Novel gadolinium poly(vinyl chloride) membrane sensor based on a new S–N Schiff’s base Original Research Article

In this work, a novel gadolinium membrane sensor based on new S–N Schiff,s base (2-[{3-[(2-sulfanylphenyl)imino)-1-methylbutylidene}amino]phenyl hydrosulfide (SMPH) is presented. The sensor displays a linear dynamic range between 1.0×10−1 and 1.0×10−5 M, with a nice Nernstian slope of 19.8±0.3 mV per decade and a detection limit of 3.0×10−6 M. The best performance was obtained with a membrane composition of 33% poly(vinyl chloride), 61% benzyl acetate, 2% sodium tetraphenyl borate and 5% SMPH. The potentiometric response of the sensor is independent of the pH of the solution in the pH range of 4.0–8.0. The sensor possesses the advantages of short conditioning time, very fast response time, and especially, very good selectivity towards a large number of cations, such as Sm(III), Ce(III), La(III), Cu(II), Pb(II) and Hg(II). The electrode can be used for at least 9 weeks without any considerable divergence in the potentials. It was used as an indicator electrode in potentiometric titration of Gd(III) ions with EDTA, and recovery of Gd(III) from various binary mixtures. The electrode was also applied to the determination of Gd(III) in a urine sample.