New Potentiometric Iron(III)-selective Electrode Based on a Tris(Aminophenolate) as a Sensing Molecule

A novel PVC-incorporated membrane electrode selective for iron(III) is described. The sensor is based on the use of novel tris(aminophenolate) sensing molecule Cis,cis-1,3,5-tris{(2- hydroxybenzyl)aminomethyl}cyclohexane (THAC, L). The optimized membrane containing THAC, PVC and o-nitrophenyloctyl ether in the ratio 4:33:63 exhibits the best performance by means of range of concentration (1.0x10-5 to 1.0x10-1M), slope (19.4 mV/decade) and detection limit (7.0x10-6 M). The sensor exhibited a firm response time (< 15 s), extensive working pH range (3.0-6.5), non-aqueous steadiness (up to 20%) and having sufficient long life time (120 days). The potentiometric selectivity coefficients obtained using match potential method (MPM) stipulates outstanding discrimination for Fe3+ ions among the various cations. Additionally, the sensor is found to be conveniently active like a potentiometric indicator electrode in the determination of Fe3+ ions against EDTA.