Flow injection potentiometry by a novel coated graphite electrode based on 5-(9-anthracenylmethyl)-5-aza-2,8-dithia[9],(2,9)-1,10-phenanthrolinophane for the selective determination of uranyl ions

Spectrofluorimetric studies on the binding properties of 5-(9-anthracenylmethyl)-5-aza-2,8-dithia[9],(2,9)-1,10-phenanthrolinophane (L) toward different heavy metal ions in methanol solution revealed its selective 2:1 (ligand/metal) complexation with uranyl ion. Consequently, L was used as a suitable ionophore for the preparation of new plasticized PVC membrane-selective electrodes for the determination of uranyl ion by flow injection potentiometry. The electrodes resulted in Nernstian responses for UO2 2+ ion over wide concentration ranges (1.0×10−6 to 1.0×10−1M with a detection limit of 8.3×10−7Mfor polymeric membrane electrode, PME, and 1.0×10−7 to 1.0×10−1Mwith a detection limit of 7.5×10−8Mfor coated graphite electrode, CGE). The potentiometric response is independent of the pH of test solution in the pH range 2.5–4.0. The proposed electrodes possess very good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. The CGE was used in flow injection potentiometry and resulted in well defined peaks for uranyl ions with stable baseline, excellent reproducibility and very high sampling rate of 160 injections h−1. The proposed FIP system was used for the determination of trace uranyl ions in real and synthetic samples.