A sequential injection (SI) on-line lab-on-valve separation/preconcentration system incorporating a renewable ion-exchange micro-column interfaced with inductively coupled plasma mass spectrometry (ICP-MS) via a home-made direct injection high efficiency nebulizer (DIHEN) is described. Aimed at eliminating spectroscopic and non-spectroscopic interferences, the renewable micro-column is first loaded by aspirating 15ml of a SP Sephadex C-25 cation-exchanger bead suspension and then exposed to a defined volume of sample solution. Residuals of matrix components are pre-eluted with carrier solution (nitric acid,1: 80v/v), and the measurands are subsequently eluted with a defined volume of nitric acid (1: 16v/v). The leading volume of eluate (ca. 30ml) is collected and introduced into the plasma via the DIHEN. The eluted beads are then discarded and a new column is aspirated for the next operation. Data acquisition is performed in parallel with the ensuing preconcentration process. With 2.0ml sample loading, the enrichment factors are 35.2 (0.05-2.4mg l21) for Ni, and 9.1 (0.04-1.6mg l21) and 28.4 (1.6-3.2mg l21) for Bi. The detection limits (3s) are 15 ng l21 (Ni) and 4 ng l21 (Bi), while the sampling frequency is 12 per hour. The precisions are 2.9% (0.8mg l21 Ni) and 1.7% (0.8mg l21 Bi). The procedure is validated by determination of nickel and bismuth in a certified reference material (CRM 320, River Sediment), and the recoveries are measured by spiking two human urine samples.