Novel Flow-through Potentiometric System for Dimethyamine Assessment Using New Ion Exchangers Doped-polymeric Membrane Sensors

New simple potentiometric sensing systems are described for the sensitive and selective monitoring of dimethylamine (DMA). These systems are based on using polymeric membranes doped in some ion exchangers such as dimethylamine/phosphomolybdate [(CH3)(2)NH3](2)(2+)[MP](2-) (Sensor I), dimethylamine/tetraphenylborate [(CH3)(2)NH3](+)[TPB](-) (Sensor II) and dimethylamine/phosphotungstate [(CH3)(2)NH3](+)[TP](-) (sensor III). All the sensing systems are incorporated in poly(vinyl chloride) matrix plasticized with o-NPOE. In a Trizma buffer solution of pH 7.1, the sensors exhibit a stable, fast and linear response for 5.0x10(-6)-1.0x10(-2), 2.5x10(-5)-1.0x10(-2), and 5.0x10(-6)-1.0x10(-2) mol L-1 DMA(+) with slopes of 53.2 +/- 0.4, 49.4 +/- 0.6, and 53.8 +/- 0.3 mV decade(-1), and detection limits of 2.0x10(-6) (0.16 mu g mL(-1)), 1.6x10(-5)(1.3 mu g mL(-1)), and 1.4x10(-6) (0.11 mu g mL(-1)) mol L-1 for sensors (I), (II), and (III), respectively. Potentiometric selectivity measurements of these sensors reveal negligible interferences from most common aliphatic and aromatic amines. Satisfactory results are obtained with an average accuracy of 99.5 % and a mean precision of +/- 0.5 %. Validation of the proposed assay methods are examined by measuring the limit of detection, linearity range, accuracy, precision, within-day repeatability, between-days reproducibility and method ruggedness. Good performance characteristics and applicability of these sensors for DMA assessment in different matrices under static and hydrodynamic modes of measurements are demonstrated. The proposed sensors are also prepared in a tubular form and used as DMA detector in a two-channel flow injection setup for continuous monitoring. The frequency rate is 27-53 samples h(-1). The sensors are satisfactory applied for DMA quantification in both biological matrices and environmental samples with recoveries ranging between 95.0 and 104.0 %.