A new diclofenac membrane sensor based on its ion associate with crystal violet. Application to diclofenac determination in urine and pharmaceuticals

A novel diclofenac ion-selective electrode has been prepared and used in pharmaceutical analysis. The ion-associate of diclofenac with basic dye (crystal violet) was used as the membrane carrier. Among the four different solvent mediators tested, dibutylphthalate (DBP) exhibited proper behavior including the 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 5.0 × 10^?5-5.0 × 10^?2 M with the limit of detection of 2.5 × 10^?5 M. The electrode displays good sensitivity with the respect to a number of common inorganic and organic species. It can be used in a pH range of 6–11. The membrane sensor was successfully applied to the determination of diclofenac in capsules and for its recovery from urine samples.