Potentiometric Study of Coated Graphite Electrode and Polymeric Membrane Electrode for the Determination of Sm3+Ion

Preliminary studies on the two Schiff bases N2-((3H-indol-3-yl)methylene)-6-phenyl-1,3,5-triazine-2,4-diamine (L1) and N2,N4-bis((3H-indol-3-yl)methylene)-6-phenyl-1,3,5-triazine-2,4-diamine (L2) have shown that they can act as Sm3+ selective electrodes. The performances of a polymeric membrane electrode and a coated graphite electrode based on L2 were compared and the CGE proved to be better, as it shows a low detection limit of 1.8x10-8 mol?L-1, a Nernstian slope of 19.6 +/- 0.4 mV decade-1 of activity with a response time of 11 s in the pH range of 3.09.0. The CGE was used to determine Sm3+ in medicinal plants and soil samples. It was also used to determine fluoride ions in mouthwash samples and in toothpaste.