Simultaneous determination of certain selected trace elements with an on-line preconcentrating flow injection ICP-OES system

The detection limits of an ICP instrument were improved by on-line preconce ntrating samples on a miniature ion exchange column incorporated into the c onduits of a flow injection (FI) system. Several operating parameters for b oth the ICP and the ion exchange column were optimised to maximise the adva ntages of the preconcentrating system. These include the pH and loading rat e of the sample, the length and diameter of the column and the eluent conce ntration. The preconcentrating FIA-ICP system gave simultaneous multi-eleme nt detection limits, which were between five and 30 times better than for c onventional continuously aspirating systems for the elements barium, calciu m, chromium, copper, manganese, iron and lead. Precision was better than 3. 5% RSD at the 50 mu g l(-1) level for Ba, Ca, Cr, Cu, Fe and Mn, and the 25 0 mu g l(-1) level for Pb. Analysis of spiked rain water in the mu g l(-1) level gave nearly 100% recovery. The sampling rate was six samples per hour .