Comparative Study of Beta Cyclodextrin and Calix-8-Arene as Ionophores in Potentiometric Ion-Selective Electrodes for Sitagliptin Phosphate.

Two novel Sitagliptin (STG) selective electrodes were investigated with di-octyl phthalate as a plasticizer in a polymeric matrix of polyvinyl chloride (PVC). Sensor 1 was fabricated using β-cyclodextrin, while sensor 2 was constructed using calix-8-arene as ionophores. Linear responses of STG within the concentration ranges of 10−7 to 10−2, and 10−8 to 10−2 mol L−1 were obtained using sensors 1 and 2, respectively. Nernstian slopes of 58.57 and 59.88 mV/decade over the pH range of 5-6.5 were observed. The selectivity coefficients of the developed sensors indicated excellent selectivity for STG. The proposed sensors displayed useful analytical characteristics for the determination of STG in bulk powder, different pharmaceutical formulations, and biological fluids (plasma and urine).The two novel electrodes offer the advantage of determination of STG in biological fluids without pretreatment which is convenient for monitoring STG levels in clinical studies.