An electrode immobilized in a graphite matrix with ion pair complex for the determination of diclofenac in pharmaceuticals

A simple, precise, rapid and low-cost potentiometric method for diclofenac determination in pharmaceuticals is proposed. A new diclofenac-sensitive electrode was constructed by incorporating the diclofenac ion pair complex with butyl rhodamine B into graphite matrix. The electrode exhibited a linear response over the concentration range of 1 × 10-4 – 5 × 10-2 mol L-1, a detection limit of 3.9×10-5 mol L-1 with a Nernstian slope of 61 ± 2 mV decade-1. The working pH range is 6-11. The electrode is easily constructed, has fast response time (3-11 s) and can be used for the period of six months without any considerable deterioration. The proposed sensor displays good sensitivity for diclofenac in the presence of several substances. It was used to assay diclofenac in pharmaceuticals.