Highly Selective Sensors for Assay of Donepezil Hydrochloride by Potentiometry: Green Approaches

Donepezil hydrochloride (DPH), an indan and piperidine derivative, is a selective medicament of Alzheimer’s disease. Two highly selective and eco-friendly membrane based sensors have been designed to determine DPH. Sodium tetraphenyl boron (STPB) and sodium phosphotungestate (SPT) have been used as ion-exchangers, for construction of Sensors 1 and 2, respectively, with β-cyclodextrin (β-CD) as ionophore and nitrophenyl octyl ether (NPOE) as a plasticizer. The sensors are highly capable to determine DPH of linear concentration range 1.0 × 10-6 to 8.0 × 10-3 M at the pH ranged between 5 and 8. The regression coefficient values for the resulted calibration lines were 0.9992 and 0.9984 with Sensor 1 (DPH-STPB sensor) and Sensor 2 (DPH-SPT sensor), respectively. The Nernstian slopes of 58.51±0.80 and 57.24±0.67, for Sensor 1 and 2, respectively, reflected the appropriate functioning of sensors in relative to concentration of DPH. The limits of detections (LOD) values were calculated to be 6.3×10-7 and 7.14×10-7 M for Sensor 1 (DPH-STPB sensor) and Sensor 2 (DPH-SPT sensor), respectively. The results from validation of both the sensors reflected high selectivity for measuring potential of DPH solutions. Sensors have been subjected to validity check through accuracy, precision, robustness and ruggedness. Specific functioning of Sensor 1 and 2 permitted to achieve 99.26% as mean recovery of DPH from tablets analyses. The outcome of statistical tests between the results from sensors 1 and 2 with reference method pronounced the extraordinary applicability of the proposed new methods to determine DPH in pharmaceuticals. These methods are greener approaches due to the non-usage of any organic toxic solvent and pre-treatment and extraction steps’ absence.