title: A newly synthesized macrocyclic dithioxamide receptor for phosphate sensing.
abstract: Polyvinyl chloride (PVC) based membranes using macrocyclic dithioxamide receptor (I) derived from isophthaloyl dichloride and dithioxamide have been prepared and explored as HPO(4)(2-)-selective sensors. Effect of various plasticizers viz., bis(2-ethylhexyl) sebacate (DOS), dibutylphosphate (DBP), tri-n-butylphosphate (TBP), O-nitrophenyl octyl ether (NPOE), tris(2-ethylhexyl)phosphate (TEHP) and a cation excluder, tridodecylmethylammonium chloride (TDDMACl) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with the membrane having (I)-PVC-TDDMACl-NPOE in the ratio 2:33:1.5:63.5 (w/w). The sensor works satisfactorily in the concentration range 1.7x10(-6) to 1.0x10(-2)M (detection limit 0.2ppm) with Nernstian compliance (29.6mV/decade of activity) at pH 8.0 with a fast response time of about 8s. The potentiometric selectivity coefficient values as determined by the matched potential method (MPM) and the fixed interference method (FIM) indicate selective response for HPO(4)(2-) in presence of interfering ions. The sensor exhibits adequate shelf life ( approximately 2 months) with good reproducibility (S.D.+/-0.4mV). The sensor was also used successfully in the potentiometric titration of HPO(4)(2-) with Ba(2+).
authors.affiliation: Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Jain
authors.forename: V K
authors.initials: VK
authors.lastname: Gupta
authors.forename: J R
authors.initials: JR
authors.lastname: Raisoni