Highly selective and sensitive perchlorate sensors based on some recently synthesized Ni(II)-hexaazacyclotetradecane complexes

Three nickel (II) -hexaazacyclotetradecane complexes were studied to characterize their abilities as perchlorate ion carrier in PVC membrane electrodes. The electrodes based on these complexes exhibit Nernstian responses for ClO(4)(-)over very wide concentration ranges (1.0 x 10(-1) -5.0 x 10(-7) M) with detection limits of 2.0 x 10(-7) -5.0 x 10(-7) M (20-50 ng/mL). The sensors show very good selectivity for ClO(4)(-) ion in comparison with the most common organic and inorganic anions. The responses of the proposed electrodes are independent of pH in the range of 3.5-11.0. The perchlorate selective membranes show fast response time (< 10 s) and can be used for 4 - 12 weeks without any major deviation. The sensors were successfully used to determine the perchlorate ion in water, wastewater and human urine samples.