Abstract :
Novel ionophore, Chiophenecalix[4]resorcinarene (I) has been synthesized and characterized by IR, NMR and C, H, N analysis. Poly(vinyl chloride) (PVC) based membranes of ionophore (I) using dibutylphthalate (DBP), dioctylphthalate (DOP), 1-chloronapthalene (CN), tris(2ethylhexyl) phosphate (TEHP) and bis(2ethylhexyl)sebacate (DOS) as plasticizing solvent mediators were prepared and used as Cro2-2 selective sensors. Of the various sensors prepared, the one with membrane composition 2:66:120 mg (I: PVC: DBP) exhibited the best performance. This sensor works well over a wide concentration range 5.6 * 10^-6-1.0 * 10-1 M (detection limit ~0.30 ppm) with Nernstian compliance (29.0 mV per decade) between pH 6.5-10.0 with a fast response time of ~13 s. The selectivity coefficient values as determined by fixed interference method (FIM) indicate excellent selectivity for Cro2-2 ions over a large number of anions. The sensor exhibits adequate shelf-life ( ~5 months) with good reproducibility (S.D. +- 0.2 mV). The sensor has been used in the potentiometric titration of chromate with Pb(II). Determination of chromium in electroplating waste using the sensor was successfully achieved.
