ONLINE ALUMINUM PRECONCENTRATION ON CHELATING RESIN AND ITS FIA SPECTROFLUOROMETRIC DETERMINATION IN FOODS AND DIALYSIS CONCENTRATES

A new, sensitive and rapid spectrofluorimetric flow-injection method, is presented for the determination of trace levels of aluminium based on the formation of a fluorescent complex between aluminium and 5,7-dibromo-8-quinolinol (DBQ), and its extraction into diethylether (lambda(exc) = 400 nm, lambda(em) = 525 nm). Experimental conditions such as pH, reagent concentration, flow-rates, sample volume, extraction coil length, etc., have been optimized for on-line and batch procedures. The detection limits are 1 ppb and 0.3 ppb for batch and on-line systems respectively. The coefficient of variation is 3.0% at the 4 ppb level for the FIA system. To remove interferences and to preconcentrate aluminium, a chelating resin microcolumn which was able to selectively complex Al(III) and was obtained by immobilizing Chromotrope 2B on AG1-X8 ion-exchange resin, was incorporated into the FIA system. The proposed method was successfully applied to determine aluminium in tap water, food samples and dialysis solutions.