species. It can be used in a pH range of 6.0-9.0. The membrane sensor was successfully applied to the determination of diclofenac in its tablets as well as for its recovery from blood serum and urine samples.