Investigations into optical sensing of cupric ions using several immobilized reagents

Optical Cu(II) ion sensors, based on several reagents such as 1-nitroso-2-n apthol (NN), 2,4-dinitrosoresorcinol (DNR), 4-(2-pyridylazo)resorcinol (PAR ), 1-(2-pyridylazo)-2-naphthol (PAN), immobilized on a variety of polymeric materials such as XAD-4, XAD-7, and Dowex have been studied. A kinetic app roach was used to determine the sensor response to Cu(II) concentration, wh ere the reflectance signals measured after a fixed time were utilized. The relative standard deviations (%) attained with these sensors were satisfact ory (RSD -0.97 - 1.15 %). Important parameters such as pH, measurement wave length, and immobilized reagent concentration have been optimized. The pH d ependence and complex formation constant of the Cu (II)-NN/XAD-7 complex ha ve also been investigated along with important sensor characteristics such as, response time (1-4 min), linear range (0.5-20 ppm), detection limit (0. 5-1.0 ppm), and sensor regeneration.