A Novel Potentiometric Sensor for Selective Determination of Dodecyl(2-Hydroxyethyl)-Dimethylammonium Bromide Surfactant in Environmental Polluted Samples

A potentiometric method is described for the determination of dodecyl(2-hydroxyethyl)dimethylammonium (DHDA) cationic surfactant using a chemically modified carbon paste sensor based on potassium tetrakis(4-chlorophenyl) borate (KTpClPB) ionophore as an electroactive material. Under optimum experimental variables, the response of electrodes is linear within the concentration range of 2x10(-6) - 1x10(-2) and 1x10(-7) - 1x10(-2) mol L-1 with a Nernstian slopes of 51.19 +/- 1.15 and 59.79 +/- 0.83 mV decade(-1) of dodecyl(2-hydroxyethyl) dimethylammonium (DHDA) cation concentration with detection limit of 2x10(-6) and 1x10(-7) mol L-1 for unmodified CPE (electrode (I)) and KTpClPB-CPE (electrode (IV)), respectively. The electrodes response is independent of pH in the range of 3-7.5 and 2-9, while the response time of the electrodes was similar to 11 and 8s for electrode (I) and electrode (IV), respectively. The electrodes have been successfully used as indicator electrodes for the potentiometric titration of DHDA in the analytical grad solutions, with a potential jump amounts to 197 and 292 mV for electrode (I) and electrode (IV), respectively. The potentiometric selectivity coefficients of the proposed DHDA-selective electrode (IV) towards various interfering ions were determined by applying both matched potential (MPM) and fixed interference (FIM) methods. The frequently used DHDAB of analytical and technical grade as well as different water samples has been successfully titrated and the results obtained agreed with those obtained with standard two phase titration method. The sensitivity of the proposed method is comparable with the official method and ability of field measurements.