Abstract
A simple, accurate and precise potentiometric method was developed for the determination of escitalopram oxalate (ESC-OX) in pure form, its pharmaceutical formulations and biological fluids. Three types of sensors: plastic membrane, coated wire and coated graphite rod were constructed from the incorporation of escitalopram (ESC) with phosphomolybdic acid (PMA) or ammonium reineckate (ARK) or phosphotungstic acid (PTA) for the three sensors, respectively. Different parameters affecting the performance of the sensors were studied as pH, soaking time and the selectively of the sensors towards several foreign substances. The sensors exhibit linear response with a Nernstian slope (58.50 +/- 0.42, 57.80 +/- 0.69 and 57.97 +/- 0.52 mV decade(-1) at 25 degrees C) over the concentration ranges 1.0 x 10(-6)-1.0 x 10(-2), 1.0 x 10(-6)-1.0 x 10(-2) and 1.0 x 10(-7)-1.0 x 10(-2) mol L-1, for the three sensors, respectively. The working pH range of the proposed sensors was 3-7. The influence of possible interfering species such as common inorganic cations, sugars and amino acids was studied. The proposed method was validated for linearity, accuracy, intra-day and inter-day precision, robustness and ruggedness according to ICH guidelines. Statistical student's t-test and F-test showed no significant difference between the proposed and reference methods regarding accuracy and precision, respectively.