1998 Volume 47 Issue 3 Pages 179-185
A new preconcentration on-line system for trace copper(II) determination was developed based on the adsorption of copper(II) on the walls of Teflon tubes using flow injection analysis(FIA). Copper(II) was concentrated as hydroxide or colloid on the inner walls of Teflon tubes. The present FIA apparatus had triple channels, and dual injectors were used in a carrier stream. A nitric acid solution (100μl) was loaded in the sample loop of one injector. The sample solution containing copper(II) was loaded in another injector, where copper(II) was adsorbed. The copper(II) adsorped on a Teflon capillary tube (3m in length, i.d. 0.5 mm) was eluted on-line with a nitric acid solution, and was then determined with ascorbic acid and ο-phenylenediamine by fluorometry. The copper(II) was determined over the range of 0.025 to 200 ppb by the present method. The detection limit for copper(II) was 0.008 ppb. The RSD was 2.3% for 1 ppb Cu(II) (n = 7). The treatment of Teflon tubes with a 2 M NaOH solution enhanced the adsorption of copper(II). The optimum conditions of copper(II) determination by the present method were as follows: sample solution, pH 6.0; NaOH concentration, 2 M; adsorption flow rate, 0.4 ml/min ; adsorption time, 10 min. The interference in the determination of copper(II) with diverse ions, i.e. V(V) Cr(VI), Fe (III), Hg(II), Mn(II), Cd(II), La(III), Y(III) and Tl(I) could be decreased by adsorption preconcentration without a masking agent. The results of a trace Cu(II) determination in tap water showed good agreement with the values obtained by graphite-furnace AAS.
