Amperometric flow injection analysis as a new approach for studying disperse systems

EUSTAQUIO M. ERRO; CARLA E. GIACOMELLI; M. ROSARIO PEREZ; M. ANGELES ULIBARRI; PATRICIA I. ORTIZ; RICARDO ROJAS

ANALYTICA CHIMICA ACTA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2009 vol. 55 p. 475 - 479

0003-2670

a b s t r a c tFast and simple quantitative determination in dispersed systems (layered double hydroxides ? LDHs ?suspensions in aqueous solutions) was performed by a procedure that couplesflowinjection and amperometricdetection (FI-AM). LDH dispersions are injected in a continuous flow (1mLmin−1) of 0.05 mol L−1KNO3 solution and [Cu(H2O)6]2+, used as a probe, is detected at a glassy carbon electrode housed in aflat electrochemical cell. The current intensity, recorded at the selected working potential (−0.25V vsAg/AgCl/NaCl (3 mol L−1)), presents a linear relationship with [Cu(H2O)6]2+ concentration and the procedureoffers high sensitivity (slope = 0.036A/(mol L−1)), a low detection limit (=0.7mol L−1) and awide quantification range (4?200mol L−1).The method was applied to [Cu(H2O)6]2+ determination in two particular LDH-aqueous solutiondispersed systems: (1) [Cu(H2O)6]2+ scavenging by etilendiammintetraacetic acid (EDTA) modified Zn-Al-LDHs, and (2) [Cu(H2O)6]2+ release from a copper doped Mg-Al-LDHs. The results obtained are comparableto those reported in previous works using different quantification techniques. FI-AM determination isapplied without sample pretreatment (solid?supernatant separation) providing a high sampling rate(above 120 samples h−1) that allows a better comprehension of the processes, particularly at the initialstages.