Sequential injection lab-on-valve procedure for the determination of amantadine using potentiometric methods

Amantadine potentiometric detectors were developed, evaluated and incorporated in a SIA-LOV manifold in order to accomplish the control of pharmaceutical formulations and urine. The electrodes incorporate a-cyclodextrin as ionophore, dibutyl phthalate or 2-fluorophenyl 2-nitrophenyl ether as plasticizers and potassium tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate (KTFPB) as cationic additive. The slope increased from 61.2 to 63.8 mV decade(-1) and the practical limit of detection from 2.6 x 10(-6) mol L-1 to 2.5 x 10(-5) mol L-1 when the plasticizer was changed from 2-fluorophenyl 2-nitrophenyl ether to dibutyl phthalate. When incorporated in the flow-manifold the membranes composed by dibutyl phthalate or with 2-fluorophenyl 2-nitrophenyl ether presented slopes and a practical limit of detection of 69.8 mV decade(-1) and 1.5 x 10(-4) mol L-1 or 73.7 mV decade(-1) and 5.4 x 10(-5) mol L-1, respectively. The electrode presented stable responses for over a year, and were highly selective concerning the representative species of the two sample matrices assayed as interferents. Comparison of obtained results with those provided by reference methods and recovery assays, revealed adequate accuracy for control assays.