MicroITIES Detection of Nitrate by Facilitated Ion Transfer

A microITIES array, created by laser photoablation of a 12-microm polyester film, was used to investigate electroassisted anion transfer between two immiscible electrolyte solutions. Besides measuring directly the transfer of nitrate to the organic phase, the enhancement of transfer of the cation (K+) by facilitated anion (counterion) transfer was measured as well. In the presence of a triamide derived from tris(2-aminoethyl)amine (tren), which is known to function as a host for nitrate, the current responses for both nitrate and potassium transfer were monitored. The linear relationships between the current responses and nitrate concentration formed the basis of an anion sensor with a dynamic range from 0.1 to 5 mM. A dual facilitated transfer mechanism is proposed to explain the enhancement phenomenon.