APPLICABILITY OF A SOL-GEL DERIVED CEO2TIO2 THIN-FILM ELECTRODE AS ANAMPEROMETRIC SENSOR IN FLOW-INJECTION

A sol-gel derived CeO2-TiO2 (CTO) thin film, deposited on a glass subs trate with an electrically conductive layer of indium tin oxide (ITO), was investigated with regard to its potential use for amperometric de tection in flow injection (FI), using a thin layer cell set-up, Cyclic voltammetry was employed for basic studies on the electrochemical beh aviour of the CTO film in aqueous LIOH solutions under batch and conti nuous flow conditions, The dependence of the amperometric response of the CTO film on experimental parameters under FI conditions, such as f low rate of the carrier, operating potential and injection volume, was investigated with LiOH and LiCl. The amperometric signal was linearly dependent on the Li+ concentration over the range 4.0 x 10(-4)-4.0 x 10(-3) mol l(-1), For a concentration of 10(-3) mol l(-1) Li+, the RSD of eight consecutive measurements was 5.7% and was comparable to that of conductivity detection (3.7%), Comparison of amperometric with con ductometric detection of Li+, Na+, K+, NH4+ and tetraethylammonium ion s, in the presence of different counter ions, indicated that the resul ts of both detection modes correlate well.